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

Bugs

       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

       Copyright (c) 24.2.94 by Andreas Ley <ley@rz.uni-karlsruhe.de>

       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.

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.

Example

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

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

Name

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

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. Of course, beware that  shells
       will often consider the # character to start a comment and so you may have to escape it!

Synopsis

giftrans [options] [-o filename]filename

Thanks

       Thanx for bug reports, ideas and fixes to

              patricka@cs.kun.nl (Patrick Atoon)

              wes@msc.edu (Wes Barris)

              pmfitzge@ingr.com (Patrick M. Fitzgerald)

              hoesel@chem.rug.nl (frans van hoesel)

              boardman@jerry.sal.wisc.edu (Dan Boardman)

              krweiss@chip.ucdavis.edu (Ken Weiss)

              chuck@trantor.harris-atd.com (Chuck Musciano)

              heycke@camis.stanford.edu (Torsten Heycke)

              claw@spacsun.rice.edu (Colin Law)

              jwalker@eos.ncsu.edu (Joseph C. Walker)

              Bjorn.Borud@alkymi.unit.no (Bjorn Borud)

              Christopher.Vance@adfa.oz.au (CJS Vance)

              pederl@norway.hp.com (Peder Langlo)

              I.Rutson@bradford.ac.uk (Ian Rutson)

              Nicolas.Pioch@enst.fr (Nicolas Pioch)

              john@charles.CS.UNLV.EDU (John Kilburg)

              enzo@hk.net (Enzo Michelangeli)

              twv@hpwtwe0.cup.hp.com (Terry von Gease)

              k.rusch@ieee.org (Klaus Johannes Rusch)

              omerzu@quantum.de (Thomas Omerzu)

              Willem.Vermin@sara.nl (Willem Vermin)

              wjones@tc.fluke.COM (Warren Jones)

Version History

Version 1.12.2 - 11.4.96
Changed to GNU copyright

Version 1.12.1 - 9.2.96
Fix for multi-word color names.

Version 1.12 - 17.2.95
Incorporated dumpcomment by omerzu@quantum.de (Thomas Omerzu)
Outputs original version if newer than GIF89a.

Version 1.11.2 - 14.12.94
Incorporated OS/2 port by k.rusch@ieee.org (Klaus Johannes Rusch)
Different rgb.txt file for OS/2, setmode replaced by freopen for
OS/2 (SAA C)

Version 1.11.1 - 11.8.94
Allows for use of the -g option without the -B option.

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.

This man file made 9.8 from documentation in the program source code by Kai Nordlund
(knordlun@fltxa.helsinki.fi).