gifencode
(?s)Based on GIFENCODE.*Permission to use
(?s)This code is loosely based on ppmtogif from the PBMPLUS distribution
of Feb. 1991.  That file contains the following copyright notice:
\s+Based on GIFENCODE by David Rowley <mgardi@watdscu.waterloo.edu>.
\s+Lempel-Ziv compression based on "compress" by Spencer W. Thomas et al.
\s+Copyright \(C\) 1989 by Jef Poskanzer.
\s+Permission to use, copy, modify, and distribute this software and its
\s+documentation for any purpose and without fee is hereby granted, provided
\s+that the above copyright notice appear in all copies and that both that
\s+copyright notice and this permission notice appear in supporting
\s+documentation.  This software is provided "as is" without express or
\s+implied warranty.
\s+We are also required to state that
\s+"The Graphics Interchange Format\(c\) is the Copyright property of
\s+CompuServe Incorporated. GIF\(sm\) is a Service Mark property of
\s+CompuServe Incorporated."