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ppmtogif - convert a portable pixmap into a GIF file
ppmtogif
[-interlace] [-sort] [-map mapfile] [-transparent color] [-comment text]
[ppmfile]
All options can be abbreviated to their shortest unique prefix.
Reads
a portable pixmap as input. Produces a GIF file as output.
This program
creates only individual GIF images. To combine multiple GIF images into
an animated GIF, use gifsicle.
ppmtogif creates either an original GIF87
format GIF file or the newer GIF89 format. It creates GIF89 when you request
features that were new with GIF89, to wit the -transparent or -comment options.
Otherwise, it creates GIF87. Really old GIF readers conceivably could
not recognize GIF89.
- -interlace
- Produce an interlaced GIF file.
- -sort
- Produces a GIF file with a sorted color map.
- -map
- mapfile
Uses the colors
found in the mapfile to create the colormap in the GIF file, instead of
the colors from ppmfile. The mapfile can be any ppm file; all that matters
is the colors in it. If the colors in ppmfile do not match those in mapfile
, they are matched to a "best match." A (much) better result can be obtained
by using the following filter in advance:
ppmquant -floyd -map mapfile
- -transparent
color
- Mark the given color as transparent in the GIF file. The color is
specified as in ppmmake(1)
.
- -comment text
- Include a comment in the GIF output
with comment text text. Without this option, there are no comments in the
output.
giftopnm(1)
, ppmquant(1)
, pngtopnm(1)
, gifsicle(1)
<http://www.lcdf.org/gifsicle
>,
ppm(5)
.
Based on GIFENCOD by David Rowley <mgardi@watdcsu.waterloo.edu>.
Lempel-Ziv compression based on "compress".
Copyright (C) 1989 by Jef Poskanzer.
If you use ppmtogif, you are using a patent on the LZW
compression method which is owned by Unisys, and in all probability you
do not have a license from Unisys to do so. Unisys typically asks $5000
for a license for trivial use of the patent. Unisys has never enforced
the patent against trivial users. The patent expires in 2003.
Rumor has
it that IBM also owns a patent covering ppmtogif.
A replacement for the
GIF format that does not require any patents to use is the PNG format.
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