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Image Alchemy
Version 1.7
Handmade Software, Inc.
Notice Handmade Software, Inc. makes no warranty of any
kind either expressed or implied. In particular
we make no warranty as to merchantability or
fitness for a particular purpose.
In no event shall Handmade Software, Inc. be
liable for any errors contained herein or for
incidental or consequential damages in connection
with the furnishing, performance, or use of the
Image Alchemy product or documentation.
This document contains proprietary information
which is protected by copyright. No part of this
document may be photocopied, reproduced, or
translated without the prior written consent of
Handmade Software, Inc.
The information in this document is subject to
change without notice.
Copyright (c) 1990-1993 Handmade Software, Inc.
All Rights Reserved
ii
Printing This manual was created using Microsoft Word 5.1a
history on a Macintosh II computer.
First Printing
Handmade Software, Inc.
15951 Los Gatos Blvd., Suite 17
Los Gatos, CA 95032
+1 800 358 3588
+1 408 358 1292
+1 408 358 2694 fax
+1 408 356 3297 BBS
Internet: [email protected]
CompuServe: 71330, 3136
iii
Author credits
Image Alchemy Marcos H. Woehrmann
was written by Allan N. Hessenflow
David Kettmann
Paul H. Yoshimune
Other credits
Marc Schneider Who provided assistance with the Sun
implementation of Image Alchemy including Beta
testing and answering questions about the internal
format of Sun Raster files.
Jack, Norm, Who proofread the manual (any remaining misteaks
Erwin, and Dave are because we made changes after they read it for
the final time).
Everyone Else Who gave us advice and assistance and especially
to those people who sent us sample image files.
iv
Trademarks Image Alchemy is a trademark of Handmade Software,
Inc.
All other products or services mentioned in this
manual, including: IBM PC, IBM PC AT, 80286,
80386, 80486, VGA, 8514/A, Paradise, Everex,
Trident, Video 7, Tseng Labs, Western Digital, MS-
DOS, PC-DOS, SPARC, Sun, SPARCstation,
SPARCserver, SunOS, Targa, PostScript, EPS,
Encapsulated PostScript, GIF, ILBM, IFF,
Macintosh, Silicon Graphics, SGI, PCX, TIFF,
Windows, Windows BitMaP, EGA, PCL, HP, AI, PS/2,
HAM, PC Paintbrush, MacBinary, PHIPS, NeXT, C-
Cube, Storm Technology, Radius, ColorSqueeze,
VFCtool, Amiga, CompuServe, LaserJet, Melior, and
Gill Sans are trademarks, registered trademarks,
service marks, or registered service marks of
their respective companies or organizations.
Even though they are never mentioned in this
document, you should know that Yellow Pages is a
registered trademark in the United Kingdom of
British Telecommunications plc., and may also be a
trademark of various telephone companies around
the world.
v
Contents
-------------------------------------------------------------------
Chapter 0
Introduction..................................1
About This Manual.............................2
Pathnames.....................................3
Wildcard Expansion............................3
Chapter 1 Installation
Introduction..................................4
MS-DOS
Required Equipment..........................5
Optional Equipment..........................6
Packing List................................7
Installation Instructions...................8
386 for MS-DOS
Required Equipment.........................11
Packing List...............................12
Installation Instructions..................12
Unix
Packing List...............................14
Installation Instructions..................14
Chapter 2 Introduction
Basic Instructions...........................16
Filename Limitations.........................17
Output Path Name.............................18
Option Files.................................29
Multiple Runs of Alchemy.....................21
Chapter 3 Graphical User Interface (MS-DOS Only)
Introduction.................................23
Menus
File.......................................24
Resize.....................................27
Contents 1
Palette....................................27
Colors.....................................28
Dither.....................................28
Chapter 4 Output Options
Introduction.................................30
MacBinary....................................32
Other Information............................32
Image File Formats
ADEX.......................................34
Alpha Microsystems BMP.....................35
Autologic..................................36
AVHRR......................................37
Binary Information File....................39
Calcomp CCRF...............................41
CALS.......................................42
Cubicomp PictureMaker......................43
Dr. Halo CUT...............................45
Encapsulated PostScript....................46
ER Mapper Raster...........................47
Erdas LAN/GIS..............................49
First Publisher ART........................50
Freedom of Press...........................51
GEM VDI Image File.........................52
GIF........................................54
GOES.......................................56
Hitachi Raster Format......................58
HP Printer Command Language................59
HP Raster Transfer Language................63
HP-48sx Graphic Object GROB................66
HSI JPEG...................................67
HSI Palette................................68
HSI Raw....................................69
IBM Picture Maker..........................70
IFF/ILBM...................................71
Img Software Set...........................72
JPEG/JFIF..................................73
Jovian VI..................................76
Lumena CEL.................................77
Macintosh PICT/PICT2.......................78
MacPaint...................................79
MTV Ray Tracer.............................80
Multi-Image Palette........................81
OS/2 Bitmap................................82
PCPAINT/Pictor Page Format.................83
PCX........................................85
PDS........................................88
Portable BitMap............................89
Puzzle.....................................91
Q0.........................................92
2 Contents
QDV........................................93
QRT........................................94
RIX........................................95
Scodl......................................96
Silicon Graphics Image.....................98
SPOT Image.................................99
Stork.....................................101
Sun Icon..................................102
Sun Raster................................103
Tagged Interchange File Format (TIFF).....105
Targa.....................................107
Utah Raster Toolkit.......................108
Vivid.....................................109
Windows Bitmap............................110
WordPerfect Graphic File..................113
XBM.......................................114
XPM.......................................115
XWD.......................................117
Chapter 5 General Options
Introduction................................118
Conserve Memory.............................119
Display Image Stats.........................120
Do Not Alter Output Filename................121
Help........................................122
Overwrite...................................123
Program Information.........................124
Quiet.......................................125
Warnings....................................126
Wildcard....................................127
Chapter 6 Colour and Palette Options
Introduction................................129
Black and White.............................130
Colours.....................................131
Dither......................................133
EGA Palette.................................135
False Colour................................136
Gamma Correction............................137
Match Palette...............................139
Negate......................................140
Palette.....................................141
Palette Selection...........................142
Spiff.......................................144
True Colour (15 bits).......................146
True Colour (16 bits).......................147
True Colour (24 bits).......................148
True Colour (32 bits).......................149
Undercolour Removal.........................150
Uniform Palette.............................151
Contents 3
Chapter 7 Scaling Options
Introduction................................152
Flip Image..................................153
Preserve Aspect Ratio.......................154
Scale Image Horizontally....................155
Scale Image Vertically......................157
Specify Image Aspect Ratio..................158
Specify Image Resolution....................160
Chapter 8 Viewing Options (MS-DOS Only)
Display Hardware............................162
Offset View.................................165
View Image..................................166
View Image in True Colour Mode..............167
View Scaled Image...........................168
View Scaled Image in True Colour Mode.......169
Chapter 9 Tutorial and Examples
Introduction................................170
Appendix A Answers to Frequently Asked Questions
..........................................173
Appendix B Colour and Dithering
..........................................183
Appendix C JPEG Description
..........................................187
Appendix D Customer Support
..........................................190
Appendix E Binary Information Files (BIF)
..........................................192
Appendix F HSI Raw Files
..........................................195
Appendix G Undercolour Removal Files
..........................................199
4 Contents
Appendix H HSI PAL Files
..........................................202
Appendix I Acknowledgments
..........................................203
Appendix J Other Useful Software
..........................................204
Glossary
..........................................207
References
..........................................209
Contents 5
0
Introduction to Image Alchemy
-------------------------------------------------------------------
What is Image Image Alchemy is a software utility that
Alchemy? manipulates computer image files.
Primarily, Image Alchemy converts between various
graphics file formats. Image Alchemy can
translate between a large variety of file formats
including industry standards such as GIF and TIFF
as well as vendor specific file formats such as
Sun Raster and Scodl. Currently Alchemy supports
over 60 different formats, and new formats are
always being added; in fact, our goal is to have
Image Alchemy be able to read and write every
graphics file in the world.
Image Alchemy can also make changes in an image.
For example, Image Alchemy can re-size an image,
change the number of colours in an image, change
an image from colour to black and white, and
change the colour space an image uses.
Finally, Image Alchemy performs JPEG compression.
This is a standard for image compression that can
achieve much higher compression ratios than
conventional compression techniques. It achieves
this high compression ratio by not entirely
preserving the original image (this is referred to
as "lossy" compression). For further information
see Appendix C, "What is JPEG Compression".
Image Alchemy 1
About this This manual is divided into 10 chapters, 11
manual appendices, a glossary, references, and an index.
Chapter 0 Introduction and Conventions
Chapter 1 Installation Instructions
Chapter 2 Introduction to Alchemy
Chapter 3 Graphical User Interface
Chapter 4 Output Options
Chapter 5 General Options
Chapter 6 Colour and Palette Options
Chapter 7 Scaling Options
Chapter 8 Viewing Options
Chapter 9 Tutorial and Examples
Appendix A Answers to Frequently Asked Questions
Appendix B Colour and Dithering
Appendix C JPEG Description
Appendix D Customer Support
Appendix E Binary Information Files (BIF)
Appendix F HSI Raw Files
Appendix G Undercolour Removal Files
Appendix H PAL Files
Appendix I Acknowledgments
Appendix J Other Useful Software
Appendix K Configuring DOS/4GW
Glossary
References
Index
2 Image Alchemy
Pathnames Because the MS-DOS and UNIX operating systems use
different conventions for path names, users of
UNIX will have to substitute forward slashes, "/",
for the back slashes, "\", found in the examples
in this manual.
Unintentional UNIX users should also be aware that the UNIX
wildcard shell they are using may be performing wildcard
expansion expansion on certain characters (generally "*" and
"?"). Since these are options which Alchemy uses,
they need to be escaped to prevent the wildcard
substitution. This is done by using a back slash,
"\", before the character (so -? becomes -\?).
Image Alchemy 3
1
Installing Image Alchemy
-------------------------------------------------------------------
Overview Installation of Image Alchemy is simple; it
involves copying the Alchemy program off of the
floppy disk or tape onto your hard drive or
network.
You need to be familiar with the copy command if
doing a DOS installation and the tar command if
doing a UNIX installation. If you are not
familiar with these commands you may wish to read
the manuals which came with your computer or ask
someone to assist you.
The installation instructions are divided into
different sections for Image Alchemy for MS-DOS,
Image Alchemy/386, and Image Alchemy for UNIX.
Please refer to the section which corresponds to
your hardware.
4 Image Alchemy
Image Alchemy for MS-DOS
-------------------------------------------------------------------
Required At a minimum you must have the following hardware
equipment and software to run Image Alchemy.
Computer An MS-DOS computer equipped with an 80286, 80386,
or 80486.
Many of the conversions that Alchemy does are cpu
intensive, so a faster computer is definitely an
advantage.
Memory At least 400k of free memory.
Some conversions and some images require even more
memory (Alchemy will attempt to use all available
system memory, so if you get out-of-memory errors
or warnings try removing as many resident programs
as you can (also, installing MS-DOS 5.0, MS-DOS
6.0, or a 3rd party memory manager such as 386MAX
or QEMM will free up more memory)).
Alchemy makes use of extended, expanded, and xms
memory while performing conversions. This can
greatly speed up the conversion process. In
general you will need as much memory as the size
of the image, in pixels, being converted. For
example, a 640x480 true colour image will use 900k
of memory).
Hard drive A hard drive with at least as much free space as
four times the size of the image being converted
(i.e. a 640x480 image will require approximately
1.2 megabytes of free space).
Display A supported VGA, 8514/A, or XGA board, if you wish
to view images.
Image Alchemy 5
Supported SVGA boards include those with a VESA
driver or with the Paradise, Everex, Trident,
Video 7, ATI, Ahead, NCR, or Tseng Labs chipsets.
Supported 8514/A boards include IBM and those with
the Western Digital chipset.
Operating MS-DOS or PC-DOS 3.x or greater (because of the
system additional free memory available use of MS-DOS 5.0
or MS-DOS 6.0 is highly recommended).
Optional The following hardware and software is optional to
equipment run Image Alchemy.
VESA VGA board To get full use out of viewing images on a SVGA
board a VESA driver is needed. Without a VESA
driver Alchemy is limited to displaying images in
320x200x256, 360x480x256, and 640x400x256 modes
(and 640x480x32768 if you SVGA board is capable of
15 bit operation); with a VESA driver the
resolution is limited only by your SVGA board and
monitor. Resolutions up to 1280x1024x256 and
1280x1024x16 million are possible.
The VESA driver is supplied by the manufacturer of
your SVGA board. It may already be included in
the BIOS on your SVGA board, or it may have been
shipped on a floppy disk with your SVGA board.
Consult the documentation that came with the SVGA
board. If there is no mention of a VESA driver in
the documentation contact your dealer or the
manufacturer of your SVGA board; VESA drivers are
currently available for VGA boards using chipsets
from Cirrus Logic, ATI Technologies, Chips and
Technologies, Everex Systems, Genoa Systems,
Paradise Logic, Sigma Designs, STB Systems,
Tecmar, Headland Technology (Video 7), Orchid
Technology, Appian Technology, Trident
Microsystems, and Oak Technology.
6 Image Alchemy
Refer to your SVGA documentation on how to install
the VESA driver.
Math A math coprocessor will not affect the speed of
coprocessor most operations; the only operations that use much
floating point math are scaling types c and d.
Packing list The enclosed diskette contains the following
files:
INSTALL.EXE The Image Alchemy installation
program.
ALCHEMY.EXE The Alchemy software.
GUI.EXE The Alchemy menu interface.
READ.ME A text document describing any last
minute revisions.
SAMPLES A directory containing sample data
files and images. See the READ.ME
file in this directory for further
information.
Image Alchemy 7
Installation 1. Insert the appropriate floppy disk in your disk
instructions drive.
2. Change to the drive by typing either a: or b:.
3. Type install. This will install Image Alchemy
in the c:\alchemy directory.
If you would like to install on a different
drive or a specific directory, you can do this
by typing install followed by the location
where you want Image Alchemy installed.
For example: install d:\util\alchemy will
install the software in the d:\util\alchemy
directory.
5. You have now successfully installed Image
Alchemy.
6. The file read.me contains information which has
changed since the manual was printed. To
display the read.me file type type read.me.
Environment
variable usage
Temporary disk Alchemy uses the environment variable TMP to
files determine where to open its temporary files. If
you have a big enough ram drive you will want to
specify it using the TMP variable. Be aware that
Alchemy needs up to 4 times as much space on that
drive as the size of the image (a 640 by 480 image
requires up to 1.2 Megabytes). An example of
setting the TMP variable to drive e: would be "set
TMP=e:".
8 Image Alchemy
Use of extended If there is enough extended or expanded memory
and expanded available, Alchemy will use it instead of the
memory temporary file it would otherwise use during some
conversions. To use extended memory you must have
an XMS driver installed in the config.sys file
(such as HIMEM.SYS or 386MAX). To use expanded
memory you must have a LIM 3.2 or LIM 4.0 expanded
memory driver installed (such as EMM386, QEMM, or
386MAX).
Alchemy's use of extended/expanded memory can be
disabled. To disable the use of extended and
expanded memory, set an environment variable
called 'alchemy' to 'x' (type "set alchemy=x" at
the DOS prompt).
Note that the availability of extended or expanded
memory will not allow you to convert larger
images, it will just increase the speed of
conversions. If you need to convert very large
images we also have a 386 Enhanced version of
Image Alchemy, which will allow 80386 and 80486
users to make use of the linear addressing space
of those processors along with virtual memory to
convert images of up to 32000 x 32000 (assuming
you have enough disk space). Please contact us if
you are running out of memory and are interested
in upgrading to Image Alchemy/386.
Checking for Alchemy will normally check to determine if there
8514/A boards is an 8514/A board installed in the computer when
viewing images. However, this can cause problems
with some network boards, as they use the same I/O
addresses that 8514/A boards use. To disable
8514/A checking, set the environment variable
called 'alchemy' to '8' (type "set alchemy=8" at
the DOS prompt).
Note that this can be combined with other options;
for example, to disable both 8514/A checking and
extended/expanded memory usage, use
"set alchemy=8x".
Image Alchemy 9
Limiting Alchemy will automatically choose the lowest
maximum display resolution which will fit the entire image when
resolution viewing images without specifying a display
resolution with a VESA compatible VGA board.
However, depending on the monitor and VGA board
combination you have, this can be bad since the
monitor may not support the particular resolution
the SVGA board is trying to switch to. To avoid
this problem, the environment variable 'alchemy'
may now be set to indicate the maximum display
resolution which Alchemy should use. Set the
alchemy variable to the highest horizontal
resolution which your monitor is capable of.
Valid values are 1280, 1024, 800, and 640. For
example, type "set alchemy=800" at the DOS prompt
if your monitor only supports 640x480 and 800x600
mode.
Note that this can be combined with other options;
for example, to disable 8514/A checking, disable
extended/expanded memory usage, and limit the
viewing resolution to 640x480 use
"set alchemy=8x640". You can also place this line
in your autoexec.bat file.
10 Image Alchemy
Image Alchemy/386 for MS-DOS
-------------------------------------------------------------------
Required At a minimum you must have the following hardware
equipment and software to run Image Alchemy/386.
Computer An MS-DOS computer equipped with an 80386, 80486,
or other 32bit Intel processor.
Many of the conversions that Alchemy does are cpu
intensive, so a faster computer is definitely an
advantage.
Memory At least 2MB of free memory.
Hard drive A hard drive with at least as much free space as
four times the size of the image being converted
(i.e. a 640x480 image will require approximately
1.2 megabytes of free space).
Viewing Images Alchemy/386 does not support viewing at this time.
Operating MS-DOS or PC-DOS 3.x or greater (because of the
system additional free memory available, use of MS-DOS
5.0 or MS-DOS 6.0 is highly recommended).
Math A math coprocessor will not affect the speed of
coprocessor most operations; the only operations that use much
floating point math are scaling types c and d.
Image Alchemy 11
Packing list The enclosed diskettes contain the following
files:
INSTALL.EXE The Image Alchemy installation
program.
ALCH386.EXE The 32bit version of Alchemy.
DOS4GW.EXE The 32bit DOS extender used by
Alchemy.
ALCHEMY.EXE The real-mode Alchemy software.
READ.ME A text document describing any last
minute revisions.
SAMPLES A directory containing sample data
files and images. See the READ.ME
file in this directory for further
information.
Installation 1. Insert the appropriate floppy disk in your disk
instructions drive.
2. Change to the drive by typing either a: or b:.
3. Type install. This will install Image Alchemy
in the c:\alchemy directory.
If you would like to install on a different
drive or a specific directory, you can do this
by typing install followed by the location
where you want Image Alchemy installed.
For example: install d:\util\alchemy will
install the software in the d:\util\alchemy
directory.
4. You have now successfully installed Image
Alchemy.
5. The file read.me contains information which has
changed since the manual was printed. To
display the read.me file type type read.me.
Environment
variable usage
12 Image Alchemy
Temporary disk Alchemy uses the environment variable TMP to
files determine where to open its temporary files. If
you have a big enough RAM drive you will want to
specify it using the TMP variable. Be aware that
Alchemy needs up to 4 times as much space on that
drive as the size of the image (a 640x480 image
requires up to 1.2 megabytes). An example of
setting the TMP variable to drive e: would be "set
TMP=e:".
DOS/4GW and Please refer to Appendix K for information about
Virtual Memory configuring DOS/4GW and taking advantage of
virtual memory.
Image Alchemy 13
UNIX Installation
-------------------------------------------------------------------
Packing list The enclosed diskette or tape is in tar format and
contains the following files:
alchemy The Alchemy program.
read.me A text document describing any last
minute revisions.
samples A directory containing sample data
files and images. See the read.me
file in this directory for further
information.
Installation Use tar to copy the files from the distribution
instructions disk or tape to the current directory.
To install the software from diskette use:
tar xvf /dev/fd0
For tape installation replace /dev/fd0 with the
name of the tape device. The name of the tape
device varies between different models and
configurations of systems; ask your system
administrator if you don't know the name of your
tape device.
Note to Alchemy uses the environment variable TMPDIR to
advanced users determine where to put its temporary files. This
is usually set to /usr/tmp or /tmp, but if you are
converting very large images there may not be
enough space available in the partition those
directories are on. In that case you may want to
set the environment variable TMPDIR to a different
partition. For example, to set the temporary file
directory to the directory /home/images use
"setenv TMPDIR /home/images". Contact your system
administrator if you have problems with Alchemy
running out of disk space while converting images.
14 Image Alchemy
Image Alchemy 15
2
Introduction
-------------------------------------------------------------------
Basic Image Alchemy is a command-line driven program
instructions with an optional menu system. Historically, Image
Alchemy has been exclusively command-line driven,
and a lot of information in this manual is
necessary for users who prefer the command-line
interface.
For those users who prefer the menu interface, we
have tried to indicate which sections are relevant
to you and which you may safely skip.
Chapter 3 is devoted entirely to the menu
interface (also called a Graphical User Interface,
or GUI), and explains how to use the interface as
well as how Image Alchemy manages both interfaces.
Options Options are the commands that you give Alchemy so
that it knows what you want it to do. So that
Alchemy can distinguish between options and file
names on the command line, options are preceded by
a dash ("-").
The only option that is required is the output
file format (or the viewing option, for MS-DOS
users). Image Alchemy will make reasonable
decisions for all of the other options.
Some options take parameters. The parameters may
immediately follow the option or be separated by a
space. For example, either -c128 or -c 128 is
acceptable.
Information on selecting options from the main
menu is covered in Chapter 3.
The options themselves are documented in Chapters
4 through 8.
16 Image Alchemy
Note that options can appear anywhere in the
command line and generally they can be in any
order (certain options take parameters; in those
cases the parameters must follow the option). The
case of the options is significant.
InputFileName The inputFileName is any valid file name. This is
the name of an existing image file that you are
converting from or viewing. The inputFileName is
required. It may include an optional drive and/or
path.
OutputFileName The outputFileName is the name of the file you are
converting the image to. The outputFileName is
optional; if it is not specified Image Alchemy
generates one by substituting an appropriate
extension to the input file name. If you specify
an outputFileName and it does not include an
extension one will be added. The outputFileName
may include an optional drive and/or path. If you
do not supply a path the current directory will be
used as the destination directory.
OutputPathName The outputPathName is the location where you want
to put the output that Alchemy will create. The
outputPathName is optional; if it is not
specified Alchemy places the output in the current
directory or in the directory specified as part of
the outputFileName.
Limitations on Since on the command line Alchemy lets you
filenames optionally enter a space between an option and its
parameter it is possible to confuse Alchemy if one
of the filenames starts with a number. In
particular, if you use an option which has an
optional parameter, you choose not to use the
parameter, and you follow that option immediately
with a filename which starts with a number,
Alchemy doesn't realize that the filename is not
the parameter. While it sounds unlikely that this
would ever be a problem it actually happens quite
often.
Image Alchemy 17
For example, if you wanted to convert the file
12.gif to a Targa file with the name output.tga
you would have to be careful of the order in which
you specified things.
If you say
alchemy -a 12.gif output.tga
Alchemy would misinterpret that as
alchemy -a12 .gif output.tga
and would generate an error.
The easiest way around this problem is to always
put the filenames first
alchemy 12.gif output.tga -a
or don't use filenames which begin with a number.
Output path The output path name is the location where Alchemy
will place its output.
The outputPathName can be specified on the command
line as part of the outputFileName if you are
specifying an outputFileName.
For example
alchemy sample.jpg -g test.gif \images
is the same as
alchemy sample.jpg -g \images\test.gif
However,
alchemy sample.jpg -g
is not the same as
alchemy sample.jpg -g \images
18 Image Alchemy
When using the wildcard option, Alchemy allows
wildcards and multiple file names. In this case
the use of an outputFileName is not allowed, but
the use of the outputPathName is. See the
wildcard option for more information.
Using option Alchemy can read command line parameters from
files files. Doing this is equivalent to typing the
options on the command line. Lists of options are
useful when you have commonly used commands or
when you have long commands which would be hard to
remember or exceed the command line limits of your
operating system.
To use an option file you will have to create a
text file using a text editor. This file can have
any name or extension you wish. To pass this file
to Alchemy use the @ operator, followed
immediately by the name of the text file.
