============================================================
BIT2GRAY 2.0 -- Convert Black and White Images to Gray Scale
============================================================
Copyright 1989 Brian K. Uechi. All right reserved.

========
Synopsis
========

bit2gray -option [.PCX] [.PCX|.PCC]

-2 = Convert 2x2 non-overlapping cells to 5 level gray scale.
-3 = Convert 3x3 non-overlapping cells to 10 level gray scale.
-4 = Convert 4x4 non-overlapping cells to 16 level gray scale.
-5 = Convert 5x5 non-overlapping cells to 16 level gray scale.
-6 = Convert 6x6 non-overlapping cells to 16 level gray scale.
-7 = Convert 7x7 non-overlapping cells to 16 level gray scale.
-8 = Convert 8x8 non-overlapping cells to 16 level gray scale.

-20 = Convert 2x2 overlapping cells to 5 level gray scale.
-30 = Convert 3x3 overlapping cells to 10 level gray scale.
-40 = Convert 4x4 overlapping cells to 16 level gray scale.
-50 = Convert 5x5 overlapping cells to 16 level gray scale.
-60 = Convert 6x6 overlapping cells to 16 level gray scale.
-70 = Convert 7x7 overlapping cells to 16 level gray scale.
-80 = Convert 8x8 overlapping cells to 16 level gray scale.

-41 = Convert 4x4 non-overlapping cells to 17 level gray scale.
-51 = Convert 5x5 non-overlapping cells to 26 level gray scale.
-61 = Convert 6x6 non-overlapping cells to 37 level gray scale.
-71 = Convert 7x7 non-overlapping cells to 50 level gray scale.
-81 = Convert 8x8 non-overlapping cells to 65 level gray scale.

-410 = Convert 4x4 overlapping cells to 17 level gray scale.
-510 = Convert 5x5 overlapping cells to 26 level gray scale.
-610 = Convert 6x6 overlapping cells to 37 level gray scale.
-710 = Convert 7x7 overlapping cells to 50 level gray scale.
-810 = Convert 8x8 overlapping cells to 65 level gray scale.

========
Examples
========

bit2gray -61 infile outfile
This converts the black and white input file "infile.pcx" to the
gray scale output file "outfile.pcx". The option "-61" selects a 6x6
grid moving 6x6 input pixels per output pixel (non-overlapping mode).
The output file will be padded on the right to make it at least 320
pixels wide. The output file will be a 256 color PCX file although
there will be at most 37 gray levels. The output file will be 1/6
the height and width (padding may make it wider) of the input file.

bit2gray -6 infile outfile.pcc
This converts the black and white input file "infile.pcx" to the
gray scale output file "outfile.pcc". The option "-6" selects a 6x6
grid moving 6x6 input pixels per output pixel (non-overlapping mode).
The output file will be not be padded since it is a cutout file. The
37 possible gray levels will be mapped to 16 gray levels yielding a
16 color PCC output file. The output file will be 1/6 the height and
width of the input file.

bit2gray -40 infile outfile.pcc
This converts the black and white input file "infile.pcx" to the
gray scale output file "outfile.pcc". The option "-40" selects a 4x4
grid moving one input pixel per output pixel (overlapping mode). The
output file will be not be padded since it is a cutout file. The 17
possible gray levels will be mapped to 16 gray levels yielding a 16
color PCC output file. The output file will be approximately the
same height and width as the input file.

============
New Features
============

Version 2.0 removes the memory limitation of version 1.0. BIT2GRAY now
holds only a small portion of the scan in memory during processing. Scans
may be up to 8192 pixels wide; there is no limit of the image length.


===========
Description
===========

BIT2GRAY converts black and white dithered images to gray scale. It works
by moving an NxN grid over the dithered image and counting the number of
white pixels in the grid. This count is used as the gray scale intensity.

BIT2GRAY reads and writes ZSoft Corporation PC Paintbrush (.PCX) files.
It reads black and white PCX files of any size and writes 16 color/gray
scale or 256 color/gray scale PCX files. The 16 gray scale files are best
loaded into PC Paintbrush configured for VGA 640x480x16 colors/gray scale.
The 256 color/gray scale files are best loaded into PC Paintbrush
configured for VGA 320x200x256.

