GIFPRT User's Guide Page 1














GIFPRT User's Guide
Version 5.1
Copyright (c) 1992 Edward B. Hamrick
All Rights Reserved


























Please send all suggestions, error reports, and corrections to:

Compuserve: 71470,3236
Internet: [email protected]











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TRADEMARKS

GIF, Graphics Interchange Format, and Compuserve are trademarks of
Compuserve, Inc., an H&R Block Company.

IBM and PC-DOS are registered trademarks of International Business
Machines Corporation. IBM PC, XT, and AT are trademarks of
International Business Machines Corporation.

Microsoft and MS-DOS are registered trademarks of Microsoft
Corporation.

Hercules is a trademark of Hercules Computer Technology.

Epson is a trademark of Epson America.




ACKNOWLEDGEMENTS

GIFPRT was written entirely using Borland C Version 3.0.

The User's Guide was created using Microsoft Works.






























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1.0 Introduction

GIFPRT (jiff-print) is a program that lets you display and
print graphics files that use the Graphics Interchange Format,
commonly known as GIF files. GIFPRT will let you print using
almost any type of printer, including those that support Epson
and IBM 8-pin and 24-pin graphics, Epson-compatible color
printers, Hewlett Packard Laser printer graphics, and
Toshiba/Qume 24-pin graphics, and the Hewlett Packard DeskJet
500C color printer. GIFPRT can also be used to display any GIF
file on almost any type of graphics adapter, including Hercules,
CGA, EGA, MCGA, VGA, and Super-VGA adapters.

Most graphics devices are capable of only displaying a few
colors or shades of gray, and dot-matrix printers are only
capable of displaying an array of black (or sometimes colored)
dots. However, many GIF files contain images with up to 256
different colors. GIFPRT uses an error-dispersion algorithm
(also called a dithering or half-toning algorithm) to try to
display the image in the GIF file. This error dispersion
algorithm takes advantage of the number of colors that an adapter
can display to approximate the colors in the GIF file. If you
have a CGA or Hercules adapter, GIFPRT will display images with a
pattern of black and white dots. If you have an EGA adapter,
GIFPRT will display images in either an 8-color dithered pattern,
or a 2-level dithered gray scale. If you have a VGA adapter,
GIFPRT can use the 256 color display capability and display
images without any need for dithering.

There are a many different printer and adapter resolutions.
For instance, some printers can display 60, 120, or 180 dots per
inch, in either the horizontal or vertical direction. Other
printers display 72, 144, and 216 dots per inch, and yet others
display combinations of 60 and 72 dots per inch in both
directions. Display resolutions can vary from 320 by 200 dots,
to 1280 by 1024 dots, with a dozen resolutions between. GIF
files can contain images with an equally wide range of
resolutions. The GIFPRT program contains a sophisticated
resolution-matching algorithm to display almost any GIF file in a
way that makes it as large as possible on the screen or printer
without distorting the image in either direction.

Because of the wide variety of Super-VGA graphics adapters,
it is difficult for one program to support them all. However, a
standard for Super-VGA graphics drivers has been published by the
Video Electronics Standards Association (VESA) for writing
programs that use Super-VGA graphics adapters. To take advantage
of the VESA Super-VGA graphics modes, you need to obtain a VESA
"BIOS Extender" program. These are available for almost every
type of Super-VGA graphics adapter on Compuserve.







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Even though GIFPRT handles the most popular printer types,
you may find that your particular printer doesn't print exactly
the way you'd like. It is possible to customize GIFPRT to handle
almost any type printer, or to change the placement or size of
the image on the page (see section 4.0).

2.0 Prerequisites

This section describes the hardware and software needed to
run GIFPRT, and the procedure for registering GIFPRT.