For example, if you frequently need to scale
images to be no larger than 640x480, using 'b'
quality scaling, and preserving aspect ratio, you
can make a text file which looks like this (called
SCALE, for purposes of this example):
-Xb640 -Yb480 -+
You would then use this text file with Alchemy by
passing its name along with any other options
(including the output file type option). For
example:
alchemy @scale test.gif -g new.gif
would convert the GIF file test.gif to a GIF file
called new.gif, thus performing the desired
scaling operation.
It is also possible to place filenames and other
option lists in options lists. For example, if
you want to convert all of the .gif, .tif, and
.tga files to JPEG files you can create a text
file which looks like this (called FILES):
*.gif
*.tif
*.tga
And then use this command line to convert those
files to JPEG files:
Image Alchemy 19
alchemy @files -j
If you wanted to scale the images at the same time
you would add that option file to the command line
(using the SCALE text file created earlier):
alchemy @files @scale -j
20 Image Alchemy
Using multiple In general, Image Alchemy will perform equally
runs of Alchemy well regardless of how many steps it takes to
accomplish a command. However, if you use
multiple steps, be careful of their order.
Sometimes you may know what you want to accomplish
but not how to specify the correct combination of
options. For example, you may wish to re-size a
true colour Targa file that you have scanned and
convert it to a 16 colour GIF file. Let's say
that the input file name is file.tga and you want
to generate a file with the name file.gif. In this
case you could type:
alchemy file.tga -Xb640 -Yb480 -c16 -g
However, there would be no penalty in quality (and
little in speed) if you did things in two steps:
alchemy file.tga -Xb640 -Yb480 -r temp.raw
alchemy temp.raw -c16 -g file.gif
In this case you are telling Alchemy to use a
temporary raw file called temp.raw. It turns out
that Alchemy would have automatically used a
temporary raw file in the first case. So, except
for having to delete the file temp.raw, both uses
are identical.
The order of steps is important in many cases.
For example, reversing the order of the two
operations in the previous example:
alchemy file.tga -c16 -g temp.raw
alchemy temp.raw -Xb640 -Yb480 -g file
would give different results. This is because the
scaling operation has to temporarily convert the
image to true colour, but the GIF file you are
generating has to be paletted, so the second
operation would re-dither the image.
Sometimes you will have to perform operations
using multiple steps because there are some
combinations of options that Alchemy explicitly
does not allow. These combinations of options are
not allowed because the results would not be what
you expect.
Image Alchemy 21
For example, using the spiff option, -S, in
combination with the false colour option, -F,
would spiff the image first and then false colour
it, which would give the same results as just
using the false colour option. Since that isn't
something that you would ever want to do, Alchemy
will complain if you specify both of those options
at the same time.
In this case you could false colour the image
first, generating a temporary image, and then
spiff that image.
22 Image Alchemy
3
The Graphical User Interface (Menus)
-------------------------------------------------------------------
Introduction Image Alchemy v1.7 is the first release to
incorporate a Graphical User Interface (GUI),
commonly referred to as a menu system. The GUI can
make using Alchemy much easier for casual or
infrequent users, since the various command-line
arguments do not need to be memorized or even
known.
The GUI is actually a separate program which gets
information about the conversion from the user,
builds a command line for Alchemy, and then calls
the actual Alchemy software. In this way, users
who are familiar with the command-line structure
of Alchemy will not be hampered by the menu system
-- the software can be used exactly as with
previous versions. The GUI will also let you view
the command line parameters it uses, so that
interested users can learn more about Alchemy
itself and the switches it requires to perform
various conversions.
Starting the After installing Image Alchemy (described in
GUI Chapter 1), the Alchemy executable as well as the
GUI should be on your working drive. The GUI will
be able to find the Alchemy executable as long as
it is in either the current directory or the DOS
search path.
Once your path has been set, simply typing 'gui'
will start Alchemy's graphical user interface.
The Main Screen Upon starting the GUI, the screen will be mostly
blank, except for a menu bar across the top of the
screen, and two small windows at the bottom
informing you of the currently selected input file
and the output file type.
To access the pull-down menu system, type Alt-?,
where ? is the first character of the option. For
example, typing Alt-F will bring down the File
sub-menu, and Alt-D will bring down the Dither
sub-menu.
Image Alchemy 23
As you move through various options in the sub-
menus, a short help message will appear on the
bottom status line, giving you further
information.
While in the menu system, pressing Esc will abort
the current menu; if you are being prompted for a
value in a dialog box, Esc will abort the input,
and retain the old value.
Note that some sub-menu entries may be dimmed;
this means that these options cannot be used at
this time. This usually applies to the viewing
and conversion options, which cannot be chosen
without first selecting an input file.
Pressing and releasing the Alt key will take you
up to the menu bar and pull down the first entry
(the File sub-menu, in this case). The left and
right arrow keys will move between the various
sub-menus. At this point, the up and down arrow
keys can be used to highlight a specific option;
pressing Return will select that option.
If you have a mouse connected to your system, you
can point-and-click through the menuing system,
rather than using the keyboard. Clicking an entry
on the menu bar will pull down that menu, and then
clicking on a specific option will actually choose
it. Alternatively, you can move the mouse cursor
to the menu bar, click on a sub-menu category like
File, and while continuing to hold down the mouse
button, select a specific item. When you release
the mouse button, that item will be chosen.
Quitting the To exit the GUI, select Quit from the File sub-
GUI menu. Alternatively, Alt-X will immediately quit
the GUI without going through the menu system.
The File
Sub-Menu
24 Image Alchemy
Select Input Choosing this option will bring up a listing of
Image all the files in the current directory. Using
either the keyboard or the mouse, you can select
the input file on which Alchemy will work on.
There are also listings for the parent directory
and various subdirectories (if any), which allow
you to move around on the drive.
Clicking on the Cancel button or hitting Esc will
abort the selection process, keeping the previous
input file name.
Note that the GUI cannot check for valid image
files, since it would be too time consuming to
have Alchemy process every file in the current
directory. As such, it is possible for you to
select a file which Alchemy itself will not
recognize when a conversion or view is requested.
Select Output Selecting the Output Type will display a scrolling
Type window containing the different image formats to
which Alchemy can output. The up and down arrow
keys will move the highlight bar up and down one
try, and the PgUp and PgDn keys will move the
highlight bar up and down one page. Pressing
Return selects the highlighted output type. The
mouse can also be used to scroll through the
window: clicking on the up and down arrows will
move the highlight bar up and down one entry, and
clicking in the scroll bar above or below the
current location marker will page up and down
through the list.
If you select an output format that has further
options (such as compression type), a further pop-
up menu will ask you to pick an option. Either
typing the highlighted key or clicking on the name
will select that option.
Image Stats After selecting an input file, selecting this
option will display various information for that
file, including the height and width, number of
colours, and compression ratio. Other values may
be displayed, if they are available, such as dots
per inch (DPI), aspect ratio, and gamma.
Image Alchemy 25
Viewing The next four options are for viewing the image
you have selected. View Image will do a standard
8-bit view on an SVGA monitor, displaying only the
center portion of the image if it exceeds maximum
screen resolution. Using the View Scaled option
will work similarly, except it will use Nearest
Neighbor scaling to make sure the entire image
fits on the screen.
If you have an SVGA board and monitor capable of
displaying images in true colour (15-, 16-, or 24-
bits), select View True Color to take advantage of
this. This option will try to view in the highest
resolution possible, while displaying as much of
the image as possible. Note, however, that size
will take priority over resolution. For example,
if you have a 24-bit SVGA card with 1MB of memory,
you should be able to view in 24 bits at 640x480,
and 15 bits at 800x600. So, assuming you have a
640x480 24-bit image, this option will view it in
24 bits. If, however, you have a 700x490 24-bit
image, you will see the whole image, but dithered
to 15 bits. Size takes priority over resolution.
If you have an image larger than what your
card/monitor can display in true colour, using the
View True Color Scaled option will scale the image
so you can view the entire image in true colour.
Show Command Choosing this option will display the parameters
Line which will actually be passed to Alchemy if the
Convert! entry is chosen. This allows you to see
what parameters need to be passed to Alchemy on
the command line to enable various options.
Basic/Expert This menu entry will change, depending on the
Menus current status of the menu system. When first
started, the GUI will default to Basic mode, which
will hide many of the more obscure options Alchemy
deals with. Choosing this option will then force
the GUI to use the full, more advanced menus which
include all possible options.
When the Expert menus are being used, choosing
this option will switch back to the Basic menu
system.
26 Image Alchemy
Convert! This should be the last option you select when
converting an image; use it only after you have
selected all the options you need from the various
other menus.
After choosing this option, you will be prompted
for an output filename, with a default given based
on the output type chosen. To accept, simply type
Return. You may of course modify the default by
typing different names, drives, or directories.
The GUI will then run the Alchemy software,
passing along information about the various
options you have selected in the menu. Since the
GUI swaps almost all of itself out of memory
before calling Alchemy, you do not need to worry
about not having enough memory available for a
particular conversion; if the GUI runs out of
memory, calling Alchemy directly from the command
line will also run out of memory. If this is the
case, contact us about Alchemy/386, which runs in
32-bit protected mode, and hence does not have the
typical memory limitations associated with DOS
applications.
Quit This option will end your GUI session, and return
you to the DOS prompt.
The Resize The options in this sub-menu allow you to control
Sub-Menu various aspects of the output image concerning its
pixel size and DPI information. Along with being
able to specify a certain pixel size, you can also
tell Alchemy to make an image larger or smaller by
some factor. Finally, you can specify the aspect
ratio and DPI information from within this menu.
For further information about the specific options
in this sub-menu, please see Chapter 6.
The Palette The entries in the palette sub-menu allow you to
Sub-Menu control various aspects of the palette and its
generation, including using Heckbert's algorithm,
a uniform palette, or a black and white/greyscale
palette. You can also tell Alchemy to use a
palette from another image, or correct colours in
a CMYK format using an undercolor removal file.
For more detailed information about these topics,
please see Chapter 5.
Image Alchemy 27
The Colors The colors sub-menu primarily allows you to
Sub-Menu specify the number of colours to be used in the
output file. You can also generate a photographic
negative of an image, as well as spiff it using
one of three different algorithms. Finally, from
within this sub-menu, you can modify the input,
output, and palette gamma values.
Please again refer to Chapter 5 for complete
information about these topics.
The Dither The dither menu allows you to select the
Sub-Menu particular dithering algorithm to use. You can
also specify whether you want a serpentine raster
or some amount of perturbation; both of these
options help break up visible patterns left by the
dithering.
For more information about the dithering options,
see Chapter 5.
About The The smooth graphical mouse cursor used in the GUI
Graphical Mouse was implemented with SMDKIT. The Smooth Mouse
Cursor Driver is copyright 1992-1993 by Andy Hakim. For
further information about this software, contact:
Andy Hakim
816 Pecore Street
Houston, TX 77009
USA
+1 713 880 3059
internet: [email protected]
28 Image Alchemy
Image Alchemy 29
4
Output Options
-------------------------------------------------------------------
Introduction The one option which is always required when
running Image Alchemy is the output image file
type. Even if you are just re-sizing an image, or
changing the number of colours in an image,
Alchemy needs to know what type of image you are
creating.
The file types that Image Alchemy supports are
listed below. In addition to the syntax required
to generate the file, any known restrictions or
limitations are listed. If you have trouble
reading an image in one of the file formats we
claim to support please contact us (see Appendix
D, Customer Support).
The common output options consist of a single
letter. The option, like all Alchemy options, is
preceded by a dash, "-". The less common output
options consist of a letter preceded by two
dashes, "--".
With your GUI If you are using the GUI, you can select your
output option from the File sub-menu as described
in Chapter 3.
Variations Some of the output formats have several
variations; in those cases you specify which
variation you want with an optional letter and/or
number after the output option.
30 Image Alchemy
Example The option to generate a Windows Bitmap file is -
w. There are two types of Bitmap files:
uncompressed and Run-Length-Encoded (RLE). To
write out an uncompressed Bitmap file use -w0; to
write out a RLE Bitmap file use -w1 (the default
Bitmap file is uncompressed, so a -w without any
parameter following it would also generate an
uncompressed Bitmap file). Note that Alchemy
allows spaces between the option and parameter, so
typing -w 1 would be the same as -w1.
Variations Be aware that the other options specified on the
command line also affect the type of file that is
generated.
Example Within the Windows Bitmap file type there are 1
bit, 4 bit, 8 bit, and 24 bit files.
Alchemy always generates a file using the best
match of the file type and the output image. So,
in the case of Windows Bitmap files, if the output
image is black and white a 1 bit file is
generated. If the output image is paletted with
16 colours or less a 4 bit file is generated. If
the output image is paletted with more than 16
colours an 8 bit file is generated. And if the
output image is true colour a 24 bit file is
generated.
You can explicitly force any of these file types
by using other Alchemy options. For example, if
you wanted a 1 bit Windows Bitmap file you would
specify -c2 -b -w. To force a 4 bit file use
-c16 -w. To force an 8 bit file use -c256 -w.
And to force a true colour file use -24 -w.
Identifying Image Alchemy identifies the type of file being
image files read by checking various magic numbers and other
information that varies from format to format.
Unfortunately, some formats do not have a magic
number; in those cases Alchemy guesses as to the
image type. It is possible for Image Alchemy to
incorrectly identify an image; if this happens
please contact us.
Image Alchemy 31
MacBinary When reading images, Alchemy automatically
recognizes and reads MacBinary II files (MacBinary
files are generated when you accidently leave
MacBinary mode on when transferring a file from a
Macintosh).
Other Alchemy will preserve as much information in each
information file as possible; this always includes the height
and width of the image and the number of colours
in the image. Some file types include other data,
such as the name of the image, the aspect ratio of
the image, the date the image was created, etc.
Since most of these items are only supported by a
few file formats, Alchemy discards everything but
the height, width, number of colours, gamma,
aspect ratio, and resolution values.
Output Options The individual output options supported by Alchemy
are described in alphabetical order on the
following pages. The descriptions follow the
template given overleaf.
32 Image Alchemy
Name of format -option
Overview of file format.
Syntax Description of syntax.
Parameter Brief description of the parameters. Those
parameters which require a detailed explaination
are further documented under the comments section
below.
Extensions The extensions commonly used for this image
format. When multiple extensions are listed
Alchemy writes files using the first one, but will
check for files using all extensions (in the order
listed). Four letter extensions are skipped on
MS-DOS systems.
Creator The company or individual who created this image
format. Please contact them for more information
on the format.
Used by Programs or types of software that use this image
format.
Variations A list of the variations supported by Image
Alchemy.
Limitations Any known limitations that Image Alchemy has when
reading or writing this image format.
Comments Miscellaneous things of which you should be aware.
Related options Other Alchemy options that affect the reading or
writing of this image format. Note that -8, -24
(and, for some formats, -15, -16, and -32), -c,
and -b options have an effect for most image
formats and are not listed explicitly.
Example Sample conversions involving this image format.
Image Alchemy 33
ADEX --A
ADEX files are used by the ADEX Corporation
ChromaGraph series of graphics cards.
Syntax --A compressionType
Parameter compressionType:
0:None
1:Run Length Coded
The default is None.
Extensions .img
.rle
Creator ADEX Corporation
Used by ADEX ChromaGraph cards.
Variations 4 bit and 8 bit images.
Comments Some ADEX files don't contain a palette; in those
cases there's usually a second ADEX file which
contains the palette to be used. To read those
images that don't have palettes, use the -F false
colour option to read the palette from a separate
file.
Related options -F False colour
Example Convert the file test.gif to an uncompressed ADEX
file called test.img:
alchemy --A test.gif
34 Image Alchemy
Alpha Microsystems BMP -M
Alpha Microsystems BMP files are used by Alpha
Microsystems.
Syntax -M compressionType
Parameter compressionType:
0:None
1:Packed
The default is None.
Extension .bmp
Creator Alpha Microsystems.
Used by Alpha Microsystems workstations.
Variations Reads and writes 1, 4, 8, and 24 bit unpacked and
packed (run-length encoded) RGB images.
Limitations Reading and writing HLS images is not supported.
Comments When reading an image without a palette Alchemy
will generate a gray-scale palette.
Examples Convert the GIF file, bigpict.gif, to an
uncompressed Alpha Microsystems BMP file:
alchemy bigpict.gif -M
Do the same thing, but force a 24 bit image, and
compress the image:
alchemy bigpict.gif -M1 -24
Image Alchemy 35
Autologic --a
Autologic files are black and white or gray-scale
files for use with Autologic typesetting
equipment.
Syntax --a
Extensions .gm
.gm2
.gm4
Creator Autologic, Incorporated
Used by Autologic typesetting equipment.
Variations Graphics modes 2 (black/white) and 4 (gray-scale)
are supported.
Limitations Only the High Speed Interface inline format is
supported.
When reading, images must be preceded by a
Graphics Parameter Block.
Examples Convert the file input.tif to a GM4 file called
output.gm4:
alchemy --a -b input.tif output.gm4
Convert the file input.tif to a GM2 file called
output.gm2:
alchemy --a -b -c2 input.tif output.gm2
36 Image Alchemy
AVHRR --R
AVHRR files are used for satellite image data.
Syntax --R outputType
Parameter outputType
1:IDIDAS Uncompressed
2:IDIDAS Compressed type 1
The default is 1 (IDIDAS Uncompressed).
Extension .sst
Creators National Oceanic and Atmospheric Administration
(NOAA)
National Environmental Satellite Data Information
Service (NESDIS)
Used by IDIDAS
SSTMAP
IMGMAP
Variations Reads 8 and 11 bits per pixel IDIDAS AVHRR files.
Writes 11 bits per pixel IDIDAS AVHRR files.
Limitations Level 1B AVHRR files will be supported at a later
date; please contact us for more information.
Alchemy discards all but the top 8 bits when
reading 11 bit AVHRR files. When writing, the
bottom 3 bits are padded with 0.
Any graphics information is discarded when reading
the file.
Since AVHRR images are always grayscale, Alchemy
assumes the use of the -b and -8 options when
writing a AVHRR file.
Comments AVHRR images contain a lot of information which is
not part of the image data. This information
includes the time and date the image was captured,
the satellite which captured the image, the type
of instrumentation used, etc. When reading AVHRR
images this information is discarded; when writing
AVHRR images 0 is written for all values for which
data is unavailable.
Image Alchemy 37
Example Convert the GOES file, florida.goe, to an
uncompressed IDIDAS AVHRR file:
alchemy --R1 florida.goe
38 Image Alchemy
Binary Information Files (BIF) -B
There are quite a few programs which produce image
files which contain just pixel data. These image
files do not have a header and hence do not
include enough information to allow Alchemy to
read them.
BIF files are a method which can be used to allow
Alchemy to read these images. BIF files can also
be created to allow images to be read by software
which expects images to be just pixels. Since
required information, such as the height and width
of the image, are not present in these files you
must supply it.
Syntax -B
Extensions .bif For ASCII file describing image.
.raw For actual image data.
Creator Handmade Software, Inc.
Used by Image Alchemy
Various image processing software
Variations 24 bit true colour, 8 bit gray-scale, and 1 bit
black and white.
Limitations Paletted files cannot be read in (a work around is
to generate a .PAL file and then false colour the
gray-scale image using the -F option).
Comments BIF files are used to read and write files which
consist entirely of image data. You have to
generate a text file which describes the format of
the data you are trying to read in. This file is
called a BIF file. The format of BIF files is
documented in Appendix E, Binary Information
Files. You then instruct Alchemy to read the
image data by giving it the name of the .BIF file.
Related options -F False colour
Examples Convert the file data to a GIF file:
alchemy data.bif -g
Convert the image helen.pcx to a Binary file (this
will create two files: helen.raw and helen.bif):
Image Alchemy 39
alchemy helen.pcx -B
40 Image Alchemy
Calcomp CCRF --l
Calcomp raster files are used by Calcomp thermal
transfer printers, and Calcomp CCRF files are used
by Calcomp electrostatic printers.
Syntax --l type (lower case l)
Parameter type:
Thermal Transfer Printer:
0:Uncompressed
1:White Space Suppression
2:Run Length Compression
Electrostaic plotter (CCRF):
6:8 bit bytes, 8 bit compression units
7:8 bit bytes, 16 bit compression units
8:8 bit bytes, 32 bit compression units
The default is Thermal transfer, uncompressed.
Extensions .crf
.ccrf
.prn
Creator Calcomp
Used by Calcomp thermal printers and Electrostatic
plotters.
Variations Black and white or CMYK.
Comments If there is only black and white in the image, a 1
bit file will be generated. For colour images,
the black plane will be omitted if it is empty.
See the appendix on undercolour removal files for
information on how to control the black content of
an image.
Example Convert the Targa file image1.tga to a CCRF file
using 16 bit compression units:
alchemy page1.tif --l7
Image Alchemy 41
CALS --c
Computer-aided Acquisition and Logistics Support
(CALS) files are black and white images used by
the US Government as part of their transition to
electronic media.
Syntax --c
Extension .cal
Creator Defense Logistics Agency (DLA)
Used by Department of Defense (DoD)
Variations Reads and writes type 1 (Group 4 raster) CALS
images.
Limitations Document labels, such as document ID and figure
ID, are ignored.
Comments Since CALS files are always black and white,
Alchemy assumes the use of the -b, -8, and -c2
options when writing CALS files.
CALS images are Fax Group IV compressed and are
therefore a good way of storing black and white
line drawings and scans.
Example Convert the TIFF file page1.tif to a CALS file:
alchemy page1.tif --c
42 Image Alchemy
CubicompPictureMaker --P
Cubicomp PictureMaker files are used in broadcast-
quality three dimensional modelling and animation.
Syntax --P type
Parameter type:
0: allow any size image
1: adjust image to 512 x 488
The default is 0.
Extension .r8 (Red channel image data)
.g8 (Green channel image data)
.b8 (Blue channel image data)
.a8 (Alpha channel image data [optional)
Creator Cubicomp Corp.
Used by Cubicomp PictureMaker
Variations Reads and writes 24 bit true colour images.
Limitations If an alpha channel exists, it will be ignored.
8-bit paletted PictureMaker files are unsupported.
Comments This format is not the same as IBM Picture Maker.
The option for adjusting the image size to 512 x
488 was added because Cubicomp PictureMaker does
not work with images which are not of this exact
size. If either the X or Y dimension is larger
than 512 or 488, respectively, that dimension will
be truncated. If either dimension is smaller than
512 or 488, the image will be padded on the right-
hand side or bottom, as necessary, with black.
PictureMaker images have either three or four
separate files per image: a red, green, blue, and
optional alpha channel. You specify the name of
the .r8 file and Alchemy automatically generates
the name of the .g8 and .b8 files
When writing a PictureMaker file Alchemy will
overwrite, without warning, existing .g8 and .b8
files.
Image Alchemy 43
Example Convert the 24-bit JPEG image stones.jpg to
PictureMaker files:
alchemy --P stones.jpg
44 Image Alchemy
Dr. Halo CUT --C
Dr. Halo CUT files are used by various MS-DOS
based paint software.
Syntax --C
Extension .pal (palette and header)
.cut (pixel data)
Creator Media Cybernetics
Used by Dr. HALO III Paint Package
HALO Desktop Imager
Variations 8 bits per pixel
Comments Dr. Halo CUT images are actually two files. You
specify the name of the .cut file and Alchemy
automatically generates the name of the .pal file.
When writing a Dr. Halo CUT file Alchemy will
overwrite, without warning, existing .pal files.
Examples Convert the image test.pcx to a Dr. Halo CUT file:
alchemy test.pcx --C
Image Alchemy 45
Encapsulated PostScript (EPS) -e
EPS files are a subset of PostScript; they may be
included by other PostScript files without
requiring that the importing software be able to
interpret the file.
Syntax -e previewType
Parameter previewType:
0:None
1:Device independent
2:TIFF
The default is device independent.
Extensions .epsi
.epi
Creator Adobe Systems, Inc.
Used by PostScript printers
Variations Gray-scale, RGB, and indexed images.
Limitations Alchemy can only write, not read, EPS images.
Comments If the output is gray-scale, it will work with any
PostScript device. If it's true colour, then the
CMYK extensions or a level 2 device is required.
For paletted files, a level 2 device is always
required.