In real life, VGA has only 64 gray levels and a 6x6 grid can have only 37
different gray levels. However, PCX files must be either 16 or 256 color
pictures.

BIT2GRAY can also write ZSoft Corporation PC Paintbrush cutout (.PCC)
files. The difference is PCX files are at least 320 pixels wide for 256
color files or 640 pixels wide for 16 color files. This means there may
be extra padding on the right hand side of the image to force the proper
minimum width. PCC files are only as wide as the image. The reason for
padding is PC Paintbrush sometimes refuses to load PCX files which are not
wide enough. It usually pastes cutout files properly although it ignores
the color palette. I now use the Publisher's Paintbrush paint program
which properly loads both PCX and PCC files.

The DFI HS-3000 hand scanner uses a 6x6 pattern dither so you'll get the
best results by using a 6x6 non-overlapping option. Using other options
usually results in interference lines. The non-overlapping options
greatly shrink the image so always scan at 300 or 400 dpi. Use your
favorite paint program or desktop publishing program to stretch and crop
the scan.

The other options are useful for converting high quality dithered pictures
to gray scale. For example, many MacPaint files exhibit very good
dithering and convert well to 16 level gray scale using the "-4" or "-40"
option.


=====================
Creating GIF pictures
=====================

You can convert gray scale PCX files to GIF format using John Bridges'
CVTGIF 1.4 program. Earlier versions of CVTGIF do not properly convert
256 color PCX files. I use John Bridges' PICEM 1.9b program to view the
images and adjust the contrast and brightness. This program can load PCX
files directly but does not read 256 color PCX files properly.

A typical sequence to create a GIF gray scale scan:

1) Use the DFI HS-300 hand scanner and included SCAN software to create a
300 or 400 dpi scan. Be sure to move the top-left and bottom-right
corners to include as much of the scan as you want. Save the file in PCX
format. If your subject is wide, scan sideways then save it using the F2
'rotate image' option.

2) Run BIT2GRAY with the -6 option for 16 level gray scale or the -61
option for 37 level gray scale. Use the .PCC file type for the output
file if you don't want it padded on the right. For example,

BIT2GRAY -61 MYSCAN MYSCAN61.PCC

3) Run CVTGIF to convert the gray scale PCX file to GIF format. For
example,

CVTGIF MYSCAN61.PCC

The output file will be named MYSCAN61.GIF.


==================
Why use gray scale
==================

Gray scale images can be stretched and resized without the ugly lines and
interference patterns resulting from manipulating dithered images. The
type of dithering used by DFI is particularly susceptible to these defects.


===============
Other utilities
===============

MAC2PCX converts MacPaint format pictures to ZSoft PCX black-and-white
format. The output can be used with PC Paintbrush or converted to
gray scale with BIT2GRAY.

PCX2MAC converts ZSoft PCX black-and-white format pictures to MacPaint
format. MacPaint format doesn't support gray scale so you can't convert
gray scale PCX files. I haven't tried these MacPaint files on a Mac but
all PC MacPaint files viewers I've used accept these files.

INVERT reverses pixel values of ZSoft PCX black-and-white and gray scale
pictures. For black-and-white pictures this means black pixels become
white and white pixels black. For gray scale this means dark pixels
become light and light pixels dark. The result is similar to a photograph
negative.

DOUBLE doubles the length and width of ZSoft PCX black-and-white and gray
scale pictures. The number of pixels actually quadruples. This makes
small pictures more viewable at 640x480 video resolution.


==============
How to find me
==============
If you have any problems or suggestions please let me know. I can be
reached via GEnie, CompuServe, or U.S. mail.

Brian K. Uechi
2616-A Kalihi St.
Honolulu, HI 96819

GEnie: B.UECHI
CompuServe: 72330,155

If you find this program useful, please support the further development of
this and similar programs by sending $15.00 to:

Brian K. Uechi
2616-A Kalihi St.
Honolulu, HI 96819

If you've registered for any version of BIT2GRAY, you are entitled to use
all future versions for no extra charge.


======================
DISCLAIMER OF WARRANTY
======================
THIS SOFTWARE AND DOCUMENTATION ARE PROVIDED "AS IS" WITHOUT WARRANTY OF
ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS OF PURPOSE. YOU ASSUME
THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM AND
DOCUMENTATION. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE ENTIRE
COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.