ppmtogif

Section: User Commands (1)
Updated: 20 May 2000
Index Return to Main Contents
 

NAME

ppmtogif - convert a portable pixmap into a GIF file  

SYNOPSIS

ppmtogif [-interlace] [-sort] [-map mapfile] [-transparent color] [ppmfile]  

DESCRIPTION

Reads a portable pixmap as input. Produces a GIF file as output.  

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). Note that this option outputs a GIF89a format file which might not be understood by your software.

All flags can be abbreviated to their shortest unique prefix.  

SEE ALSO

giftopnm(1), ppmquant(1), pngtopnm(1), 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.


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
SEE ALSO
AUTHOR
LICENSE

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Time: 19:27:48 GMT, January 23, 2025