Examples Convert the file input.gif to a colour EPS file
called input.eps which will not require level 2
PostScript (but will require CMYK extensions),
with no preview:
alchemy -e0 -24 input.gif
Convert the file input.gif to a gray-scale EPS
file called gray.eps, with a device independent
preview:
alchemy -e -b input.gif gray.eps
46 Image Alchemy
ER Mapper Raster --m
ER Mapper files are used by ER Mapper satellite
image analysis software.
Syntax --m
Extensions .ers for header data
. for pixel data
Creator Earth Resource Mapping
Used by ER Mapper
Variations Reads and writes single channel and 3 channel
images.
Limitations Alchemy cannot read 2 channel or 4 or more channel
images without using the -Z option (see the
comments section below for more information).
Comments ER Mapper files are actually two files, one with
the extension .ers and the other without any
extension. The .ers file contains header
information and the non-extensioned file contains
the actual image data. You specify the name of
the .ers file and Alchemy automatically generates
the name of the other file.
When writing a ER Mapper file Alchemy will
overwrite, without warning, existing ER Mapper
image data files.
Using the -Z option it is possible to select a
single channel or 3 channels when reading a multi-
channel ER Mapper image. To use the -Z option
follow it with a single number to indicate which
channel is to be read as a grey-scale image or
three numbers to indicate which channels are to be
read as 24 bit colour image. See the example
section below for details.
Example Convert the Sun Raster file earth.ras to an ER
Mapper file:
alchemy earth.ras --m
Image Alchemy 47
The ER Mapper file Landsat_TM_year_1991.ers
contains 7 bands these examples show various ways
to read selected bands out of the image:
Convert the first band in the image to a
grayscale Sun Raster file.
alchemy Landsat_TM_year_1991.ers -Z 1 -s
Convert the fifth band in the image to a
grayscale Sun Raster file.
alchemy Landsat_TM_year_1991.ers -Z 5 -s
Convert the the image to a 24 bit, colour Sun
Raster file, using band 2 as the red channel, band
7 as the green chanel, and band 3 as the blue
channel.
alchemy Landsat_TM_year_1991.ers -Z 2 7 3 -s
48 Image Alchemy
Erdas LAN/GIS --e
Erdas files are used by Erdas image processing
software.
Syntax --e
Extensions .lan
.gis
Creator Erdas Inc.
Used by Erdas remote sensing software.
Variations Reads and writes 1 and 3 band files.
Reads 4, 8, and 16 bit files. Writes 8 bit files.
Limitations When writing Erdas files Alchemy does not change
the extension depending on the number of bands in
the image; according to the specification gray-
scale files should have the extension .gis and
true colour files should have the extension .lan.
Alchemy always uses .lan.
Comments 1 band files are read in as gray-scale images.
3 band files are read in as true colour images.
The colour mapping between RGB and bands 1, 2, and
3 is Red=Band 1, Green=Band 2, and Blue=Band 3.
Examples Convert the GIS file texas.gis to a Sun raster
file:
alchemy texas.gis -s
Convert the file satellite.image to a GIS file.
alchemy -b --e satellite.image satellite.gis
Convert the file satellite.image to a LAN file.
alchemy --e satellite.image satellite.lan
Image Alchemy 49
First Publisher ART --F
First Publisher ART files are black and white
images used as clip art by First Publisher.
Syntax --F
Extension .art
Creator Software Publishing Corp.
Used by First Publisher
Variations Black and white, 1 bit per pixel.
Comments Since ART files are always black and white, 1 bit
per pixel, Alchemy assumes use of the -c2 and -b
options when writing them.
Examples Convert the image scan.pcx to a First Publisher
ART file:
alchemy scan.pcx --F
50 Image Alchemy
Freedom of Press --f
Freedom of Press is a PostScript interpreter from
Custom Applications that converts PostScript files
to raster files. The Freedom of Press format is
one of the file types it can create.
Syntax --f
Extension .fop
Creator Custom Applications
Limitations Output only.
Only CMYK 1 bit per component per pixel supported.
Comments Freedom of Press images are actually two files, a
data file and an info file. You specify the name
of the data file and Alchemy automatically
generates the name of the info file. The output
file is normally output.001, output.002, etc.
Alchemy will strip the first part of the name and
replace it with 'info', so if you specified an
output filename of output.005 there will be
another file created called info.005. If you
don't specify an extension, Alchemy will use .fop,
so you'll get two files named filename.fop and
info.fop. Alchemy will overwrite info files
without warning.
Related options -C Undercolour removal
Example Convert the file image.tga to a Freedom of Press
image called output.003 and info.003, controlling
the undercolour removal process using sample.ucr,
scaling the image to 2500 pixels across (and
scaling proportionately vertically) using nearest
neighbor scaling, and conserving memory:
alchemy --f -Csample.ucr -X2500 -+ -$
image.tga output.003
Image Alchemy 51
GEM VDI Image File --g
VDI files are files that were developed by Digital
Research to use with GEM.
Syntax --g
Extension .img
Creator Digital Research Inc.
Used by GEM
Variations Reads 1-8 bit grayscale and 3 and 4 bit colour
files.
Writes 1, 3, and 4 bit grayscale and 3 and 4 bit
colour files.
Limitations The support for colour and multiple bit grayscale
GEM files is not very universal. Therefore make
sure the application you are using to read the GEM
files can in fact handle them.
Alchemy defaults to writing out a 1 bit, black and
white GEM file. You can explicitly force a 3
plane colour file by use of the -c8 option and a 4
plane colour file by use of the -c16 option (you
may add a -b to write a grayscale file instead of
a colour file).
Comments Because colour GEM files have only 3 or 4 bits of
information and no palette support the quality is
generally not very good for scanned images. The
GEM format seems to have been designed for line
drawings.
Examples Convert the image scan.pcx to a black and white
GEM file:
alchemy scan.pcx --g
Convert the image bigscan.tga to a 640x480, 8
colour GEM file, using nearest neighbor scaling
and type 2 dithering:
52 Image Alchemy
alchemy -c 8 --g bigscan.tga -X640
-Y480 -d2
Do the same thing but write an 8 shade grayscale
file with no dithering:
alchemy -c 8 --g bigscan.tga -X640
-Y480 -d -b
Image Alchemy 53
GIF -g
GIF files were originally developed by CompuServe
as a machine independent image file format. GIF
files are clearly the most popular way of storing
8 bit, scanned or digitized images. In addition
the compression ratio achieved by GIF files is
usually better than any other 8 bit format in
common use. GIF89A files were introduced in 1990
as a method for including text and simple
animations.
Syntax -g version
Parameter version:
0: GIF87A
1: GIF89A
The default is GIF87A.
Extension .gif
Creator CompuServe, Incorporated
Used by CompuServe
Everyone
Variations Reads 1 through 8 bit GIF87A and GIF89A
interleaved and non-interleaved files.
Writes 1 through 8 bit GIF87A and GIF89A non-
interleaved files.
Limitations When reading GIF89A files only the first image in
the file is read. Any text, overlays, pauses,
palette changes, etc. are ignored.
Because GIF files only store the size of the
palette to the nearest power of 2 the exact
palette size is lost when converting to and from
GIF files. For example, if you convert a 240
colour Sun Raster file to a GIF file and back to a
Sun Raster file the resulting Sun Raster file will
have 256 colours.
54 Image Alchemy
Comments When writing a file you probably want to use the
GIF87A variation, since the GIF89A extensions
aren't necessary to store single images and a lot
of other software still can't read GIF89A images.
The only advantage to GIF89A is that the aspect
ratio of the image is preserved (GIF87A does not
have a provision for storing aspect ratio).
The GIF format includes a field for storing the
colour to be used for the background when viewing
files. Alchemy does not make use of this value.
Alchemy sets the background colour to the darkest
colour in the palette when viewing files and
organizes the palette such that the first colour
is the darkest colour when writing GIF files, if
the palette is created by Alchemy (you can
override this by using the -z option).
Related options -z Palette Selection
Examples Convert the image test.pcx to a GIF87A image.
alchemy test.pcx -g
Convert the file input.tga to a 16 colour GIF89A
file:
alchemy input.tga -c16 -g1
Image Alchemy 55
GOES --G
GOES files are used for satellite image data.
Syntax --G goesType
Parameter goesType:
0:GARS format
1:McIDAS format
The default is 0 (GARS format).
Extension .goe
Creators The University of Wisconsin
National Oceanic and Atmospheric Administration
(NOAA)
National Environmental Satellite Data Information
Service (NESDIS)
Used by Various satellite image processing software,
including the McIDAS system.
Variations Reads 8, 16, and 32 bits per pixel GOES images.
Writes 8 bits per pixel images.
Limitations When reading 16 and 32 bit images Alchemy discards
all but the top 8 bits of data.
Alchemy discards any calibration data and level
maps when reading images.
Because of difficulty in getting a sufficient
number of test images in the GOES format
(especially the PUT format) reading GOES images
has not been thoroughly tested. If you have any
GOES images which Alchemy does not read correctly
please contact us.
Comments The GARS format is a 7680 bytes per block,
Motorola byte-order, EBCDIC format; the MCIDAS
format is a continuous data, Intel byte-order,
ASCII format.
Since GOES images are always grayscale, Alchemy
assumes the use of the -b and -8 options when
writing a GOES file.
56 Image Alchemy
GOES images contain a lot of information which is
not part of the image data. This information
includes the time and date the image was captured,
the satellite which captured the image, the type
of instrumentation used, etc. When reading a GOES
image this information is discarded; when writing
a GOES image 0 is written for all values for which
data is unavailable.
Examples Convert the Erdas file, florida.gis, into a GOES
GARS image:
alchemy --G0 florida.gis
Do the same thing, but write out a GOES McIDAS
image:
alchemy --G1 florida.gis
Image Alchemy 57
Hitachi Raster Format --h
Hitachi Raster Format (HRF) files are black and
white images used by CADCore.
Syntax --h
Extension .hrf
Creator Hitachi Software Engineering Co., Ltd.
Used by Information and Graphics Systems, Inc. (IGS)
Comments Since HRF files are always black and white,
Alchemy assumes the use of the -b, -8, and -c2
options when writing HRF files.
Example Convert the TIFF file page1.tif to a HRF file:
alchemy page1.tif --h
58 Image Alchemy
HP Printer Command Language (PCL) -P
HP PCL files are used by HP LaserJets and
compatible printers.
Syntax -P compressionType
Parameter compressionType:
0: Uncompressed
1: RLE compressed
2: TIFF compressed
3: Delta Row compressed
10:Landscape, Uncompressed
11:Landscape, RLE compressed
12:Landscape, TIFF compressed
13:Landscape, Delta Row compressed
100:LaserJet 4, Uncompressed
101:LaserJet 4, RLE compressed
102:LaserJet 4, TIFF compressed
103:LaserJet 4, Delta Row compressed
110:LaserJet 4, Landscape, Uncompressed
111:LaserJet 4, Landscape, RLE compressed
112:LaserJet 4, Landscape, TIFF compressed
113:LaserJet 4, Landscape, Delta Row
compressed
The default is uncompressed.
Extension .pcl
Creator Hewlett-Packard Company
Used by HP LaserJet printers
HP compatible laser printers
Variations PCL files are always 1 bit per pixel, black and
white.
Reads and writes uncompressed, RLE compressed,
TIFF compressed, and Delta Row Compressed files.
Reads and writes portrait and landscape files.
Image Alchemy 59
Limitations In addition to raster images, PCL files can
include text and vector graphics information.
When reading Alchemy only pays attention to raster
images in the file and attempts to skip everything
else. See Appendix A, Answers to Frequently Asked
Questions, for further discussion of this.
The only resolutions allowed in PCL files are
75 DPI, 100 DPI, 150 DPI, and 300 DPI (and, in the
case of LaserJet 4 type files, 200 DPI, and
600 DPI )
The X and Y resolution must be the same.
If you specify a non-allowable resolution Alchemy
automatically alters the resolution to the next
higher resolution. For example, if you specify
250 DPI Alchemy will write a 300 DPI PCL file
If no resolution is specified either on the
command line or in the input file Alchemy
automatically choses the smallest resolution which
will allow the entire image to fit on the page.
Comments Since PCL files are always 1 bit, black and white
files, Alchemy assumes the use of the -b, -c2, and
-8 options.
When converting colour or gray-scale images to PCL
you will probably want to scale the output so the
image will be larger than the input image. This
will allow the dithering to preserve more detail
in the image.
PCL files can be used to generate output which can
be printed on HP LaserJet and compatible printers.
The easiest method is to simply generate a .PCL
file and then copy it to the printer by using the
copy command (when using the copy command from MS-
DOS you will have to use a /B to make sure the
entire file is copied to the printer; see the
example below for more information).
60 Image Alchemy
Not all PCL compatible printers can print all
types of compressed PCL file. Specifically,
LaserJet II, IID, and earlier printers can print
only uncompressed PCL files. LaserJet IIp
printers can print only uncompressed and RLE
compressed files. LaserJet III, IIID, IIIp,
IIIsi, and 4 printers can print all types of
compressed PCL files.
In general, the higher the compression type, the
better the compression ratio.
The Landscape option can be used to write a
landscape PCL file. Because of changes in the PCL
format, only LaserJet III and newer printers can
print Alchemy produced landscape PCL files.
It is now possible to write a PCL file directly to
a HP LaserJet or compatible printer. If you use
the name of the device as the output file name
Alchemy will redirect output to that device (for
example, use prn: as the output file name if your
LaserJet is attached to the prn: port) .
Examples Convert the image image.gif to a HP PCL file,
using no compression:
alchemy image.gif -P
Convert the image small.gif to a HP PCL file
called out.pcl with dimensions of 2000 by 2000 at
300 DPI:
alchemy small.gif -P -X2000 -Y2000
-D 300 300 out
Print the image generated by the previous example
(for MS-DOS machines only). The /B is necessary
to tell the copy command that the file is a binary
file:
copy /B out.pcl prn:
Convert the image small.gif to a HP PCL file
called out2.pcl with dimensions of 2000 by 2000 at
300 DPI, using TIFF compression:
alchemy small.gif -P2 -X2000 -Y2000
-D 300 300 out2
Image Alchemy 61
To print the print the image madonna.gif directly
to your Laserjet 4 at the largest resolution,
using Delta Row compression with dithering type
22:
alchemy madonna.gif -P104 -D600 600 -Xb4800 -
YB6600 -+ -d22 prn:
To print the print all the TIFF files in the
current directory directly to a LaserJet 2:
alchemy *.tif -P prn:
62 Image Alchemy
HP Raster Transfer Language (RTL) --r
RTL files are used by HP colour raster printers
and plotters.
Syntax --r type
Parameter type:
0: PaintJet
1: HP7600 uncompressed
2: HP7600 PackBits compression
3: HP7600 planar uncompressed
4: HP7600 planar PackBits compression
5: HP7600 planar Group III compression
6: on the fly uncompressed
7: on the fly rle
10: NovaJet
The default is HP7600 PackBits compression.
Extension .rtl
Creator Hewlett-Packard Company
Used by HP raster plotters and printers including
PaintJets and HP 7600 Series plotters.
Variations CMYK, 1 bit per component per pixel.
Blake and white, 1 bit per pixel.
Limitations Output only.
Image Alchemy 63
Comments Compression types 6 and 7 are equivalent to types
1 and 2 except they tell the plotter it may plot
the data as received instead of waiting for the
entire image. This is useful on the DesignJet
plotters which have small buffers compared to the
imageable area.
The NovaJet option cause Alchemy to create RTL
files which are compatible with NovaJet plotters.
Alchemy will generate a colour RTL file unless the
input file is black and white or grayscale or the
-b option is specified as part of the conversion.
RTL files can be used to produce output which can
be printed on HP colour printers and raster
plotters. The file can be printed by sending the
file to the plotter. There is no additional setup
required for the PaintJet. HP7600 series plotters
should be in HP-GL/2 mode best results will
generally be achieved with compensation off. To
get colour plots from the HP7600 series the
plotter must be in 4 or 5 pass mode. The file
must be sent to the printer/plotter in binary mode
(for MS-DOS systems, use the /B option with the
copy command).
If the input is black and white, you probably want
to do the conversion without an undercolour
removal file and with dithering off. See below
for an example.
If the input is gray-scale, you probably do want
to use an undercolour removal file to perform
density correction, but with 100% black removal
(the black removal tables should contain 0 through
255, increasing by one each line) so that the
output won't contain cyan, magenta, or yellow.
The sample directory on the distribution diskette
has a UCR file called gray.ucr which has 100%
black removal.
Related options -C Undercolour Removal File
-d Specify dither type
Examples Convert the black and white image test.wpg to a
RTL file for a PaintJet called test.rtl, not using
a UCR file and with dithering off:
alchemy --r0 -d0 test.wpg
64 Image Alchemy
Convert the file image.tga to a RTL file for a
PaintJet called image.rtl, using the undercolour
removal file sample.ucr:
alchemy --r0 -Csample.ucr image.tga
Convert the file image.tga to a planar RTL file
called image.rtl using PackBits compression,
controlling the undercolour removal process using
sample.ucr, scaling the image to 3000 pixels
across using good quality scaling, preserving the
aspect ratio (by proportionately scaling the image
vertically), and conserving memory:
alchemy --r4 -Csample.ucr -Xb3000 -+ -$
image.tga
Plot the image generated by the previous example
(for MS-DOS machines with the plotter connected to
a port which is mapped to prn:):
copy /b image.rtl prn:
Image Alchemy 65
HP-48sx Graphic Object (GROB) --H
Graphic Object files are used by HP-48sx
calculators.
Syntax --H type
Parameter type:
0: Binary
1: ASCII
The default is Binary.
Extension .grb
.asc
Creator Hewlett-Packard Company
Used by HP -48sx calculators.
Variations Black and white, 1 bit per pixel.
Examples Convert the image madonna.gif to a ASCII HP-48sx
GROB file
alchemy madonna.gif --H 1
66 Image Alchemy
HSI JPEG --j
The HSI JPEG format is a variation of the JPEG
format that was designed by Handmade Software to
better compress paletted images. Paletted images
often have large areas where the image consists of
1 or 2 colours; JPEG compression does a poor job
on these sections when compared to LZW
compression. HSI JPEG files are a combination of
JPEG and LZW compression.
Syntax --j
Extension .jpg
Creator Handmade Software, Inc.
Used by Image Alchemy
GIF2JPG (another Handmade Software product)
Variations 8 bit paletted
Comments HSI JPEG files are not compatible with JPEG or
JFIF files. If you intend to transfer files to
other systems do not use this format, use the
standard JPEG format instead (using the -j
option).
Example Convert the file madonna.gif to a HSI JPEG file:
alchemy --j madonna.gif
Image Alchemy 67
HSI Palette -l
PAL files are palettes which are ASCII files that
can be edited with a text editor.
Syntax -l (lower case L)
Extension .pal
Creator Handmade Software, Inc.
Used by Image Alchemy
Variations Palette files are always ASCII files.
Limitations .PAL files contain only a palette.
Comments The format of PAL files is described in
Appendix H.
Related options -f Match image to specified palette
-F False colour with specified palette
Examples Extract the palette from the GIF file madonna.gif:
alchemy madonna.gif -l
Convert the file image.tga to a GIF file, matching
the palette found in standard.pal:
alchemy image.tga -g -f standard.pal
68 Image Alchemy
HSI Raw -r
HSI Raw files are used internally by Image Alchemy
when converting between certain combinations of
image formats. If you are interested in
converting custom format images to be used with
Image Alchemy we suggest using HSI Raw Files.
Syntax -r
Extension .raw
Creator Handmade Software Inc.
Used by Image Alchemy
Variations 8 bit paletted and 24 bit true colour,
uncompressed, not packed.
Comments This format is used internally as temporary files
by Alchemy when doing certain image conversions;
it can also be explicitly read and written. This
format is described in Appendix F.
Examples Convert the file test.lbm to a raw file:
alchemy test.lbm -r
Convert the raw file, test.raw, to a 24 bit Targa
file called output.tga:
alchemy -24 -a test.raw output.tga
Image Alchemy 69
IBM Picture Maker --i
IBM Picture Maker files are used by IBM
presentation software.
Syntax --i
Extension .pic
Creator IBM
Used by IBM Storyboard Live!
Variations Reads and writes 256 colour Picture Maker files.
Limitations 16 colour Picture Maker files are not supported.
Picture Maker images cannot be larger than
640x480.
Comments This is not the same format as Cubicomp
PictureMaker.
256 colour Picture Maker files may be either
320x200 or 640x480. Image Alchemy will write the
smallest variation that the image will fit in,
with the image centered; the borders will be
filled with colour 0.
Examples Convert the PCX file, giraffe.pcx, into an IBM
Picture Maker file:
alchemy --i giraffe.pcx
70 Image Alchemy
IFF/ILBM -i
IFF (Interchange File Format) files are used by
Amiga computers for storing a number of types of
data, including images, text, and music; ILBM
(InterLeaved BitMap) is a type of IFF file used to
store images.
Syntax -i
Extensions .lbm
.iff
.ilbm
Creator Commodore-Amiga Corp.
Used by Amiga
Deluxe Paint
Variations Reads 1 through 8 bit, 24 bit, HAM, and PBM images
Writes 1 through 8 bit and 24 bit images.
Limitations Dynamic Hi-Res images are not supported.
Does not write images in any of the Amiga specific
display modes.
Comments If you're writing an ILBM file for use on an
Amiga, you probably want to write either a
paletted file with 32 colours or a 24 bit file.
24 bit ILBM files can then be converted to one of
the Amiga specific display modes with various
third-party utilities.
Example Convert the file input.pcx to an IFF/ILBM file
called output.lbm with 32 colours:
alchemy -i -c32 input.pcx output.lbm
Image Alchemy 71
Img Software Set --Q
The Img Software Set is a collection of tools for
manipulating graphic images freely available for
various UNIX workstations (see Appendix J for
information on how to get a copy of the Img
Software Set).
Syntax --Q
Extensions .img
.p
.a
Creator Paul Raveling
Used by Img Software Set
Variations Reads and writes 8 bit paletted and 24 bit images.
Limitations Alchemy does not read nor write compressed (.Z)
images. Use the UNIX supplied uncompress program
to decompress those images before reading with
Alchemy.
Example Convert the Sun Raster file test.ras to an Img
Software Set file:
alchemy test.ras --Q
72 Image Alchemy
JPEG/JFIF -j
JPEG is a new type of image file format that uses
a lossy compression technique to achieve high
compression ratios. See Appendix C, JPEG
Compression, for more information.
Syntax -j[coding] quality
Parameters coding:
Specify the type of entropy coding to
perform.
none: default Huffman coding
a: arithmetic coding
h: optimum Huffman coding
quality:
1 through 100 (larger is higher quality)
The default quality is 32.
Extension .jpg
Creator Joint Photographic Experts Group (JPEG)
Used by Lossy compression of photographic images.
Variations Gray-scale images are saved as single channel JPEG
files; colour images are saved as three channel
JPEG files.
Reads and writes baseline JPEG with CCIR-601 YCbCr
colour space, interleaved components, Huffman or
arithmetic coded.
Alchemy can read files with any component sub-
sampling up to 4x4; it always writes 2h:1v 1h:1v
1h:1v.
Alchemy Huffman coded JPEG files comply with the
industry standard `JFIF' interchange format.
Limitations JPEG files are always lossy, which means that the
compressed image is not identical to the original
image. At high quality factors (32 and above)
this loss is generally so slight as to be barely
noticeable. There is no quality factor which is
guaranteed to be lossless.
Image Alchemy 73
Comments By default, Image Alchemy uses a fixed set of
Huffman tables to compress an image. If the -j is
immediately followed by an 'h', Alchemy will
generate a set of custom tables optimized for the
image and quality factor. This usually produces
5-20% better compression (depending on the image
content and quality factor) but requires an
additional pass over the image data, so it takes a
little longer to compress (there's no effect on
the decompression time). Alchemy can also use
arithmetic coding (by specifying an 'a' after the
-j); this will produce 10-20% better compression;
this is at the expense of JFIF compatibility and
it takes a little longer to both compress and
decompress than Huffman coded files.
Quality may vary between 1 and 100; the default is
32. The higher the number the higher the quality
of the image and the lower the compression ratio.