2.1 Hardware Required

In order to use GIFPRT, you will need an IBM PC, XT, AT, or
other compatible personal computer with a minimum of 384K of
memory. GIFPRT will run at any hardware clock speed, including
4.77 MHz, and can be loaded from either a floppy disk or a hard
disk. GIFPRT will display GIF images on almost any display
adapter, and on most Epson, IBM, and HP compatible printers.

If your printer is connected to a port other than LPT1,
LPT2, or LPT3, you will need to use the DOS MODE command to
direct LPT1 to the proper port.

2.2 Software Required

In order to run GIFPRT, you will need a copy of MS-DOS or
PC-DOS, version 2.1 or higher. You also need the following
GIFPRT files:

GIFPRT.EXE Main GIFPRT program
GIFPRT.PR0 Epson 8-pin 120x72 dpi print commands
GIFPRT.PR1 Epson 8-pin 120x60 dpi print commands
GIFPRT.PR2 IBM 8-pin 120x72 dpi print commands
GIFPRT.PR3 IBM 8-pin 120x60 dpi print commands
GIFPRT.PR4 Epson 24-pin 240x216 dpi print commands
GIFPRT.PR5 HP Generic 75x75 dpi print commands
GIFPRT.PR6 HP Generic 300x300 dpi print commands
GIFPRT.PR7 HP Deskjet 500C 300x300 dpi print commands
GIFPRT.PR8 Toshiba 24-pin 180x180 dpi print commands
GIFPRT.MAP Compuserve Weather Map Color Map Data
GIFPRT.DOC GIFPRT User's Guide

If you have a Super-VGA graphics adapter, you'll need to get
the VESA BIOS Extension program for your particular adapter, and
load it prior to running GIFPRT.











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GIFPRT is capable of using Expanded (EMS) memory for working
with GIF files larger than those that will fit into your main
memory. To use this feature, you'll have to load the EMS driver
prior to running GIFPRT. If you don't have EMS, but you do have
a system with a 386 processor, you can load the EMM386 driver to
simulate EMS with the Extended memory in your system. If you
don't have any EMS memory, GIFPRT will use a temporary file in
the current disk directory to temporarily store image data that
won't fit in your memory.

2.3 Registering GIFPRT

GIFPRT is distributed via Compuserve as shareware, and may
be evaluated for 14 days without charge. If you decide you want
to register GIFPRT, please send $25.00 (other currencies
accepted) to:

Ed Hamrick or Ed Hamrick
Am Salzpfad 51 c/o Phil McGuigan
6382 Friedrichsdorf 21608 121st Place SE
Germany Kent, WA 98031

3.0 Running GIFPRT

To run GIFPRT, type the following command at a DOS prompt:

GIFPRT [options] [files]

For example, the command C> GIFPRT -P0 MONALISA.GIF
will print the file MONALISA.GIF on an Epson-compatible printer.

You can get on-line help by pressing the "H" key, the F10
function key, or the control-F10 function key while running
GIFPRT. You can get the same help screens by typing:

GIFPRT -H Gives list of command-line and interactive options

GIFPRT -G? Gives list of display modes

GIFPRT -P? Gives list of printer types

If you want to terminate GIFPRT, press the escape key once
if you are in interactive mode, or twice if you are displaying an
image. You can always terminate any long-running function (such
as printing a GIF file) by pressing any key.

GIFPRT chooses whether to use color (white on blue) or black
and white for it's interactive screens based on the starting
display mode. If you want color screens, type "MODE CO80" before
starting GIFPRT. If you want black and white screens, type "MODE
BW80" or "MODE MONO" before starting GIFPRT.






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If you begin GIFPRT without specifying any files, all files
in the current directory with the ".GIF" extension will be
displayed on an interactive file display screen. You can select
a different file by using the arrows, space bar, backspace key,
PageUp, PageDown, Home, and End keys to change the active file.
You can also use any other interactive option described below.
The last line of the display shows the current settings of the
various options.

