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Name

ppmtogif - convert a portable pixmap into a GIF file

Synopsis

ppmtogif [-interlace] [-sort] [-map mapfile] [-transparent color] [-comment text]

[ppmfile]

All options can be abbreviated to their shortest unique prefix.

Description

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.

Options

-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.

See Also

giftopnm(1) , ppmquant(1) , pngtopnm(1) , gifsicle(1) <http://www.lcdf.org/gifsicle >, ppm(5) .

Author

Based on GIFENCOD by David Rowley <mgardi@watdcsu.waterloo.edu>. Lempel-Ziv compression based on "compress".

Copyright (C) 1989 by Jef Poskanzer.

License

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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