Quality factors below 10 will produce images with
significant loss of quality.
JPEG files are based on the Joint Photographic
Experts Group (JPEG) CD 10918-1 draft standard.
Since JPEG compression was designed for use with
continuous tone images (such as those produced by
a scanner or digitizer), poor results can be
expected when compressing line drawings.
Related options -q Apply Smoothing when decompressing a JPEG
image.
Because JPEG compression works on 8x8 pixel blocks
there may be discontinuities at the edges of these
blocks producing block artifacts. Smoothing
attempts to reduce these artifacts. Smoothing is
really only necessary at very low quality settings
(less than 10); even then the effects of smoothing
are not particularly significant.
Examples Convert the file photo.tga to a JPEG file called
photo.jpg, using a high quality setting:
alchemy -j70 photo.tga
Convert the file photo.tga to a JPEG file called
photo.jpg, using a low quality setting and
generating optimum Huffman tables:
alchemy -jh10 photo.tga
74 Image Alchemy
Convert the JPEG file, lores.jpg, to a PCX file
using smoothing:
alchemy lores.jpg -p -q
Image Alchemy 75
Jovian VI --J
Jovian VI files are created by the Jovian Logic
video capture boards.
Syntax --J
Extensions .vi
Creator Jovian Logic Corp.
Used by Jovian Logic
Variations Reads 1, 4, 6, and 8 bit gray-scale images, 4 and
8 bit colour paletted images, and 16 and 24 bit
true colour images.
Writes 8 bit gray-scale, 4 and 8 bit colour
paletted images, and 16 and 24 bit true colour
images.
Limitations Reads files with 6 and 8 bit palettes, always
writes 6 bit palettes.
Gray-scale files are always 8 bit.
Comments When writing a VI file the palette always starts
at 0, but will not necessarily be black (which is
the way that Jovian VI files are written).
Example Convert the GIF file, test.gif, to a 16 colour VI
file:
alchemy test.gif --J -c16
76 Image Alchemy
Lumena CEL --L
Lumena CEL files are used by Time Arts software.
Syntax --L
Extension .cel
Creator Time Arts
Used by Lumena
Variations Reads and writes 15 and 32 bit images.
Limitations The Alpha channel in 32 bit images is ignored.
Example Convert the file test.tga to a Lumena CEL file:
alchemy --L test.tga
Image Alchemy 77
Macintosh PICT/PICT2 -m
PICT files were created by Apple Computer as a
common format for Macintosh applications to use.
Virtually every Macintosh application can use PICT
files.
Syntax -m macBinary
Parameters macBinary:
0:do not write a MacBinary file
1:write a MacBinary file
The default is to not write a MacBinary file.
Extensions .pict
.pic
Creator Apple Computer, Inc.
Used by Macintosh computers
Variations Reads 1, 2, 4, 8, 16, and 32 bit PICT and PICT2
images
Writes 1, 2, 4, 8, and 32 bit PICT2 images.
Limitations Only pays attention to pixMaps in the image;
attempts to skip everything else.
Comments Due to the enormous number of options allowed in
PICT files, reading PICTs may not always work.
See Appendix A, Answers to Frequently Asked
Questions, for more information.
Adding a MacBinary header to a MacPaint file is
useful if transfering the file to a Macintosh
computer over by modem. The MacBinary header will
allow the Macintosh to automatically recognize the
file as a MacPaint file.
Example Convert the file input1.gif to a Mac PICT file
called input1.pic:
alchemy -m input1.gif
78 Image Alchemy
MacPaint --t
MacPaint files are black and white images used by
Macintosh computers.
Syntax --tmacBinary
Parameters macBinary:
0:do not write a MacBinary file
1:write a MacBinary file
The default is to not write a MacBinary file.
Extensions .mac
Creator Apple Computer, Inc.
Used by Macintosh computers
Variations 1 bit, black and white.
Limitations MacPaint images are always 576x720 pixels. If you
attempt to write a MacPaint image which is larger,
Alchemy will report this as an error. If you
write an image which is smaller Alchemy will pad
the image with white space along the right-hand
side and bottom.
Because MacPaint images are always black and
white, the -c2, -8, and -b options are assumed
when writing an image.
Comments Adding a MacBinary header to a MacPaint file is
useful if transfering the file to a Macintosh
computer over by modem. The MacBinary header will
allow the Macintosh to automatically recognize the
file as a MacPaint file.
Example Convert the file input1.gif to a MacPaint file
called input1.pic:
alchemy --t input1.gif
Image Alchemy 79
MTV Ray Tracer --M
MTV files are used by the MTV RayTracer, a public
domain ray tracer for Suns and other workstations.
Syntax --M
Extension .mtv
Creator Mark T. VandeWettering
Used by MTV Raytracer
Variations 24 bit true colour.
Comments MTV is a public domain ray-tracer available free
of charge via anonymous ftp from
drizzle.cs.uoregon.edu or via floppy disk from us.
Example Convert the file spheres.img to a MTV file:
alchemy spheres.img --M
80 Image Alchemy
Multi-Image Palette -L
This option will generate an optimum palette for a
variable number of images. This is useful for
finding a common palette where multiple images are
used (animations, for instance), without resorting
to a uniform palette.
Syntax -L filename
Parameters filename is the name of the palette file which
will contain the optimized palette for all of the
images.
Extension .pal
Creator Handmade Software, Inc.
Used by Image Alchemy
Variations Palette files are always ASCII files.
Limitations .PAL files contain only a palette.
Comments The format of PAL files is described in
Appendix H.
Related options -f Match image to specified palette
-F False colour with specified palette
Examples Generate an optimum palette for all GIF files in
the current directory:
alchemy *.gif -L
Image Alchemy 81
OS/2 Bitmap (BMP) -O
OS/2 BMP files are used by IBM OS/2 2.0.
Syntax -O compressionType (Uppercase letter o)
Parameter compressionType:
0:None
1:RLE
The default is none.
Extension .bmp
Creator IBM Corp.
Used by OS/2 2.0
Variations Reads 1, 4, 8, and 24 bit RGB (raw), RLE4, and
RLE8 files.
Writes 1, 4, 8, and 24 bit RGB (raw), RLE4, and
RLE8 files.
Comments
Examples Convert the image test.jpg to a OS/2 BMP file:
alchemy test.jpg -O
82 Image Alchemy
PCPAINT/Pictor Page Format -A
The Pictor format was designed so that an image
could be loaded into an IBM graphics adapter very
quickly; it does this by almost exactly
duplicating the organization of the graphics
adapter memory. This makes the format hardware
dependent.
Syntax -A type
Parameter type:
0:320x200x4 CGA*
1:320x200x16 PCjr/Tandy*
2:640x200x2 CGA*
3:640x200x16 EGA
4:640x350x2 EGA
5:640x350x4 EGA
6:640x350x16 EGA
7:720x348x2 Hercules*
8:640x350x16 VGA
9:320x200x16 EGA
10:640x400x2 AT&T/Toshiba*
11:320x200x256 VGA/MCGA
12:640x480x16 VGA
13:720x348x16 Hercules InColor*
14:640x480x2 VGA/MCGA
15:800x600x2 EGA/VGA
16:800x600x16 EGA/VGA
17:640x400x256 SVGA
18:640x480x256 SVGA
19:800x600x256 SVGA
20:1024x768x2 SVGA
21:1024x768x16 SVGA
22:360x480x256 VGA
23:1024x768x256 SVGA
The default is 640x480x256 SVGA.
*These modes are not yet supported.
Extension .pic
.clp
Creator John Bridges
Used by PCPAINT
GRASP
Image Alchemy 83
Variations There are variations for most IBM and third party
graphics adapter display modes.
Limitations Only the EGA and VGA modes are supported at this
time. Text modes are not supported.
Comments Some Pictor files do not contain palettes. For
those files Alchemy will default to using a
standard palette appropriate to the display mode
the file was saved in. However, the image may not
use the default palette; in that case you can read
the palette from another file with the -F false
colour option.
Related options -F False colour
Example Convert the file image.pcx to a Pictor file called
image.pic, for 800x600x256 SVGA mode:
alchemy -A19 image.pcx
84 Image Alchemy
PCX -p
PCX files are used extensively by MS-DOS machines.
Originally created by ZSoft for use by their paint
packages, PCX files can be read and written by
almost all MS-DOS paint software and desktop
publishing software.
A new variation of PCX file, DCX, is used by many
MS-DOS fax boards.
PCX files suffer from two problems: the
compression ratio is poor for 8 and 24 bit images
and PCX files are often written out incorrectly;
see the Limitations section below for details.
Syntax -p type
Parameter type:
0:Standard PCX
1:DCX
2:PCJ
The default is standard PCX.
Extension .pcx
Creator ZSoft Corporation
Used by PC Paint
Publisher's Paintbrush
Most paint and desktop publishing software can
read and write PCX files.
Fax board software uses the DCX variation of PCX.
Variations 1, 4, 8, and 24 bits per pixel for standard PCX
files.
1 bit per pixel for DCX files.
8 bits per pixel for PCJ files.
Limitations PCX format files are often written out
incorrectly; Alchemy attempts to figure out what
is wrong and make intelligent decisions (things
Alchemy can deal with include PCX files without
palettes, files missing the last line of image
data, and files with illegal (and incorrect)
combinations of bits per pixel and planes).
Image Alchemy 85
24 bit PCX files are very new and most other
software cannot read them. Therefore, unless you
are sure that the software you are using can read
a 24 bit PCX file, you probably want to use the -8
option to force Alchemy to write a paletted file
when generating a PCX file.
DCX files are multiple page PCX images which are
used by various manufacturers of fax boards and
fax software. Alchemy only reads the first page
of a DCX file. Alchemy always writes single page
DCX files which are black and white.
Comments Because so many software packages can read and
write PCX files we are especially interested in
supporting as many variations as possible. If you
have any PCX files which Alchemy does not read
correctly please contact us.
Since DCX files are always 1 bit, black and white
images, Alchemy assumes the use of -b -c2 -8 when
writing the DCX variation of PCX.
ZSoft recently changed some of the information in
the header of PCX files so they now include image
resolution. Some fax board software makes use of
this information when transmitting PCX or DCX
files as faxes. See the example section below for
an example of how to specify image resolution when
writing a PCX file.
PCJ files are a variation of 256 colour PCX files
which have the palette in a separate file. The
palette file has the extension .p13. Alchemy will
automatically look for the palette file in the
same directory as the PCJ file when reading.
Related options -D Specify image resolution.
Example Convert the GIF file, lush.gif, to a PCX file:
alchemy lush.gif -p
Convert the scanned image, page1.tif, to a DCX
file:
alchemy -p1 page1.tif
86 Image Alchemy
Convert the scanned image, page2.tif, to a DCX
file, specifying an image resolution of 200x100 (a
common resolution for fax images):
alchemy -p1 page2.tif -D 200 100
Image Alchemy 87
PDS --p
PDS labeled images are used by NASA for planetary
images.
Syntax --p
Extensions .ibg
.imq
Creator NASA
Used by NASA distributes collections of planetary images
on CD-ROM in PDS format.
Variations Reads 1 and 8 bit uncompressed and 8 bit first
difference Huffman compressed files.
Writes 8 bit gray-scale uncompressed PDS files.
Limitations PDS images must begin with either an "SFDU_LABEL"
or a "FILE_TYPE" record for Alchemy to be able to
identify it.
Occasionally a PDS labeled image has a palette.
There doesn't seem to be any standard format for
the palette; Image Alchemy handles the palettes
we've encountered.
Any portions of the PDS labels not required to
extract the image, such as longitude and latitude,
are ignored.
Comments Since Image Alchemy only writes gray-scale PDS
images, Alchemy assumes the use of the -b option
when writing PDS files.
Some PDS images actually consist of two files, a
label file and a data file. To read that type
image you should use the name of the label file
and Alchemy will find the data file.
Examples Convert the GOES file, phoenix.goe, into a PDS
labeled image:
alchemy --p phoenix.goe
88 Image Alchemy
Portable BitMap (PBM) -k
The Portable BitMap format was developed by Jef
Poskanzer to allow the transferring of black and
white image files between different workstations.
The PBM format has grown to include black and
white, gray-scale, and true colour images, a large
set of programs to convert various other image
formats to and from PBM, and a set of image
manipulation tools. The PBM tools are available
free of charge (unfortunately, due to their memory
requirements, many are not useable on MS-DOS
machines).
Syntax -k
Extensions .pnm Portable aNyMap (Any of those below)
.pbm Portable BitMap (Black and white)
.pgm Portable GrayMap (Gray-scale)
.ppm Portable PixelMap (True colour)
Creator Jef Poskanzer
Used by Portable BitMap Package
Various workstation graphic programs
Variations Reads and writes 1, 8, and 24 bit RAWBITS (binary)
images.
To write out a PBM file use -b -c2.
To write out a PGM file use -b -c256.
To write out a PPM file use -24.
Limitations When writing a PBM file Alchemy always uses the
.pnm extension (the extension should be changed
based on the type of file being written).
Comments The PBM package is a set of image manipulation
tools which run on various workstations. The
software is available for free via anonymous ftp
from expo.lcs.mit.edu as contrib/pbmplus.tar.Z,
ftp.ee.lbl.gov as pbmplus.tar.Z, or via floppy
disk from us.
Examples Convert the file sun.im32 to a PBM file:
alchemy sun.im32 -k -b -c2
Convert the file sun.im32 to a PGM file,
overwriting any existing sun.pnm file:
Image Alchemy 89
alchemy sun.im32 -k -b -c256 -o
Convert the file sun.im32 to a PPM file called
image77:
alchemy sun.im32 -k -24 image77 -.
90 Image Alchemy
Puzzle --U
The Puzzle format is used by the UNIX supplied
Puzzle program
Syntax --U
Extensions .pzl.puzzle
.cm
Creator Unknown
Used by The puzzle program.
Variations 8 bits per pixel
Example Convert the file einstein.im8 to a Q0 file:
alchemy einstein.im8 --q
Image Alchemy 91
Q0 --q
The Q0 format is apparently commonly used by
various Japanese scanning, painting, and viewing
software to store 24 bit images. Handmade
Software has no information other than a basic
description of the format and some sample images;
if you have further information on the Q0 format
please contact us.
Syntax --q
Extensions .q0 For pixel data
.rgb For pixel data
.fal For image header information
Creator Unknown
Used by Various Japanese image processing software.
Variations 24 bits per pixel
Comments Q0 files are actually two files, one with the
extension .rgb or .q0 and the other with the
extension .fal. The .rgb or .q0 file contains the
actual image data and the .fal file contains the
header information (primarily the height and width
of the image). You specify the name of the .rgb
or .q0 file and Alchemy automatically generates
the name of the .fal file.
When writing a Q0 file Alchemy will overwrite,
without warning, existing .fal files.
Example Convert the file dogcow.gif to a Q0 file:
alchemy dogcow.gif --q
92 Image Alchemy
QDV --D
The QDV format is used by Giffer, a Macintosh
program which displays and converts image files.
Syntax --D
Extension .qdv
Creator Steve Blackstock
Used by Giffer
Variations QDV files are always 8 bits per pixel.
Comments Giffer is a great shareware (Beerwaretm, actually)
program for the Macintosh that converts between
various image file formats and allows viewing of
graphics files.
Since QDV files are always paletted, Alchemy
assumes the use of the -8 option when writing QDV
files.
Example Convert the file input.tga to a qdv file:
alchemy input.tga --D
Image Alchemy 93
QRT --T
QRT files are generated by the QRT Ray Tracer, a
public domain ray-tracer for Amiga, Macintosh, and
IBM PC computers.
Syntax --T
Extension .raw
Creator Steve Korn
Used by QRT Ray Tracer
Variations 24 bits per pixel
Comments Since QRT files are always true colour, Alchemy
assumes use of the -24 option.
Example Convert the file spheres.gif to a QRT file called
spheres.raw:
alchemy --T spheres.gif
94 Image Alchemy
RIX -R
RIX files are colour files developed by ColoRIX to
use with their paint software.
Syntax -R
Extension .scx
.rix
Creator RIX Softworks, Inc.
Used by ColoRIX software
Variations Reads and writes Type 0 (8 bits per pixel) and
Type 4 (4 bits per pixel) images.
Limitations We would like to add support for Type 1 and Type 2
images but we haven't been able to find any; if
you have some please contact us.
Comments A type 0 file will be written if there are more
than 16 colours in the image; otherwise a type 4
file will be written.
Examples Convert the file test.gif to a RIX file:
alchemy test.gif -R
Image Alchemy 95
Scodl --s
Scodl files are used by Agfa/Matrix slide
recorders.
Syntax --s
Extension .scd type
Parameter type:
0: Non-scalable image (pre MVP version 4.2)
1: Scalable image (MVP version 4.2 or later)
The default is 0 (Non-scalable).
Creator Agfa Corporation / Matrix Instruments Inc.
Used by Agfa/Matrix slide recorders
Variations Writes 8 and 24 bit run-length coded (RLC) images.
Limitations Output only.
Comments Agfa/Matrix made significant changes to the Scodl
file format when they introduced version 4.2 of
the MVP and Conductor software in 1992. Old
version Scodl files could not be scaled by the MVP
software; new version Scodl files can be scaled
but only work the newer version of the MVP and
Conductor software.
96 Image Alchemy
Scalable Scodl images have the advantages that
they do not have to be scaled to a specific output
resolution and are therefore generally smaller
than pre-scaled Scodl images. They will can also
be imaged on a film recorder with any output
resolution or previewed on a monitor.
The disadvantage of scalable Scodl images is that
you must be using at least Scodl MVP version 4.2
and the Scodl MVP software does not perform very
high-quality scaling. In particular, the MVP
software only does pixel replication scaling when
increasing the size of an image (this corresponds
to type 'a' scaling in Alchemy) and pixel
averaging when reducing the size of an image
(corresponding to Alchemy 'b' scaling).
Note that Alchemy pays attention to the aspect
ratio or dots per inch information specified as
part to command line or present in the original
image when converting to a Scodl scalable image.
Therefore you should insure that this information
is correct when writing a Scodl scalable image.
When writing Pre 4.2 Scodl files the image should
be scaled up to either 2000x1366 or 4000x2732 to
fill the slide.
There are some limitations with the current
version of the MVP software driver supplied by
Agfa/Matrix:
24 bit Scodl files are not correctly interpreted
by the MVP driver version 4.1 and earlier. 8 bit
images are correctly interpreted.
When sending very large images to the background
MVP driver you must be using version 4.0 or later
and have lots of EMS memory (4 Megabytes is
recommended). When using the foreground MVP
program turning on disk caching is necessary.
Example Convert the file picture.im32 to a Scodl file
using high quality scaling and preserving the
aspect ratio:
alchemy --s -Xc2000 -Yc1366 -+ picture.im32
Image Alchemy 97
Silicon Graphics Image (SGI) -n
Silicon Graphics Image files are used by Silicon
Graphics workstations.
Syntax -n compressionType
Parameter compressionType:
0:Verbatim (uncompressed)
1:RLE compressed
The default is 0 (Verbatim).
Extension .sgi
Creator Silicon Graphics, Inc.
Used by Silicon Graphics workstations.
Variations Reads and writes 1, 8 (gray-scale), and 24 bit
verbatim (uncompressed) and RLE files.
Comments Only gray-scale images may be 8 bit files.
Alchemy will automatically switch to 24 bit mode
when writing a colour image.
Example Convert the Sun raster file sun.im8 to a SGI file
called sgiout:
alchemy -n sun.im8 sgiout -.
Do the same thing, but write out a RLE compressed
SGI file:
alchemy -n1 sun.im8 sgiout -.
98 Image Alchemy
SPOT Image --S
SPOT Image files are high-resolution satellite
images produced by SPOT Image Corporation.
Syntax --S
Extensions For GIS (tape) format:
.hdr (For image header information)
.bil (For pixel data)
.clr (For palette data [optional])
For CCT (CD-ROM) format:
.dat
Creator SPOT Image Corp.
Used by SPOT Image Corp.
Variations 8 bits per pixel for GIS (tape) format files
8 and 24 bits per pixel for CCT (CD-ROM) format
files
Limitations Only GIS (tape) format images are written.
Comments SPOT Image GIS (tape) images are actually three
files. You specify the name of the .hdr file and
Alchemy automatically generates the name of the
.bil and .clr files.
If no palette file (.clr file) exists Alchemy will
assume the image is grayscale.
There may also be a statistics file with a .stx
extension, but Alchemy ignores this file.
When writing a SPOT file Alchemy will overwrite,
without warning, existing .bil and .clr files.
When reading a CCT (CD-ROM) format image specify
the complete path and name of the image file. For
example: alchemy l:\scene04\imag_04.dat -g will
convert the scene 4 image to a .gif file.
Image Alchemy 99
Examples Convert the Erdas file, phoenix.lan, to a SPOT
Image file:
alchemy --S phoenix.lan
100 Image Alchemy
Stork -K
Stork files are CMYK images used by Stork's colour
proofing machines.
Syntax -K compressionType
Parameter compressionType:
0:None
1:Run length coded
The default is none.
Extensions .idx Index file
.pre Image data
.tab Colour lookup table
Creator Stork Colorproofing B.V.
Used by Stork Colorproofing machines
Variations Reads and writes 32 KCMY, 32 KCMY RLC, 16 CLU, and
16 CLU RLC images (type 100, 101, 300, and 301,
respectively).
Limitations Alchemy can't write paletted files with more than
256 colours.
When reading paletted files with more than 256
colours they are treated as true colour.
Comments Stork images are stored in two or three files
(depending on whether or not there's a colour
lookup table associated with the image). The
filename given to Alchemy should be the name of
the data file (normally with a suffix of .pre);
Alchemy will generate the names of the other files
by stripping the extension and appending .idx for
the index file and .tab for the colour lookup
table (if any). Alchemy will overwrite existing
.idx and .tab files without warning when creating
Stork files.
Related options -C Undercolour Removal File
Example Convert the file image.tga to an uncompressed
Stork image called image.pre and image.idx, using
the undercolour removal file sample.ucr:
alchemy -K -Csample.ucr image.tga
Image Alchemy 101
Sun Icon --N
Sun Icon files are used by Sun Microsystems
workstations.
Syntax --N
Extensions .icon
.ico
Creator Sun Microsystems, Inc.
Used by Sun workstations
Variations 1 bit, black and white.
Example Convert the sun raster file icon.im1 to a sun icon
file called program.ico:
alchemy -s icon.im1 program.ico
102 Image Alchemy
Sun Raster -s
Sun Raster files are used by Sun Microsystems
workstations.
Syntax -s compressionType
Parameter compressionType:
0:None
1:Run length compression
The default is None.
Extensions .rast
.ras
.im
.im1
.im8
.im24
.im32
Creator Sun Microsystems, Inc.
Used by Sun workstations
Variations Reads 1, 8, 24, and 32 bit Standard, BGR, RGB, and
Byte Encoded (RLE) files.
Writes 1, 8, 24, and 32 bit Standard files, and 1
and 8 bit Byte Encoded (RLE) files.
Limitations For a short time a version of the PBM toolkit
wrote Sun Raster files which had the wrong RGB
order. Unfortunately there seem to be many images
which were generated with this incorrect RGB
order. Please be aware that Alchemy's Sun Raster
reading and writing capability has been
extensively tested and compared to various other
tools; the RGB order we use is correct.
Comments Sun Raster files are normally not compressed and
so take up lots of disk space.
There is no standard extension for Sun Raster
files; the extensions that Alchemy uses seem to be
the most common.
Example Convert the SGI file sgiout to a sun raster file
called sun.im8:
alchemy -s sgiout sun.im8
Image Alchemy 103
Do the same thing, but write out a compressed sun
raster file:
alchemy -s1 sgiout sun.im8
104 Image Alchemy
Tagged Interchange File Format (TIFF) -t
TIFF is designed to be a universal raster image
format. It's very popular with desktop publishing
packages.
Syntax -t compressionType
Parameter compressionType:
0:None
1:LZW
2:PackBits
3:Group III Fax
4:Group IV Fax
5:CCITT RLE
The default is LZW Compression.
Extensions .tiff
.tif
Creator Aldus Corp.
Microsoft Corp.
Used by Various desktop publishing and scanning software.
Variations Reads TIFF class B, G, R, and most class P files.
