giftrans(1): transform gif from gif87 to gif89 ...

NAME

giftrans - transform gif from gif87 to gif89, making one color transparent

SYNOPSIS

giftrans [options] [-o filename] filename

DESCRIPTION

giftrans converts any GIF file into a GIF89a. Allows for setting the transparent or background color, changing colors, adding or removing comments. Also code to analyze GIF contents.

OPTIONS

-h: Print short help on stdout.
-t: Specify the transparent color
-T: Index of the transparent color is the background color index
-B: Specify the transparent color's new value
-b: Specify the background color
-g: Change a color in the global color table
-c: Add a comment
-C: Remove old comment
-l: Only list the color table
-L: Verbose output of GIFs contents
-V: Verbose output while converting
-o: Redirect stdout to a file
-e: Redirect stderr to a file

Colors may be specified as index, as rgb.txt entry or in the #rrggbb form.

EXAMPLE

To convert the white background of a gif file to transparent, use

giftrans -t #ffffff file.gif > transparentfile.gif

This program has been tested on a HP9000/720 with HP-UX A.08.07 In this environment, neither lint -u nor gcc -Wall produce any messages. If you encounter any errors or need to make any changes to port it to another platform, please contact me.

Known bugs:

-B flag won't work if there's an Extension between the Global Color Table and the Image Descriptor (or Graphic Control Extension). If -V has been specified, a Warning Message will be displayed. Will be fixed in 2.0

Always outputs GIF89a. Shouldn't do this if version is newer.

-D option may output changed data instead of original data, use with caution, best only with then -L option.

COPYRIGHT

Permission to use, copy, modify, and distribute this software for any purpose and without fee is hereby granted, provided that the above copyright notice appears in all copies. This software is provided "as is" and without any express or implied warranties.

VERSION HISTORY

Version 1.11 - 21.7.94: Moved Plain Text Extension to the Extensions section where it belongs Accept Unknown Extension Labels Incorporated MS-DOS port by enzo@hk.net (Enzo Michelangeli) Added -o and -e options to redirect stdout and stderr Added -D debug flag
Version 1.10.2 - 22.6.94: Support for -DRGBTXT flag
Version 1.10.1 - 21.6.94: Different rgb.txt file FreeBSD/386BSD
Version 1.10 - 19.6.94: Added option to change a color in the global color table Added option to change the color for the transparent color index
Version 1.9.1 - 7.6.94: Different rgb.txt files for X11 and Open Windows
Version 1.9 - 1.6.94: Fixed a bug which caused color names to be rejected.
Version 1.8 - 30.5.94: Accept #rrggbb style arguments. Do nothing if rgb-color not found in GIF.
Version 1.7 - 16.5.94: Added -l option to only list the color table. Added -L option for verbose output without creating a gif. Added -b option to change the background color index. Display all matching color names for color table entries. Fixed a bug which caused bad color names if rgb.txt starts with whitespace. Doesn't use strdup anymore. Fixed =& bug on dec machines.
Version 1.6 - 5.4.94: Added color names recognition.
Version 1.5 - 15.3.94: Added basic verbose output to analyze GIFs.
Version 1.4 - 8.3.94: Fixed off-by-one bug in Local Color table code. Added option to add or remove a comment. Transparency is no longer the default.