When you want to display or print the currently selected
file, press the Enter key. The type of display or printout that
will be done is displayed in the lower right-hand corner of the
screen. To change the display mode, press any one of the
function keys F1 through F8. To change the printer type, press
control-F1 through control-F9. To set up a black/white display
or printout, press the 1 key. To set up an 8-color display or
printout, press the 2 key. Press the 3 key for a 256 color
display (not possible for printers). While a file is being
displayed, you may press any key that you could press while in
interactive mode. To return to the interactive file display
screen, press the Escape key. To exit the program, press the
Escape key once more.

3.1 Brightness (-Bn or function keys B,+,-)

You can use the brightness option to increase or decrease
the intensity of a GIF file. This is sometimes useful when
printing on 24-pin printers, when the image is too dark, or when
you want to avoid wearing out the print ribbon. The normal
brightness option is 5, the brightest setting is 9, and the
darkest is 1. A brightness of 9 increases the minimum intensity
to 80% of the maximum, and a brightness of 1 decreases the
maximum intensity to 20% of the minimum. A brightness of 5 does
not alter the image.

3.2 Contrast (-Cn or function keys C,/,*)

You can use the contrast option to change the contrast in an
image. This is primarily useful for adjusting for dot overlap on
printed images. Normal contrast is 5, and contrast values can go
from 1 to 9.

3.3 Dithering Flag (-D or function key D)

The dithering option can be used to disable dithering, and
to display the closest available colors. This option allows
quicker viewing of GIF files, and sometimes produces better
looking images of cartoon-like GIF files. It is toggled on and
off each time it is used.








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3.4 File Output Type (-Fn or function key F)

The file output type option allows you to select line
printer ports or files for the print output:

-F1 LPT1
-F2 LPT2
-F3 LPT3
-F4 GIFPRT.OUT (binary, suitable for printing)
-F5 GIFPRT.OUT (formatted ASCII)

3.5 Graphics Type (-Gn or function keys G,F1-F8,1,2,3)

You can use the graphics type option to select the type of
graphics adapter and display mode. You can get a list of
supported graphics options by typing GIFPRT -G?, or typing F10 in
interactive mode. Function keys F1 through F8 change the
graphics mode from lowest to highest resolution while in
interactive mode. The number keys 1, 2, and 3 change to 2-color,
8-color, and 256-color mode, respectively.

The current display mode is displayed in the lower-right
hand corner of the screen in interactive mode.

3.6 Help Screen Display (-H or function key H)

The help screen display option displays a help screen with a
summary of all command-line options and function keys.

3.7 Jet (DJ500C) Color (-J or function key J)

The jet (HP DeskJet) option adjusts the colors in the
display to be better matched to the inks used by the Hewlett
Packard DeskJet 500C printer. It reduces the amount of Cyan in
the display by 2/3 for shades of gray (unsaturated colors), and
proportionally less for less saturated colors. This reduces the
Cyan tint of the image when equal amounts of Cyan, Magenta, and
Yellow ink are mixed together.

3.8 Keep Image After Exit (-K or function key K)

The keep image after exit option can be used to leave a
displayed image on the screen when GIFPRT exits. Normally GIFPRT
erases the screen and restores the original display mode upon
exit. However, if you are invoking GIFPRT from a batch (.BAT)
file, or starting it from within another program, you can prevent
the restoration of the original display mode by using the -K
option. It is toggled on and off each time it is used.









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3.9 LCD Screen (-L or function key L)

You can use the LCD screen option to display GIF files on
many laptop displays. These displays often use dark dots to make
up an image, instead of the white dots normally used on graphics
displays. It is toggled on and off each time it is used.

3.10 Map Palette (-M or function key M)

Some types of files, such as Compuserve weather maps, don't
look very good when printed. The reason for this is that when
two different colors with the same intensity are printed, they
look the same. When the -M option is used, the file GIFPRT.MAP
is read and these intensities are assigned to the first 16 colors
of any file being printed or displayed. Since there are a wide
range of color schemes in weather maps, you will probably have to
experiment with the intensities in GIFPRT.MAP.