Reads 1, 4, 8, 12, 24, and 32 bit images (ignoring
the alpha channel for 32 bit images).
Input compression types supported are raw, LZW,
PackBits, Group III fax, Group IV fax, CCITT RLE
(byte and word aligned), NeXT, Thunderscan, PICIO,
and SGI RLE.
Writes class B, G, P, and R files, depending on
the input file and options specified.
Writes 1, 4, 8, and 24 bit images.
Limitations Class P TIFF files can only be read if they have
1, 4, or 8 bits per pixel.
Image Alchemy 105
Comments 1,4, and 8 bit output files are paletted unless
the palette is all gray, in which case the output
is a gray-scale file.
If you have TIFF files with 3, 5, 6, or 7 bits per
pixel please contact us.
When writing TIFF files using any of the fax
compression types (Group III, Group IV and CCITT
RLE), Alchemy uses a photometric interpretation of
minIsWhite.
Example Convert the file input.gif to an uncompressed
gray-scale TIFF file called output.tif:
alchemy -t0 -b input.gif output.tif
106 Image Alchemy
Targa -a
Targa files were created to support the line of
Targa graphics cards. The Targa format is popular
with scanners and high end paint packages.
Syntax -a outputType
Parameter outputType:
0:uncompressed
1:Run Length Coded
10:uncompressed, no footer
11:Run Length Coded, no footer
The default is 0 (uncompressed).
Extension .tga
Creator Truevision, Inc.
Used by Various scanning and paint software.
Variations Reads 8, 15, 16, 24, and 32 bit images, ignoring
the alpha channel for 32 bit images.
Writes 8, 15, 16, 24, and 32 bit images, writing
an empty alpha channel for 32 bit images.
Comments 15 and 16 bit output are actually the same except
for one field in the header.
Targa files allow a footer containing additional
information such as aspect ratio. However some
software is unable to read Targa files which have
a footer, so Alchemy allows all valid combinations
to be written. The most common variant for
software to be able to read is 24 bit uncompressed
(specify -a0 and -24).
Example Convert the file input.tif to an uncompressed 24
bit Targa file:
alchemy input.tif -a -24
Convert the file input.tif to an uncompressed 15
bit Targa file called output.tga with no footer:
alchemy -a10 -15 input.tif output.tga
Image Alchemy 107
Utah Raster Toolkit (RLE) --u
The Utah Raster Toolkit is a set of public domain
utilities for manipulating and converting images
for various workstations. The source code is
freely available (see below).
Syntax --u
Extension .rle
Creator The University of Utah
The University of Michigan
Used by Utah RLE toolkit
Variations Reads and writes 1 and 3 channel 8 bits per pixel
files; the Alpha Channel is ignored during
reading.
Limitations While reading, files which are 1 channel and have
either no colour map or a single channel colour
map are assumed to be gray-scale images. The
colour map, if present, will be used as a gamma
correction table.
Files which are 1 channel and have a 3 channel
colour map are assumed to be paletted colour
files.
Files which are 3 channel are assumed to be true
colour.
When writing RLE files Alchemy will generate a 1
channel file with a 3 channel colour map for
paletted images and a 3 channel file with no
colour map for true colour images.
Comments The Utah Raster Toolkit is available free of
charge as pub/urt-3.0.tar.Z via anonymous ftp from
cs.utah.edu, weedeater.math.yale.edu, or
freebie.engin.umich.edu or via floppy disk from
us.
Example Convert the PBM file, image.ppm, to a Utah RLE
file:
alchemy image.ppm --U
108 Image Alchemy
Vivid --I
Vivid is a shareware ray-tracer for MS-DOS
computers.
Syntax --I (upper case i)
Extension .img
Creator Steven B. Coy
Used by Vivid Ray Tracer
Variations Reads and writes 24 bit RLE files.
Comments The Vivid Ray Tracer is a shareware program for
PCs and is available from
Stephen Coy
15205 NE 13th Pl., #2904
Bellevue, WA 98007
Example Convert the file spheres.qrt to a Vivid file:
alchemy spheres.qrt --I
Image Alchemy 109
Windows Bitmap (BMP) -w
Windows BMP files are used by Microsoft Windows.
Syntax -w compressionType
Parameter compressionType:
0:None
1:RLE
10:Write an ICOn file
The default is none.
Extension .bmp
Creator Microsoft Corp.
Used by Microsoft Windows
Variations Reads 1, 4, 8, and 24 bit RGB (raw), RLE4, and
RLE8 files.
Writes 1, 4, 8, and 24 bit RGB (raw), RLE4, and
RLE8 files.
Limitations Several of the programs which claim to read and
write RLE files do not do so correctly; we do not
recommend writing RLE files unless you have
verified that they work with your intended
application.
Comments Microsoft supplied Windows utilities cannot read
nor write RLE4 or RLE8 files.
If you are converting an image to use as wallpaper
on a 16 colour display you will want to match the
palette of the output image to one of the existing
16 colour BMP images supplied with Windows
(chess.bmp, for example). If you do not do this
the wallpaper will not be loaded correctly. See
the example section below.
If you are converting an image to use as wallpaper
on a 256 colour Windows 3.1 display you will want
to reserve the first 8 colours. Use the -c 256 8
option to do this (see below for an example).
This will force the first 8 colours of the palette
to be the standard Windows colours.
110 Image Alchemy
If you are writing a Windows icon (.ico) file you
must scale the image to a width and a height of
16, 32, or 64 pixels (32 being the best choice,
since Windows displays all icons as 32x32). Also,
Windows seems to remap all icons to the standard
16 colours, so the best results can be obtained if
you match the palette of your icons to an existing
icon (see the -f option). If you don't have any
other icons you can also match to one of the 16
colour wallpaper files supplied with Windows.
Alchemy can write a BMP file which contains an
identity palette as specified in the Microsoft
Multimedia Development Kit. These images provide
for quicker bitmap loading when used with the
Multimedia Extensions. A palette identity file
has the first and last 10 palette entries reserved
for 20 system defined colours. Alchemy will write
such an image if you specify -c 246 10 as part of
the command line. Note that ordinarily this would
produce a file which has 246 palette entries, but
in this special case the file will have 256
palette entries (20 fixed by the Windows
specifications and 236 chosen by Alchemy). Note
that you can also specify a number smaller than
246, but the palette will always have 256 colours
(since the last 10 have to occupy positions 246
through 255).
Related options -c Specify number of colours
-f Match to existing palette
Examples Convert the image test.gif to a Windows BMP file:
alchemy test.gif -w
Convert the image test.gif to a 16 colour Windows
BMP file to be used as wallpaper (the file
chess.bmp is supplied with Windows 3.0 (substitute
leaves.bmp when using Windows 3.1); this example
assumes that it is in the current directory):
alchemy test.gif -f chess.bmp -w
Convert the image test.gif to a 256 colour Windows
BMP file to be used as wallpaper with Windows 3.1:
alchemy test.gif -c256 8 -w
Convert the image test.gif to an icon file for use
with Windows 3.1:
Image Alchemy 111
alchemy test.gif -Xb32 -Yb32 -w 10
-f leaves.bmp
Convert the image test.gif to an identity palette
BMP file:
alchemy test.gif -w -c 246 10
112 Image Alchemy
WordPerfect Graphic File -W
WordPerfect files are images which can be imported
into WordPerfect and various other word processors
and desktop publishing programs.
Syntax -W
Extension .wpg
Creator WordPerfect Corp.
Used by WordPerfect
Variations 1 through 8 bits per pixel are supported.
Comments In addition to raster images WordPerfect files may
contain vectors and text information. Such
information is lost when reading WordPerfect
files.
Example Convert the image, newpict.pcx, to a black and
white WPG file:
alchemy newpict.pcx -b -c2 -W
Image Alchemy 113
XBM --b
XBM files are used by the X Windowing System. XBM
files are C source code files which can be read
and written by various X utilities and are
designed to be included in C source code for use
as icons and other bit-mapped graphic images.
Syntax --b
Extensions .xbm
.bm
Creator MIT
Used by The X Windowing system
Variations 1 bit per pixel
Limitations Because .xbm files are actually C source code
files there can be many variations of .xbm files.
Since adding a C preprocessor to Alchemy to handle
all the theoretically allowable .xbm files is
impractical we have instead designed Alchemy to
interchange .xbm files with the PBM utilities and
the X supplied utilities, and to read the sample
.xbm files from Sun Microsystems. If you run
across any .xbm files which Alchemy cannot read
please contact us.
The hotspot field is ignored when reading .xbm
files.
Comments Most of the X supplied utilities (bitmap, for
example) are designed to edit small .xbm images.
Example Convert the file picture.im32 to an XBM file using
high quality scaling and preserving the aspect
ratio:
alchemy --b -Xb64 -+ picture.im32
114 Image Alchemy
XPM --x
XPM files are used by the X Windowing System. XPM
files are C source code files which can be read
and written by various X utilities and are
designed to be included in C source code for use
as icons and other bit-mapped graphic images.
Syntax --x type
Parameter type:
0: XBM similar style
1: XPM3 style
2: XPM2 style
The default is XBM similar style.
Extensions .xpm
.pm
Creator MIT
Used by The X Windowing system
Variations 8 bits per pixel
Limitations Because .xpm files are actually C source code
files there can be many variations of .xpm files.
Since adding a C preprocessor to Alchemy to handle
all the theoretically allowable .xpm files is
impractical we have instead designed Alchemy to
interchange .xpm files with the PBM utilities and
the X supplied utilities, and to read the sample
.xpm files from IBM. If you run across any .xpm
files which Alchemy cannot read please contact us.
Some XPM files contain colour names instead of
color values for some of the colours. The
conversion table of these names into values is in
a file supplied with the X Windowing system called
rgb.txt. When needed Alchemy will look for this
table in the following directories: the current
directory, /usr/lib/X11, $OPENWINHOME, and
/usr/openwin/lib. If your system has the rgb.txt
file in a different location you may have to copy
it to the current directory (its location is
system dependent; ask you system administrator if
you need help finding it).
Image Alchemy 115
Comments The different type XPM files can be identified as
follows:
Type 0:
#define type0_format 1
_
static char *type0_colors[] = {
"a", "#000000",
_
Type 1:
/* XPM */
static char * type1[] = {
"32 20 12 1",
"a c #000000",
_
Type 2:
! XPM2
32 20 12 1
a c #000000
_
When writing an XPM file with less than 27 colours
Alchemy writes 1 character XPM files, otherwise
Alchemy writes 2 character XPM files.
XPM files are usually quite small, therefore many
utilities (the PBM toolkit for example) may have
trouble reading large XPM files.
Example Convert the file picture.im32 to an XPM file using
high quality scaling and preserving the aspect
ratio:
alchemy --x -Xb64 -+ picture.im32
116 Image Alchemy
XWD --w
XWD is the file format used by xwd, the X window
dumping utility.
Syntax --w type
Parameter type:
0: Z type
1: XY type
The default is Z type.
Extension .xwd
Creator MIT
Used by The X Windowing System
Variations Reads 1, 4, 8, and 24 bits per pixel Z format and
1, 4, and 8 bit XY format XWD files.
Writes 1, 8, and 24 bits per pixel Z format and 1
and 8 bit XY format XWD files.
Limitations XY format files are not supported.
Example Convert the XBM file, icon.xbm, to an XWD file:
alchemy icon.xbm --w
Image Alchemy 117
5
General Options
-------------------------------------------------------------------
Introduction General options are options which do not affect
the conversion of the image. They control such
things as the overwriting of existing files and
the way that memory is used.
If you are currently using the Alchemy's menu
interface rather than the command-line, you can
focus on the purpose, comments, and limitations
entries in this chapter.
118 Image Alchemy
Conserve Memory -$
Purpose Use as little memory as possible when converting
images.
Syntax -$ (dollar sign)
Comments Normally Alchemy tries to work on chunks of the
image several lines long to improve performance.
Use of the -$ option will cause it to use the
smallest size chunks possible for the conversion
being performed. On MS-DOS based systems this
will usually allow conversion of larger images
than would otherwise be possible. On UNIX systems
this may reduce paging when converting very large
images.
Example Convert the image giant.tga to a 16 colour TIFF
file conserving memory:
alchemy giant.tga -$ -t -c16
Image Alchemy 119
Display Image Stats -x
Purpose Display image statistics.
Syntax -x
Comments Displays image type, size, number of colours,
aspect ratio, resolution, and compression ratio.
Limitations Cannot be combined with other options.
Example Find out about the image called image.tga:
alchemy -x image.tga
120 Image Alchemy
Do not alter output filename -.
Purpose Disable automatic appending of the output image
type to the output file name.
Syntax -. (period)
Comments By default, if there's no '.' in the output
filename, Alchemy will add an extension indicating
the type of file. If the -. option is specified
no extension will be added.
This is most useful on non-MS-DOS systems where
'.' is not a special character in filenames.
Example Convert the file called infile.gif to a PCX file
called outfile (if you did not use the -. option
Alchemy would automatically change the output file
name to outfile.pcx):
alchemy infile.gif outfile -p -.
Image Alchemy 121
Help -h
Purpose Give you information on how to use Image Alchemy.
Syntax -h option
Parameter option
0: general help
1: general options
2: output formats a-k
3: output formats l-z
4: colour options
5: scaling options
6: display options (MS-DOS Only)
Default is 0, general help
Comments The help information given by this command is only
a summary.
Limitations The help option cannot be combined with any other
options.
Related options -? support and update information
Example Get help on the colour options:
alchemy -h4
122 Image Alchemy
Overwrite -o
Purpose Force Alchemy to overwrite existing files on the
disk.
Syntax -o
Comments Image Alchemy will not overwrite an existing file
unless the -o option is specified.
Limitations The input file name and the output file name
cannot be the same.
Example Convert the file input.tga to a GIF file called
output.gif, overwriting the existing file called
output.gif:
alchemy input.tga -g output.gif -o
Image Alchemy 123
Program information -?
Purpose Give you information on how to get support for
Image Alchemy or inquire about update information.
Syntax -?
Comments Sun-3 and Sun-4 users have to escape the question
mark with a back-slash (instead of -? use -\?).
This is because the UNIX shell will attempt to
perform wildcard expansion on the question mark.
Limitations The information option cannot be combined with any
other options.
Related options -h help with commands
Example Get support information:
alchemy -?
124 Image Alchemy
Quiet -Q
Purpose Suppress all status messages (but not error
messages).
Syntax -Q
Comments This is useful when running Alchemy in the
background on UNIX systems or in batch files on
MS-DOS systems (and you don't want the output of
Alchemy scrolling important messages off of the
screen).
Limitations There is no way to suppress error messages.
Example Convert the file dummy.gif to a PCX file but don't
report any status messages:
alchemy -Q dummy.gif -p
Image Alchemy 125
Warnings --W
Purpose Treat missing input files, unidentifiable input
files, and non-overwriteable output files as a
non-fatal errors.
Syntax --W
Comments When used in conjunction with the Wildcard option
(see below) the Warnings option allows Alchemy to
proceed even when certain error conditions occur.
Specifically, any input files which are missing or
can't be identified as valid image files, and any
output files which already exist but are not to be
overwritten, are skipped and processing continues
with the next file.
At the end of processing Alchemy displays lists of
the files which were not found, which could not be
identified, and which already existed but could
not be overwritten.
This option was added at the request of our
customers who routinely convert large numbers of
files and don't want Alchemy to stop if it finds a
file missing or finds that an output file already
exists.
Limitations Any errors which occur during the processing of an
image file are always fatal.
This option can only be used with the Wildcard
option.
Examples Convert all the GIF files in the current directory
to JPEG files, skipping any files which can't be
identified or already have existing JPEG files:
alchemy -- *.gif -j --W
126 Image Alchemy
Wildcard --
Purpose Allow the conversion of multiple files with a
single execution of Alchemy.
Syntax -- (dash)
Comments The wildcard option allows you to specify multiple
file names and file names which include wild card
characters. Alchemy will perform the same
conversion for each input file name that it finds.
On MS-DOS systems the use of the wildcard option
(--) is not required if the first file name
specified includes a wildcard character (* or ?);
however to reduce confusion it is still
recommended.
Limitations The wildcard option (--) must be specified before
any file names.
If you are using the wildcard option you may not
specify an output file name; the file names are
automatically generated by substituting an
appropriate extension to the input file names. If
you do specify an output file name it will be
misinterpreted as another input file. An output
path name may still be specified.
Any error will terminate the execution of Alchemy;
any images which appear in the filename list after
the one causing the error will not be processed.
This includes attempting to overwrite an already
existing file without specifying the -o option.
Alchemy does not intelligently retain information
between files. For example, if you are matching a
group of files to an existing palette, the inverse
palette generation step only needs to be performed
once, but it is in fact done for each file. This
only affects the speed of conversions, not the
quality.
Examples Convert all the GIF files in the current directory
to JPEG files:
Image Alchemy 127
alchemy -- *.gif -j
Convert all the TIFF files in the directory \tiff
to PCX files in the directory \images\output:
alchemy -- \tiff\*.tif -p \images\output
Convert the files madonna.gif, bay4.gif,
everest.tga, and basil.tif to JPEG files,
overwriting any existing files:
alchemy -- -o madonna.gif bay4.gif -j
everest.tga basil.tif
Convert the files test1.tif, test2.tif, and
new*.gif to ILBM files, matching them to the
palette from the file output.pal:
alchemy -- test1.tif test2.tif new*.gif -f
output.pal -i
128 Image Alchemy
6
Colour and Palette Options
-------------------------------------------------------------------
Introduction Colour and Palette options are options which
affect the appearance of the output image. They
control such things as the number of colours in
the output image and the dithering techniques
used.
If you are currently using the Alchemy's menu
interface rather than the command-line, you can
focus on the purpose, comments, and limitations
entries in this chapter.
Image Alchemy 129
Black and White -b
Purpose Convert the image to black and white.
Syntax -b
Comments The -b and -c options used in conjunction
specifies the number of shades of gray in the
image. The default is 256 shades of gray when
converting from a true colour image. When
converting from a paletted image the number of
shades of gray defaults to the number of colours
in the original image.
The shades of gray are uniformly distributed from
0 to 255.
When converting from true colour the image will be
changed to a paletted image unless the -24 option
is used.
Related options -8 Paletted output
-24 True colour output
-c Specify number of colours
Examples Convert the file sample.jpg into a 256 shades of
gray raw file:
alchemy sample.jpg -b -r
Convert the file madonna.jpg into a 4 shades of
gray gif file called gray.gif:
alchemy -b -c4 -g madonna.gif gray.gif
130 Image Alchemy
Colours -c
Purpose Specify the number of colours for the output file.
Syntax -c colours [reserveColours]
Parameters colours
Specifies the number of colours in the output
image. May be between 2 and 256.
reserveColours
Specifies the number of colours to reserve in
the output image. May be between 0 and 255.
Comments If the input file has a larger number of colours
than specified for the output file, the image will
be quantized using Heckbert's median cut algorithm
and dithered. For further information on
Heckbert's median cut algorithm see Appendix B,
Colour and Dithering.
The number of colours to reserve is an optional
parameter. If it is present it causes the
specified number of colours to be reserved from
the beginning of the palette. The output image
will not contain any of those colour indices.
This can be useful if you have menus or other
information you wish to display at the same time
as the images and they use colours at the
beginning of the palette. The menu colours will
then not interfere with the image. The first
indices are set to black unless 16 is specified,
in which case they are set to the standard VGA
colour palette.
Limitations Specifying the number of colours only has an
effect if you are writing a paletted file (using
the -8 option) or if the output file type is
always paletted.
Converting an image with a large number of colours
to a small number of colours (less than 8) will
usually give poor results.
The reserved colours will be set to black unless
16 colours are reserved. In that case they will
be set to the standard VGA colours.
Related options -8 Convert to paletted image
-d Specify dither type
-u Use uniform palette
Image Alchemy 131
Examples Convert the image colours.gif into a 16 colour PCX
file called colour16.pcx
alchemy colours.gif -p -c16 colour16.pcx
Convert the image colours.tga into a 256 colour
GIF file called output.gif, reserving the first 16
colours.
alchemy colours.tga -g -c256 16 output.gif
132 Image Alchemy
Dither -d
Purpose Specifies the type of dithering to apply to the
image.
Syntax -d[s] ditherType [perturbation]
Parameters If the -d is immediately followed by an 's', then
a serpentine raster is used.
ditherType can be:
0:None
1:Floyd-Steinberg
2:Stucki
3:Jarvis, Judice, & Ninke
4:Stevenson and Arce
5:Sierra Lite
20:Halftone (clustered dot)
21:Bayer (dispersed dot)
22:Halftone 2 (clustered dot)
The default is Floyd-Steinberg.
perturbation
0 through 127
The default is 0.
Comments Dithering is used to reduce colour banding in an
image caused by the palette not having a perfect
match for every colour in the image.
Types 1 through 5 are all error-diffusion dithers.
Types 1 and 5 are the fastest of the diffusion
dithers, and they usually look the best on low
resolution devices like CRTs. Types 2, 3, and 4
all tend to cause an image to appear more grainy
on low resolution output devices (such as CRTs).
However, they produce better results than types 1
or 5 on high-resolution, low colour output devices
such as laser printers.
Type 20 is a digital halftone; this will produce
the most accurate grays on a laser printer, but
the image won't be as sharp as one produced by the
error-diffusion dithers. Type 21 is a dispersed
dot ordered dither; it's only advantage over the
error-diffusion algorithms is speed. Type 22 is
an additional halftone pattern. It's similar to
type 20, but with a finer screen.
Image Alchemy 133
The -d option only has an effect if the number of
colours is being reduced or the image is being re-
mapped to a new palette.
Specifying a perturbation adds noise to the image,
which can help break up visible patterns
introduced by dithering. The parameter specifies
the magnitude of the noise. Perturbation has no
effect on dither types 20, 21, and 22.
Using a serpentine raster can also help to reduce
visible patterns introduced by dithering. Using a
serpentine raster has no effect on dither types
20, 21, and 22.
Examples Convert the 256 colour file image.gif to a 16
colour PCX file using a uniform palette and no
dithering:
alchemy image.gif -p -c16 -d0 -u
Convert the true colour image sample.jpg into a
256 colour GIF file called sample.gif, using
Stucki dithering:
alchemy -g -d2 sample.jpg
Convert the 256 colour image sample.gif into a one
bit black and white PCL file called sample.pcl,
using Jarvis, Judice, and Ninke dithering, a
serpentine raster, and a little noise:
alchemy -P -b -c2 -ds3 20 sample.gif
134 Image Alchemy
EGA Palette -E
Purpose Optimize the image quality for display on an EGA
board and monitor.
Syntax -E
Comments If you are converting images to display on an EGA
board and monitor this option will optimize the
image quality.
This option reduces the palette resolution to two
bits and automatically specifies the following:
-8 -c16 -z0 2 0.
Limitations The number of colours in an EGA palette must be
less than or equal to 16; the number of colours
defaults to 16 but can be reduced by using the -c
option.
Related options -c specify number of colours
Example Convert the image dave1.tga into dave1.pcx, a PCX
file with a palette optimized for EGA use:
alchemy -E -p dave1.tga
Image Alchemy 135
False Colour -F
Purpose False colour an image using the palette from a
file. The input image will be changed to use the
palette found in the specified filename but no
attempt at picking the best match will be done.
Syntax -F filename
Parameter filename
Any valid image type which contains a palette
Comments This feature can be used to add false colour to
monochrome images. The output file is not
dithered. This is only applicable to paletted
input files.
Limitations Cannot be combined with spiff -S or match to
palette -f.
Example False colour the file scan.gif using the palette
from the file colorful.pcx, creating the GIF file
new.gif:
alchemy -F colorful.pcx -g scan.gif new.gif
136 Image Alchemy
Gamma correction -G
Purpose Specify the gamma of an input, output, or palette
file and/or perform gamma correction.
Syntax -G gammaType gammaValue
Parameters gammaType:
i:Specify input gamma
o:Specify output gamma
p:Specify gamma of palette
gammaValue:
0.0 to 4.0
Comments To perform gamma correction, Alchemy needs to know
both the input and output gamma. For some file
formats the gamma is known; if you're reading a
file with known gamma, such as JPEG, PICT,
PCPAINT, or a Targa file with the gamma field, you
don't need to specify the input gamma. Likewise,
if you're writing a file which has a fixed gamma
you don't need to specify an output gamma. Even
if reading or writing a file format which has a
known gamma you may override it by using the -Gi
or -Go option.
