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Re: 1154bis quick analysis

1993-03-18 15:50:16
To:  nsb(_at_)thumper(_dot_)bellcore(_dot_)com
Subject:     Re: 1154bis quick analysis
Date:        18 Mar 1993  16:32 EST


Yes, those compression schemes have patents behind them. Is this really any
worse than providing for a postscript type? Using it also has legal issues
behind it, but we've glossed over them because Adobe has given its
blessing.

There's an important difference.  Adobe has a trademark on PostScript, but
since they have published the specification to the language, other people
can write PostScript-compatible interpreters, and they don't have to pay
license fees to Adobe.  They just can't call their products "PostScript".

Has anyone considered asking Sperry (or whoever owns the patents these
days) whether it would give similar blessing?

There are several different patents.  Sperry/Unisys owns the patent for the
LZW compression algorithm, a variant of which is used in the UNIX 'compress'
program, but other algorithms are claimed by others.  The LZ77 algorithms
that some would like to use aren't covered under Sperry's patent.

Some claim that the LZ77 is public domain, and some variants of LZ77 appear
to be more effective than UNIX compress.  So maybe we don't need to ask
permission to use it.  But it's difficult to be sure.

Keith

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