3.11 Printer Type (-Pn or function keys P,control-F1-F9,1,2)

You can use the printer type option to select the type of
printer. You can get a list of supported printers by typing
GIFPRT -P?, or typing control-F10 in interactive mode. Function
keys control-F1 through control-F9 change the printer type while
in interactive mode. The number keys 1 and 2 change to 2-color
and 8-color mode, respectively.

The current printer type is displayed in the lower-right
hand corner of the screen in interactive mode.

3.12 Quarter Width Display (-Q or function key Q)

The quarter width display option reduces the size of the
display and printout to 1/4 of full-screen width. It is
particularly useful when trying to adjust the brightness and
contrast of an image while printing it, since it lets you print
an image 16-times faster than a full-page image.

3.13 Random Image Select (-R or function key R)

The random image select option, in conjunction with the
slide show option, allows you to set up slide shows where the
order of the images displayed is random. This sometimes makes
slide shows much more interesting.













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3.14 Slide Show (-Sn or function key S)

The slide show option is used to continuously display a
group of GIF files on the screen. When the last GIF file is
displayed, GIFPRT starts over with the first GIF file. Normally
GIFPRT waits for a keypress after displaying a GIF file. With
the slide show option, no keypress is required between GIF files.
The value "n" after the -Sn is approximately the number of
seconds to wait between slides. If "n" is zero, GIFPRT waits for
a key to be pressed before displaying the next image.

3.15 Toshiba T-1000 Display (-T or function key T)

The Toshiba T-1000 display doesn't have a 4 x 3 aspect
ratio, but instead has a 16 x 5 aspect ratio. This option allows
the proportional display of GIF files on this type of laptop
display (when used with the -L option).

3.16 White Screen (-W or function key W)

The white screen option causes a GIF file to be displayed in
black and white instead of color. It is toggled on and off each
time it is used.

3.17 File Information Option (function key ?)

A screen showing information about the currently selected
GIF file is displayed whenever the '?' key is pressed. To return
to the previous screen, press any key.

3.18 Disable EMS Option (-E)

If you use the -E option, GIFPRT won't attempt to use any
available EMS memory to store image data.

4.0 Customizing GIFPRT

If you have a printer that isn't supported by the -P option,
or if you want to use a different print mode, you can customize
your version of GIFPRT by editing the files GIFPRT.PR0 through
GIFPRT.PR8.
















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Each line begins with a three-letter keyword. The "nam"
line is the name of the print mode. The "pin" line contains the
number of pins used in printing (this is the number of bits sent
to the printer per column) followed by the type of printer raster
data. The "dpi" line is the resolution of the printer in the
horizontal and vertical directions, in dots per inch. The "dim"
line is the dimensions of the print area horizontally and
vertically, in dots. The "in1" and "in2" lines describe the
string to be sent to the printer upon initialization in
black/white and color modes, respectively. The "skp" line
describes how to skip row of 'pins'. The "gr1" and "gr2" lines
describe how to output black/white and color graphics,
respectively (a -99 is the length of the data, and a -1
substitutes the raster data for black, -2 for cyan, -3 for
magenta, and -4 for yellow). The "trm" line describes the data to
be send on image termination.

In the in1, in2, skp, gr1, gr2, and trm lines, a single
character by itself is interpreted to mean the ASCII code for
that character, otherwise a numeric field is the decimal
equivalent for the character to send to the printer. You can
also use ESC, CR, LF, FF, and SP instead of these characters'
ASCII values. Any text between "//" and the end of a line is
considered a comment.

The raster types are 0 (Epson, 50% dot density), 1 (Epson,
25% dot density), 2 (Toshiba(Qume), 25% dot density), 3 (HP, 100%
dot density) , and 4 (HP, 50% dot density).





























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