However, even if both input and output gamma are
known based on the input file and the output
format, you must still enable gamma correction for
any correction to take place; you can do this with
just '-G' (if you had specified input, output, or
palette gamma, this would be implied). This is
because there are quite a few images around that
have specified or implied gammas that are wrong,
which could cause Alchemy to make matters worse
instead of better.
Typical values for gamma are 1.0 for images from
Macintoshes and 2.2 for images from PCs.
Examples To convert the Mac PICT file test.pic, which has a
gamma of 1.0, to a PCX file for use on a PC (which
should have a gamma of 2.2), use:
alchemy -p -Gi1.0 -Go2.2 test.pic
Image Alchemy 137
The input gamma could have been omitted, as PICT
files have an implied gamma of 1.0, but it's best
to include it to reduce confusion.
To convert the file image.tga, which has a gamma
of 2.2, to a GIF file for use on a Mac, matching
the palette test.pal which was created with a
gamma of 1.5:
alchemy image.tga -g -Gi2.2 -Go1.0 -Gp1.5 -
ftest.pal
138 Image Alchemy
Match Palette -f
Purpose Match the output to a palette read from a file.
The input image will be re-mapped to use the
palette found in the specified file.
Syntax -f filename
Parameter filename
Any valid image type which contains a palette
Comments Using the -f option will cause the output image to
be dithered (unless you specify no dithering by
using the -d0 option).
The -f option can be useful if you are combining
several images into a collage or want to match an
image to a pre-existing palette. You can also
create a custom palette from scratch by using a
text editor and creating a .PAL file.
Limitations Cannot be combined with spiff -S or false colour -
F.
The number of colours in the final image will be
equal to the number of colours in the palette
being read in.
The specified file must contain a palette (i.e.
cannot be true colour).
Related options -l Generate palette file
-F False colour
-d Dither
Examples Convert the image bigimage.tif to a pcx file using
the palette from the file standard.pal:
alchemy bigimage.tif -p -f standard.pal
Convert the image colour.gif to a gif file called
colour2.gif using the palette from the file
newpal.gif:
alchemy -fnewpal.gif -g colour.gif colour2
Image Alchemy 139
Negate -N
Purpose Changes the image to a negative.
Syntax -N
Comments This is equivalent to a photographic negative.
When used on black and white images black is
changed to white and white is changed to black.
On colour images each of the Red, Green, and Blue
channels are inverted separately (so that bright
blue will become bright yellow).
Examples Negate the file sample.gif, generating a GIF file
called negative.gif:
alchemy sample.gif -N -g negative
140 Image Alchemy
Palette -8
Purpose Force the output image to be paletted.
Syntax -8
Comments This option is -8 because paletted images are
typically 8 bits per pixel.
Alchemy defaults to the -8 option if the input
file is paletted or gray-scale.
Some file formats require files to be paletted;
for those formats the -8 option is assumed. Some
file formats do not have a paletted variation; in
those cases the -8 option will be ignored if
specified. Some file formats only allow gray-
scale files to be 8 bit; in those cases Alchemy
will ignore the -8 option if the image being
written is not gray-scale.
The actual number of bits per pixel is determined
by the -c option (below).
If the input file is true colour the output file
will be quantized and dithered (see the -c and -d
options below).
Related options -15 True colour output
-16 True colour output
-24 True colour output
-32 True colour output
-c specify number of colours in image
-d dither
Examples Convert the JPEG file bigimage.jpg into a paletted
TIFF file with 256 colours:
alchemy -8 -t bigimage.jpg
Convert the Targa file madonna.tga to a 16 colour
PCX file (note that the -8 option is implied by
the use of the -c16 option):
alchemy -c16 -p madonna.tga
Image Alchemy 141
Palette Selection -z
Purpose Control how the palette is generated. These
options only have an effect if the palette is
being generated by Alchemy using Heckbert's median
cut algorithm.
Syntax -z sortType [selectionType [swapType] ]
Parameters Sort the image palette. SortType can be:
0:None
1:popularity
2:luminance (white to black)
3:rgb
4:luminance (black to white)
The default is None.
SelectionType can be:
0:mean
1:median
2:corner
The default is mean.
See Appendix B, Colour and Dithering, for an
explanation of these choices.
SwapType can be:
0:None
1:IBM (colour 0 is black, 7 is white)
2:Macintosh (colour 0 is white, 255 is black)
3:Sun (colour 0 is white, 1 is black)
The default is based on the file type being
written out (IBM for GIF, Macintosh for Mac PICT,
Sun for Sun Raster, and None for all others).
142 Image Alchemy
Comments The most common use for this option is to sort the
palette; in this case only a single parameter is
needed.
This option only affects palettes that are
generated by Alchemy. To sort an existing palette
you can save the image as a true colour file (such
as HSI Raw, by using the -24 -r options) and then
convert that back to a paletted file, specifying
the desired sort type. In most cases this will
not change the image (other than the palette
order); however if the palette had entries
representing colours that are nearly identical
then the image may be modified.
Limitations Note that it is not possible to specify a swapType
without first specifying both a sortType and a
selectionType. See Appendix B, Colour and
Dithering, for more information.
Example Convert the file input.tga to a gif filed called
output.gif sorting the colours by luminance, using
the mean of the Heckbert box for the colour, and
moving the colours around so that the lightest
colour is colour 0 and the darkest colour is
colour 1.
alchemy input.tga -g output.gif -z4 0 3
Image Alchemy 143
Spiff -S
Purpose Enhance the image contrast by stretching the pixel
colour values to the full 0 to 255 range.
Syntax -S spiffType
Parameter spiffType:
a:histogram stretching
b:histogram linearization
c:histogram stretching with b/w ignored
The default is histogram stretching.
Comments This command can be used if the image you are
converting is shifted in brightness or squished in
contrast. This can happen if you scan or digitize
a very dark or very bright image.
The default type, histogram stretching, simply
insures that the image has pixels which are
distributed over the entire output range (0 to
255).
Histogram linearization insures that the
distribution of pixels over the output range is
linear.
Type C spiffing is identical to histogram
stretching except that the colours absolute black
and absolute white are ignored in the image. This
is useful when you have images which have black
borders or white captions, since type A spiffing
would treat these as part of the image data and
not perform any spiffing.
Histogram linearization can produce significantly
better results than histogram stretching for some
images. Generally you will want to try both types
to see which gives better results.
Limitations The -S option cannot be used at the same time as
the -b option when converting from a true colour
image. A work around is to do the operation in
two steps, converting it to black and white first
and then spiffing the resulting image.
144 Image Alchemy
Using the spiff option at the same time as the
match palette, -f, or false colour, -F, options is
not allowed. This is because the spiff option
would be performed before the palette is changed,
which would nullify the effects. A work around is
to do the matching or false colouring first, and
then spiff the resultant image.
Related options -b Black and White
-f Match palette
-F False colour image
Example Convert the file gloomy.pcx into a PCX file called
better.pcx:
alchemy gloomy.pcx -S -p better.pcx
Do the same thing using histogram linearization
instead of histogram stretching:
alchemy gloomy.pcx -Sb -p better.pcx
Image Alchemy 145
True Colour (15 bits) -15
Purpose Force the output image to be true colour, 15 bits
(5 bits per component).
Syntax -15
Comments See the True Colour (24 bits) section, below.
Related options -8 Paletted output
-16 True colour output
-24 True colour output
-32 True colour output
Example Convert the GIF file test.gif into an
uncompressed, true colour 15 bit Targa file called
test.tga:
alchemy test.gif -a0 -15
146 Image Alchemy
True Colour (16 bits) -16
Purpose Force the output image to be true colour, 16 bits
(5 bits each for red and blue, 6 for green).
Syntax -16
Comments See the True Colour (24 bits) section, below.
Related options -8 Paletted output
-15 True colour output
-24 True colour output
-32 True colour output
Example Convert the GIF file test.gif into an
uncompressed, true colour 16 bit Targa file called
test.tga:
alchemy test.gif -a0 -16
Image Alchemy 147
True Colour (24 bits) -24
Purpose Force the output image to be true colour (not
paletted).
Syntax -24
Comments This option is -24 because true colour images are
typically 24 bits per pixel.
Some file formats require files to be true colour;
for those formats the -24 option is assumed. Some
file formats only have a paletted variation; in
those cases the -24 option will be ignored if
specified.
The file formats which may be either true colour
or paletted default to true colour if the input
file is true colour.
Certain file formats may only be paletted if the
images are gray-scale, in those cases Alchemy will
automatically switch to true colour if the output
image is colour.
Converting a paletted image to true colour will
not improve its quality or change its appearance.
The primary use of this option is to force an
image to be true colour when converting to a
format which allows either paletted or true
colour, but where the paletted variation is not
well supported (like the Targa image format).
Related options -8 Paletted output
Example Convert the GIF file test.gif into an
uncompressed, true colour Targa file called
test.tga:
alchemy test.gif -a0 -24
148 Image Alchemy
True Colour (32 bits) -32
Purpose Force the output image to be true colour, 32 bits
(8 bits per component, 8 bits for alpha).
Syntax -32
Comments See the True Colour (24 bits) section, above.
Related options -8 Paletted output
-15 True colour output
-16 True colour output
-24 True colour output
Example Convert the GIF file test.gif into an
uncompressed, true colour 32 bit Targa file called
test.tga (the alpha channel will be empty):
alchemy test.gif -a0 -32
Image Alchemy 149
Undercolour Removal -C
Purpose Control the undercolour removal process, colour
correction, and density correction for output
formats which use the CMYK colour space.
Syntax -C filename
Parameter filename
The name of the file which contains the
undercolour removal information
Comments The undercolour removal portion of the file is
compatible with the format used by Stork
Colorproofing B.V. The format of this file is
described in Appendix G, Undercolour Removal
Files.
Sample undercolour removal files can be found in
the samples directory on the Alchemy distribution
disk or tape.
Example Convert the file image.tga to an HP RTL file
called image.rtl using the undercolour removal
file sample.ucr:
alchemy image.tga --r4 -Csample.ucr
150 Image Alchemy
Uniform Palette -u
Purpose Use a Uniform Palette.
Syntax -u
Comments Instead of using the Heckbert median cut algorithm
to generate a custom palette for the image, use a
palette with entries which are evenly distributed
in the RGB colour cube.
The advantage of using a uniform palette is that
it's faster than generating a custom palette.
However, this is at the expense of image quality
since the palette isn't generated based on image
content.
When just viewing a true colour image on a
paletted display a uniform palette is used.
The -c option can be used in conjunction with -u
to specify the size of the uniform palette; in
that case Alchemy will generate a palette with not
more than the specified number of colours (but not
less than 8).
Limitations The palette size will not necessarily match the
specified size, as the actual size must be the
product of three integers. Alchemy picks integers
that roughly correspond to the sensitivity of the
human eye to red, green, and blue (30%, 59%, and
11%).
Related options -c Specify number of colours
-d Dither type
Examples Convert the file many.tga to a gif file using a
256 colour uniform palette:
alchemy many.tga -g -u
Convert the file many.tga to a gif file with up to
128 colours in a uniform palette:
alchemy many.tga -g -u -c128
Image Alchemy 151
7
Scaling Options
-------------------------------------------------------------------
Introduction These options are all related to image scaling.
Note that the -D option does not actually change
the size of the image, it specifies an aspect
ratio or image resolution to be placed in the
header of the output image.
If you are using the GUI, you can concentrate on
the comments and limitations sections, and ignore
the others.
152 Image Alchemy
Flip Image -^
Purpose Flip image vertically (turn image upside-down)
Syntax -^
Comments Causes the image to be turned upside-down.
Examples Convert the Targa file head.tga to another Targa
file called tail.tga:
alchemy head.tga tail.tga -a -^
Image Alchemy 153
Preserve Aspect Ratio -+
Purpose Preserve aspect ratio when scaling.
Syntax -+ (plus)
Comments If specified with either the -X or -Y option
Alchemy will choose the other dimension to
preserve the aspect ratio of the image.
If specified in conjunction with both -X and -Y
Alchemy will use the values specified as a
bounding box, reducing one dimension if necessary
to preserve the image aspect ratio.
Limitations Does not pay attention to the pixel aspect ratio
values in the input image.
Related options -X Scale image in horizontal dimension
-Y Scale image in vertical dimension
Examples Change the size of the image toobig.gif so that
the width is 640 and the height is the correct
number to preserve the aspect ratio of the image
(the new image will be called notbig.gif):
alchemy -X640 -+ toobig.gif -g notbig
Do the same thing but guarantee that the image
will not be larger than 640 by 480:
alchemy -X640 -Y480 -+ toobig.gif -g notbig
Do the same thing but use better quality scaling:
alchemy -Xb640 -Yb480 -+ toobig.gif -g notbig
154 Image Alchemy
Scale Image in Horizontal Direction -X
Purpose Scale the horizontal dimension of the image to the
specified number of pixels.
Syntax -X[scaleType] pixels
Parameters scaleType
The type of scaling to use:
a: nearest neighbor
b: averaging/linear interpolation
c: lanczos2
d: lanczos3
scaleType is optional; the default is nearest
neighbor. The higher the scale type the higher
the quality (and the longer the processing time).
pixels
The number of pixels in the output image in
the horizontal dimension.
Comments Nearest neighbor type scaling is faster than the
other types but introduces aliasing (which reduces
image quality). The highest quality scaling
supported is lanczos3, but it takes much longer
than averaging/linear interpolation and generally
doesn't produce significantly better results.
Limitations All of the scale types other than nearest neighbor
give much better results than nearest neighbor
scaling, but they are slower and require a new
palette to be generated for paletted output files
(you can force alchemy to use the original palette
by using the -f option and specifying the original
image as the palette file).
Related options -Y Scale in vertical dimension
-+ Preserve aspect ratio
Examples Scale the input image, test.gif, to 640 by 480
using good quality scaling, calling the output
file test2.gif:
alchemy test.gif -Xb640 -Yb480 -g test2.gif
Scale the input image, big.tga, using fast scaling
to an image which is 320 pixels across and the
same aspect ratio as the input image, calling the
output file out.tga:
alchemy big.tga -X320 -+ -a out
Image Alchemy 155
Scale the input image, oddsize.gif, using the
highest quality scaling, to an image which is no
larger than 640x480, but has the same aspect ratio
as the original image, calling the output image
new.gif:
alchemy oddsize.gif -Yd480 -Xd640 -+ new.gif
-g
Do the same thing as the previous example, but
retain the same palette:
alchemy oddsize.gif -Yd480 -Xd640 -+ new.gif
-g -f oddsize.gif
156 Image Alchemy
Scale Image in Vertical Direction -Y
Purpose Scale the vertical dimension of the image to the
specified number of pixels.
Syntax -Y[scaleType] pixels
Parameters ScaleType
The type of scaling to use:
a: nearest neighbor
b: averaging/linear interpolation
c: lanczos2
d: lanczos3
The default is nearest neighbor.
pixels
The number of pixels in the vertical
dimension.
Comments Nearest neighbor type scaling is faster than the
other types but introduces aliasing. The highest
quality scaling supported is lanczos3, but it
takes much longer than averaging/linear
interpolation and generally doesn't produce
significantly better results.
Limitations All of the scale types other than nearest neighbor
give much better results than nearest neighbor
scaling, but they are slower and require a new
palette to be generated for paletted output files
(you can force alchemy to use the original palette
by using the -f option and specifying the original
file name).
Related options -X Scale in vertical dimension
-+ Preserve aspect ratio
Examples See the -X option, Scale Image in Horizontal
Direction, for examples.
Image Alchemy 157
Specify Image Aspect Ratio -D
Purpose Specify aspect ratio for the output image.
Syntax -D aspectRatio
Parameter aspectRatio
The percentage of the width of a pixel to its
height.
Comments This option does not actually change the aspect
ratio of the image, it just adds the aspect ratio
value to the output file. This is important when
trying to export the image to software which
expects this information.
The aspect ratio of an image is the ratio of the
width of a single pixel to the height of a single
pixel. (So to specify an aspect ratio of 5:6 use
-D 83, since (5/6)*100 is 83).
Alchemy attempts to preserve the aspect ratio
value when converting images whenever one is found
in the input image, but since so few file formats
have aspect ratio information this hardly ever
happens.
To write an output image without aspect ratio
information specify an aspect ratio of 0 (zero).
This option can also be used when displaying an
image on an IBM PC.
Limitations It is not possible to specify both an aspect ratio
and a dots per inch value for an image. This is
because specifying a dots per inch value
automatically implies an aspect ratio.
Many file types do not have an aspect ratio value,
so specifying one will have no effect.
Related options -D Specify resolution
Examples You are converting a 640x350 IBM EGA PCX image
called ega.pcx (which has an aspect ratio of
35:48) to a TIFF image and you want the TIFF image
to have the correct aspect ratio value (so that an
intelligent TIFF reader will correctly interpret
the image) (Note that the value of 73 is
(35/48)*100):
158 Image Alchemy
alchemy ega.pcx -D 73 -t
The resulting image will still be 640x350, but the
TIFF file now contains the information that the
pixels are not square (and in fact are 35:48).
If you had instead wanted to convert the image to
a 640 by 480 image (with square pixels) you could
have used:
alchemy ega.pcx -Y480 -D100 -t
The -D option isn't really needed here, since any
software reading the TIFF file will assume that if
there is no aspect ratio specified the pixels are
square.
Image Alchemy 159
Specify Image Resolution -D
Purpose Specify image resolution in dots per inch for the
output image.
Syntax -D dotsPerInchX dotsPerInchY
Parameters dotsPerInchX
The resolution of the image in the X
direction in dots per inch.
dotsPerInchY
The resolution of the image in the Y
direction in dots per inch.
Comments You must specify both dotsPerInchX and
dotsPerInchY, even if they are the same.
This command does not actually change the
resolution of the image, it just adds the
resolution fields to the output image. This is
important when trying to import the image into
software which expects this information. For
example, Microsoft Word is much more likely to
give the expected results when importing a TIFF
image for printing on a laser printer if the image
has a resolution of 300 dpi.
Reasonable values to use for dotsPerInch include
72 (the resolution of a 13 inch monitor displaying
640x480) and 300 (the resolution of a laser
printer).
To write an output image without resolution
information specify a resolution of 0 0 (zero
zero).
Alchemy will preserve this information when
converting files whenever possible.
Limitations It is not possible to specify both an aspect ratio
and a dots per inch value for an image. This is
because specifying a dots per inch value
automatically implies an aspect ratio.
This option is ignored when writing a file format
which does not have image resolution.
Related options -D Specify aspect ratio
160 Image Alchemy
Example Convert the Targa file input.tga to a TIFF file
called output.tif, specifying that the resolution
of the image in the TIFF file is 300 dpi by 300
dpi:
alchemy -t input.tga -D 300 300 output
Convert the file scan.tif to a DCX variation of a
PCX file, scaling the output image to 1500 by 750
(preserving the images aspect ratio) and setting
the resolution to 200dpi by 100dpi (this is useful
if you will be faxing the image using a fax card):
alchemy scan.tif -p1 -X1500 -Y750 -+
-D 200 100
Image Alchemy 161
8
Viewing Options
MS-DOS Only
-------------------------------------------------------------------
Display Image Alchemy can display images on properly
hardware equipped MS-DOS based computers.
Depending on the hardware installed, Alchemy
supports 320x200x256, 360x480x256, 640x400x256,
640x480x256, 800x600x256, 1024x768x256,
1280x1024x256, 640x480x32768, and 800x600x32768
display resolutions.
Alchemy automatically detects which type of
display board you have installed. If there are
multiple display boards installed in one computer
then Alchemy will display images on the first
board it finds, searching in the following order:
Western Digital based 8514/A board
AI compatible 8514/A board
VESA compatible SVGA board
Other SVGA board.
Western Digital 8514/A boards which are equipped with the Western
8514/A Digital chipset are automatically recognized by
Alchemy. Depending on the model board and the
amount of memory installed, 640x480x256,
1024x768x256, and 1280x1024x256 modes are
available.
162 Image Alchemy
AI 8514/A Alchemy requires AI to be installed to use 8514/A
displays which aren't based on the Western Digital
chipset. In addition to 8514/A boards Alchemy
should also be able to display on other AI
compatible boards, such as 340x0 based boards;
however this has not been tested. For AI based
boards the only resolution available is
1024x768x256
VESA The best support for SVGA boards is available for
VESA compatible SVGA boards. VESA is a SVGA
standard which allows applications software, such
as Image Alchemy, to interrogate the SVGA board to
determine which display modes are available. Some
SVGA boards have VESA support built directly into
the BIOS found on the board; in this case Alchemy
will automatically detect the VESA driver and use
it. Other SVGA boards require a software driver
to be installed; these drivers are usually found
on the floppy disks which came with your SVGA
board (typically the driver is called VESA.EXE).
If you can't find a driver on the diskettes and
the documentation does not explicitly mention that
VESA support is built into the BIOS you might call
the manufacturer to see if a VESA driver is
available. VESA drivers are currently available
for VGA boards using chipsets from Cirrus Logic,
ATI Technologies, Chips and Technologies, Everex
Systems, Genoa Systems, Paradise Logic, Sigma
Designs, STB Systems, Tecmar, Headland Technology
(Video 7), Orchid Technology, Appian Technology,
Trident Microsystems, and Oak Technology.
Other SVGA If Alchemy cannot find a VESA SVGA board it
attempts to determine what kind of SVGA board is
present.
The 320x200x256 mode is a standard IBM VGA mode
and will work on all VGA boards. The 360x480x256
is a non-standard VGA mode which should also work
on all VGA boards.
Because of various incompatibilities between
different VGA boards, 640x400x256 and/or
640x480x256 modes are not supported on some VGA
boards. VGA boards which have been tested for the
higher resolution modes include Paradise, Tseng
Labs 3000 & 4000, Video 7, Trident, and Everex
chipset based VGA Boards.
Image Alchemy 163
General Unless you explicitly specify a resolution,
Alchemy automatically uses the lowest resolution
mode which will display the entire picture.
The image will be positioned so that its center
coincides with that of the display.
164 Image Alchemy
Offset View -_
Purpose The offset view option is used to position the
image on the screen during viewing.
Syntax -_ xOffset yOffset (dash underscore)
Parameter xOffset Number of pixels to shift the image
horizontally.
yOffset Number of pixels to shift the image
vertically.
Example
View moving the image up 100 pixels:
alchemy madonna.gif -v -_ 0 -100
View moving the image to the right 200 pixels and
down 50 pixels:
alchemy madonna.gif -v -_ 200 50
Image Alchemy 165
View Image -v
Purpose View file.
Syntax -v horizontalResolution
Parameter horizontalResolution
320:Use 320x200 mode
360:Use 360x480 mode
640:Use 640x480 mode
800:Use 800x600 mode
1024:Use 1024x768 mode
1280:Use 1280x1024 mode
Comments If displaying on a Western Digital chipset 8514/A
or VESA compatible VGA, an optional parameter may
follow the -v command. This parameter specifies
horizontal resolution and may be 320, 360, 640,
800, 1024, or 1280. The default is to use the
lowest resolution which can fit the entire image.
If the image is true colour, a uniform palette
will be used and the image will be dithered
(dithering may be disabled by use of the -d
option, see above). See Appendix B, Colour and
Dithering, for more information.
Related options -V Reduce image to fit display
Example View the image madonna.gif:
alchemy madonna.gif -v
166 Image Alchemy
View Image in True Colour Mode --v
Purpose View file using 15, 16, or 24 bits/pixel mode.
This allows true colour images to be viewed
without dithering to a uniform palette.
Syntax --v horizontalResolution
Parameter horizontalResolution
640:Use 640x480 mode
800:Use 800x600 mode
1024:Use 1024x768 mode
1280:Use 1280x1024 mode
Comments Resolutions above 640x480 are only supported by
SVGA boards with a VESA driver. 640x480 mode is
supported for various SVGA boards with sufficient
memory and the correct DAC.
Alchemy automatically picks the highest colour
resolution which will fit the image you are trying
to view. For example, if your SVGA boards
supports 800x600x15 bit and 640x480x24 bit,
Alchemy will use the 640x480x24 bit mode when
viewing images which are 640x480 and smaller and
the 800x600 mode when viewing larger images. You
can of course override this by giving Alchemy a
resolution parameter after the view command (for
example, --v 640, to view in 640x480x24 bit mode).
