GIF used the Limpel-Ziv-Welsh compression algorythm, which was patented in 1985 based on the fact that the same algorythm had also been implemented in hardware only.
The LZW patent has expired. JPEG used a Limpel-Ziv compression algorythm that was not patented, and was implemented/adopted by a standards organization then implemented by college freshmen using publicly available information - assuring that it could not be patented. PNG has it's own advantages in both it's lack of intellectual property rights encumbrances, as well as it's original implementation in Open Source. Ironically, PNG uses a more effecient compression algorythm that was implemented in GNU Public License source code. There are enough PNG images out there that it is likely to continue to survive, but now that the LZW patents have expired, the LZW code is effectively "public domain". One of the down sides of patent applications is that after 19 years, the details of the implementation become public domain and anyone can implement your device without paying royalties. Since the "implementation" of a patented device in software is the source code and algorythm, both become public domain when the patent expires. You might want to check with a patent lawyer to confirm this. _______________________________________________ Gnu-misc-discuss mailing list [email protected] http://lists.gnu.org/mailman/listinfo/gnu-misc-discuss