Example View madonna.tga:
alchemy madonna.tga --v
Image Alchemy 167
View Scaled Image -V
Purpose View image while scaling image to fit on monitor
and correcting aspect ratio.
Syntax -V horizontalResolution
Parameter horizontalResolution
320:Use 320x200 mode
360:Use 360x480 mode
640:Use 640x480 mode
800:Use 800x600 mode
1024:Use 1024x768 mode
1280:Use 1280x1024 mode
Comments This command will scale the image and correct the
aspect ratio of the image by removing rows and/or
columns from the image.
Note that this option can also be useful for
displaying images which are not larger than the
screen but which have an aspect ratio different
than the display.
Limitations Alchemy assumes that the aspect ratio of a display
pixel is 1:1 when in 640x480, 800x600, 1024x768,
and 1280x1024 modes, 5:6 when in 640x400 mode and
320x200 modes, and 16:9 in 360x480 mode.
If not otherwise specified by using the -D option
or in the file, Alchemy assumes that the aspect
ratio of pixels in 640x400 images and 320x200
images is 5:6 and the aspect ratio of pixels in
640x350 images is 35:48. You can override any of
these assumptions with the -D option.
Don't worry if this is confusing; in practice
Alchemy deals with everything automatically if you
use the -V option. However, there is a problem
with displaying 320x400 IFF files; see Appendix A,
Answers to Frequently Asked Questions, for more
information.
Related options -D Specify image resolution
-v View image
Example View madonna.gif:
alchemy madonna.gif -V
168 Image Alchemy
View Scaled Image in True Colour Mode --V
Purpose View image in 15 bit mode while scaling image to
fit on monitor and correcting aspect ratio.
Syntax --V horizontalResolution
Parameter horizontalResolution
640:Use 640x480 mode
800:Use 800x600 mode
1024:Use 1024x768 mode
1280:Use 1280x1024 mode
Comments Requires either a Tseng 4000 equipped SVGA, an S3
equipped SVGA board, or a VESA compatible SVGA
board with a Sierra DAC and 1 Megabyte of memory
on the SVGA board.
This command will scale the image and correct the
aspect ratio of the image by removing rows and/or
columns from the image.
Note that this option can also be useful for
displaying images which are not larger than the
screen but which have an aspect ratio different
than the display.
Limitations The same limitations as for scaled 8 bit viewing
apply (see page 7-7 in the User's Manual).
Related options -D Specify image resolution
--v View image in 15 bit mode
Example View sample.jpg:
alchemy sample.jpg --V
Image Alchemy 169
9
Tutorial and Examples
-------------------------------------------------------------------
Introduction This section gives a sample session of using the
command-line version of Alchemy. It is assumed
that you have installed Alchemy as instructed by
the installation section of the manual. The
sample image file, sample.jpg, which can be found
in the samples directory on the distribution disk
or tape, must be in the current directory.
Examples We will use the sample.jpg image supplied in the
\samples directory. The first step is to copy
this into the directory with Alchemy.
copy samples\sample.jpg
Now we will convert this JPEG file to a GIF file.
Notice that we don't have to specify an output
file name. Alchemy will automatically supply the
name sample.gif.
alchemy sample.jpg -g
We can then view this GIF file using Image Alchemy
(assuming you have a compatible Super VGA card):
alchemy sample.gif -v
To convert the sample.gif file to a PCX file
called test1.pcx do the following:
alchemy sample.gif test1.pcx -p
You can now view this file by doing:
alchemy test1 -v
Note here that Alchemy automatically added the
extension .pcx since none was supplied.
Let us now convert the test1.pcx file to a small
TIFF file called test1.tif, we will scale the TIFF
file to be 200x100 pixels. To perform the scaling
we will use -X and -Y options:
alchemy test1.pcx -t -Xb200 -Yb100
170 Image Alchemy
In this case we specified that Alchemy should use
type B scaling. This is a good scaling type to
use for general purpose scaling (type A scaling is
faster but not as good a quality, whereas Type C
and Type D scaling are better quality but slower).
You can now view this TIFF file by using:
alchemy test1.tif -v
If you had wanted to view it using the standard
VGA mode 320x200 you could have used:
alchemy test1.tif -v320
To convert this TIFF file to a gray-scale PCX file
use
alchemy test1.tif -b -p -o
The -b option indicates black and white and the -o
option tells Alchemy that it is okay to overwrite
the existing test1.pcx file.
You can now view this PCX file by using:
alchemy test1.pcx -v
To convert the JPEG file sample.jpg to a Targa
file called sample.tga use the following command:
alchemy -a sample.jpg
To convert the 24 bit Targa file sample.tga to a
256 colour GIF file called new.gif:
alchemy -g sample.tga new.gif
To convert the 256 colour GIF file, new.gif, to a
64 colour PCX file called new.pcx:
alchemy -p -c64 new.gif
To view the GIF file new.gif (only applicable on
IBM PCs with appropriate VGA board):
alchemy -v new.gif
Image Alchemy 171
To convert sample.jpg to a black and white, two
colour GIF file use a text editor to create a file
called BW.PAL which contains the following:
PAL
2
0 0 0
255 255 255
then:
alchemy -g sample.jpg -f bw.pal
(Alternatively, you could have said alchemy -g
sample.jpg -b -c2, but that wouldn't have
demonstrated the -f option).
To view the resulting file in 320x200x256 mode,
scaling the image to fit the display:
alchemy -V320 sample.gif
To create a LZW compressed TIFF file called
new.tif which is 320x240 from the targa file
created earlier, using good quality scaling:
alchemy sample.tga -t1 -Xb320 -+ new.tif
172 Image Alchemy
A
Answers to Frequently Asked Questions
-------------------------------------------------------------------
Question When I view a JPEG compressed image on my VGA
board it looks much worse than when I first
convert it to a GIF file and then view it. Why is
this?
Answer To save time Alchemy automatically uses a uniform
palette when you are just viewing a true colour
image. When converting to a different file format
Alchemy uses Heckbert quantization to generate a
palette. The difference in image quality is the
difference between using a uniform palette and an
optimum palette. See Appendix B, Colour and
Dithering, for more information on palette
generation.
Question Why can't my paint package read the Targa file I
wrote with Image Alchemy?
Answer Some software which reads Targa files cannot
handle compressed files. In addition, some
software can read true colour Targa files, but
cannot read paletted or gray-scale files. Image
Alchemy can be forced to write out a true colour
file by using the -24 option.
Question I told Alchemy to convert a PCX file to an 8 bit
GIF file (using the -8 option). Yet when I get
statistics on the file (using -x) Alchemy reports
the file only has 16 colours.
Answer Alchemy will always store the file using the
smallest bits-per-pixel allowable for the given
image (this results in the smallest possible
file). In this case the input file only had 16
colours in it.
Image Alchemy 173
Things get more unpredictable with formats such as
Sun Raster (which requires 1 bit files to be black
and white) and SGI (which requires 8 bit files to
be gray-scale). In these cases Alchemy will
always do the best it can (giving you a warning
message if it does something which may surprise
you later).
Question Why is decompressing or compressing a JPEG image
so slow?
Answer There are a large number of calculations that have
to be done during JPEG compression. This is an
inherent limitation of JPEG compression. Image
Alchemy has been optimized quite a bit to reduce
the number of calculations, and we are working to
further reduce the number of calculations. If you
are transferring files over modems or storing them
on slow media (tape) the compression times are
usually more than made up for by the decrease in
transmission or retrieval times.
Question Why can't my favorite desktop publishing package
read the TIFF file I wrote with Image Alchemy?
Answer Tagged Interchange File FormatTIFF is an extremely
versatile standard; it can handle anything from 1
bit images to full colour images with an alpha
channel. Also, TIFF allows many different types
of compression. Unfortunately this versatility
means that it's difficult for a single piece of
software to be able to read in every valid TIFF
file.
If the software specifies the classes of TIFF it
can read, you can force Alchemy to write out a
specific TIFF class by using the following
options:
class B: -8 -b -c2 -t2
class G: -8 -b -t1
class P: -8 -t1
class R: -24 -t1
Class B is black and white, Class G is gray-scale,
Class P is paletted, and Class R is true colour.
174 Image Alchemy
If the supported classes are not specified,
experiment with various combinations of -24, -8, -
b, and -c. In this case it is usually best to use
no compression (-t0) while experimenting with the
other options, as many TIFF readers have
difficulty with compressed files. When you find a
set of options that work, then you can try various
compression modes to save space. Be aware that
using the -b option will force the output file to
be gray-scale and you will lose the colour
information in the file (most desktop publishing
programs only have support for gray-scale TIFF
files).
You may also have to use the -Dn n option to
specify the resolution of the image (this is
especially true when converting from a file format
which does not have a value for image resolution).
You can generally tell if this is necessary
because the program you are using to read in the
TIFF file will claim that the file is unreasonably
large or small. Generally, if you are using a 300
DPI Laser Printer you want to make the TIFF file
300DPI x 300DPI (-D 300 300).
If you would like further information specific to
using Image Alchemy with your word processor or
desktop publishing program please contact us; we
will be maintaining a list of how to make Alchemy
work with other software packages. Similarly if
you figure out how to import files into a specific
package let us know and we will add your tips to
our documentation.
Image Alchemy 175
Question I've converted a Mac PICT file to a GIF file, but
the GIF file is missing some or all of the
information that was in the PICT file. What
happened to it?
Answer PICT files are a combination of drawing commands
(such as lines, rectangles, and circles) and
raster areas (called pixMaps). Alchemy can only
read the raster portions of the files. Programs
such as MacDraw and MacDraft write out files with
drawing commands, programs such as MacPaint write
out files which are entirely raster areas
(pixMaps), and some programs, such as SuperPaint
can write out files which are either, or a
combination of both. If you are using such a
program check the documentation on how to write
out files in "paint" mode.
Question When I convert a GIF file to a JPEG file and then
back to a GIF file the final GIF file is twice the
size of the original. Why is this?
Answer There are two things which might cause this to
happen:
JPEG compression doesn't really work well for
images which have large areas which are all the
same colour. The reason for this is that JPEG is
a lossy compression technique. Therefore you are
not going to get back exactly the same values for
each pixel in an area that was one solid colour
before being JPEG compressed. But GIF compression
works much better on areas which are one solid
colour, so, when you GIF compress these areas,
they are quite a bit larger than they were before.
The solution to this problem is to use HSI JPEG
compression, which automatically detects large
areas of solid colours and does not JPEG compress
them. The problem with HSI JPEG compression is
that it isn't compatible with JPEG or JFIF.
176 Image Alchemy
The other possibility is that the input GIF file
didn't have very many different colours. When you
converted it to a JPEG file the number of colours
in the file was lost (JPEG gray-scale files always
use 256 shades, and JPEG colour files are always
true colour). When the JPEG file was converted
back to a GIF file Alchemy assumed you wanted 256
colours in the file, and a 256 colour GIF file is
bigger than a 16 colour GIF file. To prevent this
you can use a -c32 (or however many colours the
original had) option in the command line; this
forces Image Alchemy to use that many colours for
the output file.
Question I keep getting "Out of Memory trying to ..."
messages. Help!
Answer Image Alchemy is running out of memory. First try
to do the conversion again with the -$ (conserve
memory) option. Next, if that doesn't help,
attempt to maximize the amount of memory available
by removing as many memory resident programs as
you can. If this still doesn't help please
contact us with the following information: your
computer configuration (amount of available
memory, size of hard disk), operating system
version, and what you are trying to do (input file
information (size of image and type of file) and
options specified). Alchemy can generally convert
images as larger than 2000 pixels wide and a
virtually unlimited number of pixels tall.
However there are certain conversions which
require more memory than others.
Question I am using Alchemy to display a 320x400 IFF image
created by an Amiga. When I use just the -v
option the image comes out tall and skinny. When
I use the -V option, which is supposed to correct
the aspect ratio, things get worse instead of
better (the image is even skinnier). What's going
on?
Answer As near as we can tell, some Amiga software has a
different idea of what aspect ratio is than the
rest of the world.
Image Alchemy 177
For displays, aspect ratio is defined as the ratio
of the width of a single pixel to the height of a
single pixel. So if you have square pixels (which
you do on a standard monitor in 640x480 mode) the
aspect ratio is 1 to 1 (commonly written as 1:1).
When you change display modes the height and width
of the total display area does not change; what is
changing is the width and height of each pixel,
which means that the aspect ratio changes. For
example, a 640x400 display has an aspect ratio of
1:1.2 (that means each pixel is 1.2 times as tall
as it is wide (which makes sense since 480/400
equals 1.2)). A 640x200 display has an aspect
ratio of 1:2.4.
Now this is where it gets interesting in terms of
IFF files. The aspect ratio number stored in
Amiga IFF files for 320x400 images is 1:1.1,
meaning pixels are 1.1 times as tall as they are
wide, so therefore the actual image should be the
equivalent size of a 320x440 image with square
pixels. And this is what Alchemy will attempt to
display when you use the -V option (Alchemy never
makes any dimension larger, so the actual image
Alchemy displays is 291x400, which is the same
ratio as 320x440). However this is obviously
wrong, as you can tell when you examine an image.
As near as we can tell the correct aspect ratio of
these images is 5:3 (the math we used to come up
with this number is 640/320:480/400). And if you
tell Alchemy to override the aspect ratio by using
a -D 167 option (167 because 5/3*100 is 166.6666)
the image displays correctly. Why Amigas create
images which claim they are 1:1.1 remains a
mystery.
178 Image Alchemy
Question When I convert a 32 bit Targa file to a GIF file
and then to a JPEG file it doesn't look nearly as
good as if I convert the Targa File directly to
the JPEG file. What can I do to maintain high
quality in JPEG compressed files?
Answer When the Targa file was converted to the GIF file
Image Alchemy had to reduce the number of colours
in the file (the original Targa File had up to 16
million colours, GIF files are limited to 256
colours). This step is known as colour
quantization (Image Alchemy uses the Heckbert
Median Cut method for quantization, see Appendix
B, Colour and Dithering, for more information).
The difficulty with colour quantization is that it
leaves artifacts known as colour banding. To
reduce this phenomenon Image Alchemy dithers the
image (you can see the effect of colour banding by
turning off dithering by using the -d0 option).
Unfortunately a dithered image does not JPEG
compress very well (dithering adds a lot of high-
frequency information to an image; JPEG
compression attempts to remove much of that
information). In addition JPEG images are always
continuous colour images, so when the JPEG file is
decompressed it has to be colour quantized and
dithered again. Dithering a previously dithered
image reduces the quality even more. The solution
is to use the best starting quality you can for
JPEG compression, ideally a continuous tone image.
The compressed image size will be smaller than if
you had started with a paletted image and the
quality will be better.
Question I've converted an HP PCL file to a GIF file, but
the GIF file is missing some or all of the
information that was in the PCL file. What
happened to it?
Answer PCL files have the same problem as PICT files (see
above); they are a combination of drawing commands
(such as lines and rectangles) and raster areas
(called rasters) and Alchemy can only convert the
raster areas in PCL files. PCL Files also contain
font and text information, which is also lost.
Unfortunately there isn't any general way to
preserve this data with Alchemy.
Image Alchemy 179
One thing which you can do if running Microsoft
Windows 3.0 is to install Adobe Type Manager
(ATM). ATM automatically intercepts any text
commands and converts them to rasters. In
addition, the standard Windows 3.0 HP PCL driver
only generates rasters, not vectors. So the file
will appear in its entirety when converted by
Alchemy. Contact us if you want further
information on using Alchemy with Windows 3.0.
Question Why can't Image Alchemy read in JPEG files
produced by Kodak's ColorSqueeze (or Sun's
VFCtool)?
Answer The JPEG standard is still in draft form. Until
it is a mature standard, various manufacturer's
will implement different versions of it. As of
March 1, 1991 Image Alchemy supports the JFIF
format and should work with any other JPEG
software which also claims JFIF compatibility. If
other software you are using claims to support the
JFIF format and you are having trouble please
contact us. If the other software does not
support JFIF, contact the manufacturer and tell
them they should send you an update which does
(you can tell them to contact us if they need a
copy of the JFIF standard).
Question I converted a PCX file with 16 colours to a 16
shades of gray TIFF file using the -b and -t
options. The 16 colour PCX file had some shades
of gray in it which were changed in the TIFF file.
How can I prevent this?
Answer The problem is that gray-scale TIFF files have a
uniformly spaced gray palette. If you create a
TIFF file with 16 shades of gray it will have the
following shades in it: 0, 17, 34, 51, 68, 85,
102, 119, 136, 153, 170, 187, 204, 221, 238, and
255. However the 16 colour PCX file you started
with probably didn't have those exact colours in
it (for example, PCX files written out by
Windows 3.0 Paint have shades of gray which
correspond to 0, 128, 192, and 255). So Alchemy
did the best it could and matched the input
colours to the output colours (and depending on
the other options that you specified may also have
dithered the image).
180 Image Alchemy
The solution is to tell Alchemy to write out a 256
colour gray-scale TIFF file (which you do by
adding a -c256 to the -b and -t options). This
file still has a uniform gray palette; but that
palette now contains every colour: 0, 1, 2, 3,
..., 255. Therefore Alchemy can map, for example,
the colours 128 and 192 to their exact match.
This does have the disadvantage of making the
resulting 256 colour TIFF file twice as large as
the 16 colour TIFF file, but this is the only way
to guarantee that Alchemy can find an exact match
for all the shades of gray in the input file.
Question Why do you only allow specifying image resolution
in Dots Per Inch? Don't you realize that most of
the world is metric?
Answer Yes, we do realize that the entire world, with the
exception of the United States and Great Britain,
claims to use the metric system exclusively (and
Great Britain will presumably change in 1992).
However, this isn't actually true. A laser
printer manufactured in Japan is still 300 dots
per inch (not 11.811... dots per mm) and a 19 inch
monitor sold in Europe is called a 19 inch monitor
(actually a 19 inch monitor is called a 20 inch
monitor in Europe, which is a measure of the total
picture tube diagonal, not just the viewing area).
Question How do I get a copy of the current draft JPEG
standard?
Answer The JPEG standard is a ISO/IEC standard currently
in Committee Draft form.
Contact your local ISO/IEC office to get a copy.
The reference numbers are ISO/IEC JTC 1 and /SC 2
N2215; the document number is ISO/IEC CD 10918-1.
In the United States you can contact ANSI at:
ANSI
11 West 42nd St.
New York, NY 10036
(212) 642-4900
Question Do you give multiple copy discounts? Do you have
site licenses? Are you interested in licensing
the source code?
Answer Yes. Yes. Yes. Contact us for more information.
Image Alchemy 181
182 Image Alchemy
B
Colour and Dithering
-------------------------------------------------------------------
Paletted vs. Colour images are normally stored in one of two
true colour ways: as an array of direct colour values (usually
red, green, and blue) (referred to as a true
colour file in this document) or as an array of
indices into a colour-map which contains red,
green, and blue colour values (referred to as a
paletted file in this document).
The reason for the existence of paletted images is
that they take less memory, so the hardware to
display them is less expensive. The dominance of
paletted hardware is changing as the price of
memory and the processing power it takes to update
large amounts of memory at a reasonable speed
drops (a Targa 32 board is an example of a true
colour board, a VGA board is an example of a
paletted board).
Until true colour graphics devices become the
norm, there is a need to convert images from true
colour to paletted. This conversion is done in
two steps: the first is to generate a palette for
use by the image; the second is to map the image
to the new palette.
Colour cube The colour model generally used by computers is a
cube with red, green, and blue as the axes (this
is known as a colour cube or RGB cube). Each
point inside the cube is a different colour,
depending on the amount of red, green, and blue
used. In nature each of the three axes is nearly
continuous, therefore there are a nearly infinite
number of colours available. Computer hardware
and software represent colours in a discrete
fashion.
Image Alchemy 183
For true colour displays or file formats the
number of discrete positions along each axis of
the colour cube gives the colour resolution of the
output device. For example, a Targa 24 board for
an IBM PC has 8 bits per red, green, and blue
channel for a total of 24 bits (or 256 discrete
shades of each colour, for a total of 16 million
colours (256x256x256)). This is also the colour
resolution of most true colour file formats.
The new 15 bit SVGA boards have 5 bits per
channel, for a total of 32x32x32 different colours
(32,768). This is the same colour resolution as a
Targa 15 file.
A paletted display or image file has the same
colour resolution limit as a true colour display
or image file, but in addition there is a limit on
how many points inside the cube can be used at the
same time. An 8 bit file format, such as GIF,
allows 256 different colours out of 16 million. A
normal SVGA board also only allows 256 different
colours at one time.
So, converting a true colour file to a paletted
file involves reducing the number of occupied
points in the colour cube. There are several ways
this can be done.
Generating a Image Alchemy supports two methods of generating a
palette palette:
Uniform The simplest and fastest method is to use a
palettes palette containing colours which are uniformly
distributed in the RGB cube, referred to as a
uniform palette. This has the advantage that it's
fast and the same palette can be used for any
image; the primary disadvantage is that most
images don't contain colours from everywhere in
the RGB cube, so palette entries are wasted
representing colours that aren't needed for the
particular image being converted.
184 Image Alchemy
Optimal To generate a palette which is better for
palettes representing a particular image, Image Alchemy
supports Heckbert's median cut algorithm. This
algorithm first builds a three dimensional table
(a histogram cube) indicating how popular any
given colour in the RGB cube is in the image being
converted. It then proceeds to subdivide this
histogram cube (by dividing boxes in half) until
it has created as many boxes as there are palette
entries. The decision as to where to divide a box
is based on the distribution of colours within the
box. This algorithm attempts to create boxes
which have approximately equal popularity in the
image.
Palette entries are then assigned to represent
each box. There are other methods of generating a
palette from an image, but Heckbert's algorithm is
generally regarded as the best tradeoff between
speed and quality.
Modifying the You can change the method used to select a colour
palette to represent each box by use of the -z options.
selection
process The default method is to use the mean of all the
colours in the box. However for some images
slightly better results can be obtained by using
the center of the box (without regard to where the
pixels are in the box).
For images being reduced to a very small number of
colours (less than 16) better results can be
obtained by using a corner of the box (the boxes
tend to be large when reducing an image to a small
number of colours; therefore picking colours near
the centers of the boxes will give you muddy
colours, while using corners of the boxes will
give you more saturated colours).
Mapping the The next step is to map the image to the new
image to the palette; this is where dithering becomes
palette important.
Image Alchemy 185
No dithering The simplest approach is to map every colour in
the original image to the palette entry which is
closest to it (this is what Image Alchemy does if
you specify no dithering).
However, since the palette entries generally
represent several different colours in the
original image, this results in colour banding
where areas of smooth colour changes in the
original become areas of one solid colour in the
paletted version.
Advantages of This can be alleviated by dithering the image data
dithering such that any given pixel might not be mapped to
its closest palette entry, but the average over
some area of the image will be closer to the
correct colour than it would otherwise be. Image
Alchemy uses a class of algorithms called "error-
diffusion" to do dithering.
Error diffusion These algorithms work by using the closest palette
dithering entry to a colour and then distributing the error
(the difference between the desired colour and the
chosen palette entry) to the nearby pixels. This
process is repeated for every pixel in the image,
using the colour values which have been modified
due to the error from previous pixels. The
different dithering algorithms spread the error
over a different area or use a different weighting
within the same area.
Serpentine Error diffusion can be done as a normal raster
raster (left to right, top to bottom) or as a serpentine
raster (alternating left to right and right to
left, top to bottom). A serpentine raster tends
to break up visible patterns introduced by
dithering.
Noise Random noise can also be added to help break up
visible patterns in the resulting image.
Further For more information on Heckbert's median cut and
information dithering see the appropriate reference listed in
the References section below.
186 Image Alchemy
C
What is JPEG Compression?
-------------------------------------------------------------------
Who are those JPEG stands for the "Joint Photographic Experts
JPEG guys? Group". This is a group of experts who defined a
standard compression scheme for still images,
commonly called JPEG Compression. Currently the
standard is still in draft form. The standard
should be finalized in 1991.
Overview JPEG Compression consists of a series of
reasonably complex mathematical operations. These
include: colour space conversion, discrete cosine
transforms, quantization, and entropy coding.
After these steps you end up with an image which
takes fewer bits to store than you started out
with.
However, when you decompress a JPEG compressed
image you end up with an image that is not quite
the same as the original (which is why JPEG
Compression is referred to as "lossy").
Is lossy You might well ask why anyone would want to
compression compress an image using a lossy technique.
bad? Compression ratios for lossy compression are much
better than for lossless compression and the loss
is generally very small. And, in fact, every
operation of converting an image is lossy (the
original photographic or electronic process which
captured the image was lossy, scanning or
digitizing the image was lossy, displaying the
image on a monitor is lossy, and printing the
image is lossy).
Details JPEG compression involves the following steps:
Image Alchemy 187
Step 1 The image is converted to a colour space with
separate luminance and chrominance channels. This
is done because the human eye is far more
sensitive to the luminance information (Y) than it
is to the chrominance information (Cb and Cr); by
separating them, it's possible to compress the
chrominance information more than the luminance
before the perceived image quality suffers.
This step isn't specified in the JPEG draft (it
doesn't discuss colour space at all), but is
standard practice. Image Alchemy uses CCIR-601
YCbCr, which is the colour space specified by the
JFIF standard.
Step 2 The luminance and chrominance information are
separately transformed to the frequency domain
using a discrete cosine transform acting on 8x8
pixel blocks.
To reduce the amount of data which needs to be
compressed the chrominance information may be sub-
sampled first. Alchemy uses 2h:1v:1h:1v:1h:1v
sub-sampling when writing JPEG files, which means
that the first component (luminance) has twice as
many samples horizontally as the other two
components (chrominance), and the same number of
samples vertically. Alchemy can read JPEG files
with any sub-sampling allowed by the draft
standard.
Step 3 quantizationThe transformed data is quantized (so
some information is thrown away). The samples
representing higher frequencies are generally
quantized using larger steps than those
representing low frequencies.
The quality level you specify is used to scale a
set of quantization values which have been found
to cause the quantized data to all have
approximately equal importance visually. A lower
quality number will cause larger quantization
steps to be used, and hence increase the
compression ratio and decrease the image quality.
188 Image Alchemy
Step 4 The quantized data is compressed using an entropy
coder. Huffman and Arithmetic coding are allowed
by the draft JPEG standard; only Huffman coding is
allowed by the JFIF standard. Huffman coding can
either be done with a set of fixed tables or
custom tables can be generated for an image.
Alchemy, by default, uses a fixed set of tables,
but can also generate custom tables which usually
produce 5-20% (depending on the image and quality
setting) better compression. However, producing
custom tables requires an additional pass over the
image data and therefore takes a little longer.
Alchemy can write JPEG files using either Huffman
or arithmetic coding; arithmetic coding generally
results in a slightly smaller file, but at the
cost of non-JFIF compatibility and longer
compression and decompression times.
JPEG This data corresponds to the JPEG Interchange
Interchange Format and is ready to be stored in a file.
Format Unfortunately the JPEG Interchange Format does not
include enough information to actually be able to
convert the file back to an image. Specifically
the colour space used and the aspect ratio or
resolution of the image are not included. Until
recently there was no standard way of putting this
information in a JPEG file.
JFIF On March 1, 1991 representatives of several JPEG
hardware and software developers (including C-
Cube, Radius, NeXT, Storm Tech., the PD JPEG
group, Sun, and Handmade Software) met at C-Cube
and established the JPEG File Interchange Format
(JFIF). If you would like more information on the
JFIF standard please contact us.
Image Alchemy 189
D
Customer Support
-------------------------------------------------------------------
Why might We have made every effort to insure that Image
Alchemy mess Alchemy can read all files in its supported
up? formats. However, because of poorly written
standards and non-adherence to standards there are
undoubtedly certain files that Image Alchemy does
not read correctly.
What we need to If you come across any files which Image Alchemy
help you has trouble with please contact us with as much of
the following information as you have: version of
Image Alchemy you are using, type of file, type of
computer which generated it, name and version of
software which wrote the file, size of image, and
the number of colours in image. We may ask you to
send us the file so that we can figure out what
went wrong. If you send us a file we will attempt
to modify Image Alchemy so that it can read the
file. Once Image Alchemy is modified, we will
send you an updated copy of Image Alchemy.
Similarly, if any files that Image Alchemy writes
cannot be read by other software please contact
us. We may ask you to send us a copy of a file
that can be read by that software package for
comparison.
Please contact us even if you are just using a
demo copy of Alchemy. In addition to helping fix
a potential bug, we feel the best way to get you
to purchase a copy of Alchemy is to demonstrate
how committed we are to customer support.
190 Image Alchemy
How to contact Our address and phone numbers are:
us
Handmade Software, Inc.
15951 Los Gatos Blvd., Suite 17
Los Gatos, CA 95032
+1 800 358 3588 (Toll-free from the U.S.)
+1 408 358 1292 (Voice)
+1 408 358 2694 (Fax)
The most efficient way to contact us is by e-mail;
this is especially true if you can send us a
sample file which demonstrates the problem. Our
e-mail addresses are:
Internet: [email protected]
CompuServe: 71330, 3136
We also have a 24 hour bulletin board BBS where
you can upload and download files. It speaks 2400
baud, 9600 baud (v32, v42, and v42.bis), and PEP
and its number is:
+1 408 356-3297 (BBS)
Image Alchemy 191
E
Binary Information Files (BIF)
-------------------------------------------------------------------
Overview Binary files are image files which are just data.
In other words, they do not contain any
information other than the actual pixels in the
image. In order to read these files you must
create a file using a text editor which describes
to Alchemy the format of the file you are trying
to read in. This is called a BIF file (and
normally has the extension .bif).
Required At the minimum a BIF file needs to contain the
information filename of the image file and either the height
or the width of the image. Alchemy will make
assumptions about the other characteristics of the
image based on the information that it is given
and the total length of the image file.
BIF file format The first line contains the letters BIF, which
identifies the file as a BIF file.
Each of the rest of the lines in the BIF file
consist of an information tag followed by the
information. The spelling of the tags must be
exact or Alchemy will report an unknown tag error.
192 Image Alchemy
Tags
Tag Description
filename The name of the file containing the binary data.
width The width of the image data, in pixels.
height The height of the image data, in pixels.
planes The number of planes of image data (1, 2, 3, or
4).
A 1 plane image is assumed to be gray-scale, a 2
plane image is a gray-scale image with an alpha
channel, a 3 plane image is a RGB image, and a 4
plane image is a RGB image with an alpha channel.
header The size of the header, in bytes. This many bytes
will be skipped when reading the file.
leftpadding The number of bytes to remove from the beginning
of each scan line.
rightpadding The number of bytes to remove from the end of each
scan line.
order The order of the pixels.
For 3 channel images, this can be any sequence of
r, g, and b: rgb, rbg, grb, gbr, brg, or bgr
(r=red, g=green, b=blue).
For 4 channel images, this can be any sequence of
a, r, g, and b (a=alpha).
Either ga or ag for 2 channel images (g=gray,
a=alpha).
The defaults are g, ga, rgb, and rgba, depending
on the number of planes.
upsidedown The presence of this tag indicates that the data
in the file is recorded from the bottom of the
screen up to the top of the screen.
Comments Lines beginning with a # are treated as comments.
Comments and blank lines are ignored when
processing the file.
Image Alchemy 193
Palette files If the binary file has a palette available, you
can use that palette by writing custom software to
convert it to a .PAL file and using the -F option
while reading the BIF file.
Example This is an example BIF file which can be used to
read a 640 pixel wide, true colour HSI Raw file.
Note that HSI raw files have a 32 byte header
which is being skipped. Of course you could read
the Raw file directly using Alchemy, but this is
after all an example of a BIF file.
BIF
width 640
#skip past header
header 32
filename sample.raw
planes 3
#the tag below isn't actually needed,
#since rgb is the default, but is
#included here to give an example of
#what an order tag looks like
order rgb
Using the Assuming the BIF file is called sample.bif, the
example BIF following Alchemy command can be used to convert
file the image to a GIF file:
alchemy sample.bif -g
The height of the image will be automatically
calculated from the length of the file and the
width, header, and planes tags.
A BIF file is treated as an ordinary file, so all
the standard Alchemy commands may be used.
194 Image Alchemy
F
HSI Raw Files
-------------------------------------------------------------------
History The HSI Raw format was originally intended as an
internal format to Image Alchemy. Because of user
demand the format has been documented to allow
others to read and write HSI Raw files.
Overview HSI Raw files are completely uncompressed,
unpacked, and unpadded image data files.
Therefore they tend to be larger than almost any
compressed file format. However, they have the
advantage, as far as Alchemy is concerned, that
they are very fast to read and write and the
location of any pixel in the image may be found by
simple calculations.
If you need to convert custom files to a format
that Alchemy can read we recommend using a Raw
file; it is the simplest format to write and the
fastest for Alchemy to read.
Variations There are two types of HSI Raw Files: paletted
and true colour. Paletted images are stored one
byte per pixel with a palette at the beginning of
the file. True colour files are stored three
bytes per pixel.
Gray-scale Gray scale files are stored as paletted files with
a palette that contains all gray values. Alchemy
automatically recognizes such files during reading
and will treat them appropriately.
Black and white Black and White files are stored as paletted files
with a palette that contains two values, black and
white. Alchemy automatically recognizes such
files during reading and will treat them
appropriately.
Warning Note that Handmade Software, Inc. reserves the
right to make changes to this format at any time
and without notice. And while it is unlikely, it
is possible that future versions of Image Alchemy
will not support this format.
Image Alchemy 195
Old version This appendix describes version 4 Raw files. This
files is the version that Image Alchemy has written
since March 1991. Before this Alchemy wrote
version 2 and 3 raw files (version 2 were 8 bit
files, version 3 were 24 bit files). Those raw
files can be read by current versions of Image
Alchemy but are not otherwise supported. If you
run across any of these raw files the easiest
thing to do is to use a current copy of Alchemy to
convert them to a version 4 raw file.
Details
Word size All values which are not otherwise identified are
two byte integers (16 bits). This is the native
integer size of most IBM PC C-compilers but not
for Macintosh and Sun C-compilers.
Byte order All integers are stored high byte first (big-
endian order). This is the native mode for
Macintosh's and Sun's but not the native mode for
IBM PC's.
See below for a CPU independent method to read and
write 2-byte integers.
Pixel format Paletted files are stored one byte per pixel.
True colour files are stored as three bytes per
pixel in red, green, blue order.
Padding Neither the palette information nor the pixel data
is padded to anything other than a byte boundary.
This means that if you store a file which is 13 by
11 pixels it will occupy 429 bytes if stored as a
true colour file (not including the header), or
143 bytes if stored as a paletted file (not
including the header and palette data).
Hex Numbers including a 0x prefix are hex; all other
numbers are decimal.
File format The header for a paletted file is 32 bytes plus
the size of the palette. The header for a true
colour file is exactly 32 bytes (a true colour
file contains no palette).
196 Image Alchemy
Magic number Six bytes used to identify the file as a HSI Raw
file:
0x6d 0x68 0x77 0x61 0x6e 0x68
Version An integer used to identify the version HSI file:
0x0004
Width An integer indicating the width of the image (in
pixels).
Height An integer indicating the height of the image (in
pixels).
Palette size An integer indicating the number of entries in the
palette. Range is 2 to 256. A 0 or -24
indicates a true colour image (which has no
palette data).
Horizontal DPI An integer indicating the horizontal resolution of
the image, in dots per inch. A zero indicates
that the resolution is unknown. A negative number
is used if only the aspect ratio is known.
Vertical DPI An integer indicating the vertical resolution of
the image, in dots per inch. A zero indicates
that the resolution is unknown. A negative number
is used if only the aspect ratio is known.
Gamma An integer indicating the gamma of the image,
scaled by 100 (a gamma of 2.2 is stored as 220).
A zero indicates that the gamma is not known.
Reserved Twelve bytes reserved for future use. Should be
set to zero when writing.
Palette The palette data is stored as 3 bytes per palette
entry. The bytes are in red, green, blue order; 0
is black, 0xff is full intensity.
True colour raw files have no palette.
Image data The image data.
Example files
Image Alchemy 197
8 bit paletted, 6D 68 77 61 6E 68 00 04 01 40 00 C8 01 00 00 00
320 x 200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
49 24 24 24 00 00 00 00 00 DB 6D 6D FF 92 92 FF
B6 B6 92 49 49 FF DB DB FF B6 92 FF FF DB FF DB
B6 FF FF FF B6 6D 6D 6D 24 24 DB 92 6D 6D 49 49
...
24 bit true 6D 68 77 61 6E 68 00 04 01 40 00 C8 00 00 00 00
colour, 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
320 x 200: 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24 49
24 24 49 24 24 49 24 24 49 24 24 49 24 24 49 24
24 49 24 24 49 24 24 49 24 24 49 24 24 49 24 24
...
Reading a two
byte integer
int getWord(int i, FILE *stream) {
register int temp;
temp=getc(stream)<<8;
return(getc(stream) | temp);
}
Writing a two
byte integer
int putWord(int i, FILE *stream) {
putc(i>>8, stream);
return(putc(i&0xff, stream));
}
198 Image Alchemy
G
Undercolour Removal Files
-------------------------------------------------------------------
Summary Undercolour removal files are text files which
control the conversion from RGB to CMYK colour
space.
This conversion consists of four steps. The first
is to convert an RGB value to an ideal CMY value;
this simply involves negating the RGB values. The
next step is to determine how much black is in
that colour; this is done by finding the minimum
of the CMY values and using that as an index into
the black removal tables documented below. These
tables have independent values for how much black
to use for that pixel and how much black to
subtract from the CMY values. Next, a linear
transform is optionally applied to the CMY portion
of the CMYK pixel. Finally the CMYK values are
optionally translated, independently, through the
CMYK density correction tables (this last step is
only used if Alchemy is going to dither the image
for output on a 1 bit per pixel per component
device).
File format Any line beginning with ';' is a comment and is
ignored.
Black removal The first 256 non-comment lines contain
tables undercolour removal values corresponding to
computed black values of 0 (white) to 255 (black).
Each of these lines has two numbers; the first
indicates how much black to use in place of the
computed black value corresponding to the line,
and the second indicates how much black to
subtract from the cyan, magenta, and yellow
components (this value must not be greater than
the corresponding computed black value).
After the black removal block the remaining blocks
may appear in any order.
Image Alchemy 199
CMY linear If there is a line which says only "HSI CMY
transform matrix" then the next 3 non-comment lines contain
a matrix representing a linear transform which is
applied to the cyan, magenta, and yellow
components after black removal and before applying
the density map. The entries are normalized
around 256. The first row and column represent
cyan, the second magenta, and the third yellow.
The rows are multiplied by the input cyan,
magenta, and yellow values to create the corrected
values. A matrix of
256 0 0
0 256 0
0 0 256
is equivalent to omitting the matrix and causes no
correction to take place. In this case it would
be preferable to omit the matrix as the conversion
will run slightly faster without it.
CMYK density If there is a line which says only "HSI CMYK
correction density map" then the next 256 non-comment lines
tables contain density correction tables, corresponding
to cyan, magenta, yellow, and black values of 0
(white) to 255. Each of these lines has four
numbers representing, in order, the amount of
cyan, magenta, yellow, and black to use in place
of the corresponding computed values. These
tables are only applied during dithering; they
will not be used for those CMYK output formats
which are continuous tone, as devices which take
continuous tone input data should be doing their
own correction.
Example The following undercolour removal file has
undercolour removal tables, CMYK density
correction tables, and a CMY colour correction
matrix.
; Undercolour removal file
;
0 0
1 1
1 1
2 2
3 3
... (256 entries total)
169 169
200 Image Alchemy
169 169
170 170
;
HSI CMY matrix
;the following matrix leaves the
; Cyan and Yellow planes alone, and
; subtracts a bit from the Magenta
; plane when there's Cyan present.
;
256 0 0
-32 256 0
0 0 256
;
HSI CMYK density map
;
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
... (256 entries total)
246 246 246 246
248 248 248 248
251 251 251 251
253 253 253 253
255 255 255 255
Image Alchemy 201
H
PAL Files
-------------------------------------------------------------------
Overview PAL files are text files which contain a palette
in an ASCII form. Alchemy can extract palettes
from other file formats and write PAL files.
Alchemy can also use PAL files when converting
images.
File format The first line contains the letters "PAL"; this
identifies the file as a palette file.
The next line contains an integer indicating the
number of palette entries. Valid values are 2
through 256.
The rest of the file consists of lines of 3
numbers each (separated by spaces) representing
the red, green, and blue values for each of the
colours. These have a range of 0 (black) to 255
(full intensity).
Example
PAL
8 ;# colours
0 0 0 ;black
255 0 0 ;bright red
0 128 0 ;dark green
255 255 0 ;yellow
0 0 255 ;blue
255 0 255 ;magenta
63 63 63 ;gray
255 255 255 ;white
202 Image Alchemy
I
Acknowledgments
-------------------------------------------------------------------
Summary Almost all the software which comprises Image
Alchemy was written in house. However the TIFF
and 640x400 SVGA display modules are modifications
of software originally written by other people.
Both of these modules are free for anyone's use as
long as proper credit is given as to the origin of
the software.
TIFF Image Alchemy's TIFF I/O is based on libtiff which
is copyright by Sam Leffler and is used with his
permission. If you are interested in reading or
writing TIFF files we strongly suggest that you
start with libtiff.
Libtiff is available by anonymous ftp as
ucbvax.berkeley.edu:pub/tiff/*.tar.Z or
uunet.uu.net:graphics/tiff.tar.Z.
If you cannot get a copy of libtiff via anonymous
ftp please contact us for a free copy.
VGA display Image Alchemy's 640x400 SVGA display routines are
based on VGAKIT, written by John Bridges.
VGAKIT is available free of charge from a variety
of bulletin boards
If you cannot find VGAKIT locally please contact
us for a free copy.
Image Alchemy 203
J
Other Useful Software
-------------------------------------------------------------------
Summary There are several image processing packages
available for little or no cost.
Please be aware that we mention these software
packages only as a service to Image Alchemy users.
We are not endorsing or recommending any
particular package. Many of the packages are not
supported by their authors.
If you have trouble finding any of the listed
software please send us a blank tape or diskette
and we will send you a copy free of charge (please
be aware that the software may be quite large;
contact us first if you have any questions).
If you know of any other software which would be
appropriate to add to this list please let us
know.
If you are the author of any of these packages and
you would rather not be on this list please let us
know.
204 Image Alchemy
IBM PC
PicLab A public-domain image file conversion and printing
tool.
Written by Lee Crocker and the Stone Soup Group.
Available via CompuServe.
Cshow A shareware image viewing program.
Written by Bob Berry.
Available from:
Canyon State Systems and Software
PO Box 86
Sedona, AZ 86336
Vivid A shareware ray-tracing program.
Written by Stephen B. Coy
Available from:
Stephen Coy
15205 NE 13th Pl., #2904
Bellevue, WA 98007
Workstations These programs are only available as source code
and generally require a workstation running UNIX
or one of its variants.
Utah Raster Written by Spencer W. Thomas, Rod G. Bogart, and
Toolkit (URT) James Painter.
Available via anonymous FTP as pub/urt-3.0.tar.Z
via anonymous ftp from cs.utah.edu,
weedeater.math.yale.edu, or
freebie.engin.umich.edu.
Fuzzy Bitmap Written by Michael Mauldin
Manipulation Available by anonymous ftp as
(FBM) nl.cs.cmu.edu:/usr/mlm/ftp/fbm.tar.Z,
uunet.uu.net:pub/fbm.tar.Z, or
ucsd.edu:graphics/fbm.tar.Z.
Portable BitMap Written by Jef Poskanzer
(PBMPLUS) Available by anonymous ftp as
expo.lcs.mit.edu:contrib/pbmplus.tar.Z or
ftp.ee.lbl.gov:pbmplus.tar.Z.
Image Alchemy 205
Img Software Written by Paul Raveling
Set Available by anonymous ftp as
expo.lcs.mit.edu:contrib/img_1.3.tar.Z or
venera.isi.edu:pub/img_1.3.tar.Z.
206 Image Alchemy
Glossary
-------------------------------------------------------------------
Anonymous FTP An easy way to transfer files via the Internet.
If you don't have Internet access you can't use
anonymous FTP; if you do have Internet access you
probably already know about it (if you don't, ask
your system administrator or local network guru).
Black and white An image which contains just two colours, black
and white. Many file formats, such as TIFF and
Sun Raster, have special variations for black and
white images. You can force Alchemy to write a
black and white image by specifying -b -c2 as
options.
Dithering A technique for reducing the amount of colour
banding in an image when converting from a large
number of different colours to a small number of
different colours. Different dithering techniques
are usually named after the person or persons who
first invented them. Alchemy supports Floyd-
Steinberg, Stucki, and JJN dithering; these are
further described in "Digital Halftoning", by
Robert Ulichney, MIT Press.
Gray-scale An image which contains just shades of gray. Many
file formats, such as TIFF and Silicon Graphics,
have special variations for gray-scale images.
You can force Alchemy to write a gray-scale image
by specifying -b -8 as options.
Header The portion of an image file that is not the
actual image data. The data in a header generally
includes the image size (in pixels), the image
depth (in number of bits per pixel or number of
colours), and the palette (if the image has a
palette). Some file formats include quite a bit
of additional data in the header, such as: the
name of the image, the date and time the image was
created, and the latitude and longitude of the
image (primarily used by satellite image data).
The header is called the header because it usually
appears at the head of the file. Some file
formats store information which is usually found
in the header in a separate file.
Image Alchemy 207
Heckbert colour A technique for reducing the number of colours
quantization needed by an image, typically used to convert a
true colour image to a paletted image. Named
after Paul Heckbert who originally described the
technique in "Color Image Quantization for Frame
Buffer Display", SIGGRAPH '82 Proceedings, p. 297.
Magic Number A number or sequence of numbers that is found at
or near the start of an image file so that
software may determine what type of format the
file is. Most formats have a well defined magic
number; some formats do not, in which case Alchemy
examines various parameters in the header of the
file and guesses what format the image is.
Paletted An image which isn't true colour. Each pixel in
the image is an index into a table of values
(typically red, green, and blue) which describe
the colour of that pixel. Most paletted images
are limited to 8 bits of information, which allows
256 unique colours. Most display adapters only
allow the display of paletted images (Alchemy can
display true colour images on those display
adapters by using a uniform palette).
True colour An image which does not contain a palette. Each
pixel in the image is represented by at least
three values, typically red, green, and blue.
True colour images are generally produced by
scanners and digitizers and are better quality and
much larger than paletted images. Most display
systems cannot display true colour images.
208 Image Alchemy
References
-------------------------------------------------------------------
General Computer Graphics - Principles and Practice,
Computer Second Edition
Graphics (Commonly referred to as Foley and van Dam)
J.D. Foley, A. van Dam, S.K. Feiner, and J.F.
Hughes
Addison-Wesley
ISBN 0-201-12110-7
Principles of Interactive Computer Graphics
(Commonly referred to as Newman and Sproull)
W.M. Newman and R.F. Sproull
McGraw-Hill
ISBN 0-07-046338-7
Algorithms for Graphics and Image Processing
Theo Pavlidis
Computer Science Press
ISBN 0-914894-65-X
Graphics Gems
Andrew S. Glassner
Academic Press
ISBN 0-12-286165-5
Graphics Gems II
James Arvo
Academic Press
ISBN 0-12-064480-0
Bit-Mapped Graphics
Steve Rimmer
Windcrest
ISBN 0-8306-3558-0
Image Alchemy 209
Specific Topics
Colour The Reproduction of Colour in Photography,
Printing & Television
R.W.G. Hunt
Fountain Press
ISBN 0 85242 356 X
Dithering Digital Halftoning
Robert Ulichney
MIT Press.
ISBN 0-262-21009-6
Image Scaling Digital Image Warping
George Wolberg
IEEE Computer Society Press Monograph
ISBN 0-8186-8944-7
VGA Programming Programmer's Guide to the EGA and VGA Cards,
Second Edition
Richard F. Ferraro
Addison-Wesley
ISBN 0-201-57025-4
210 Image Alchemy
Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!
This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/