Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!zaphod.mps.ohio-state.edu!lavaca.uh.edu!uhnix1!sugar!peter
From: peter@sugar.hackercorp.com (Peter da Silva)
Newsgroups: alt.sources.d
Subject: Re: Compressing alt.sex.pictures files
Message-ID: <6483@sugar.hackercorp.com>
Date: 30 Aug 90 02:32:30 GMT
References: <1990Aug27.154419.25882@mcs.anl.gov> <1990Aug28.192024.22435@zorch.SF-Bay.ORG> <6467@sugar.hackercorp.com> <eillihca.651947189@fizzle.stanford.edu>
Reply-To: peter@sugar.hackercorp.com (Peter da Silva)
Organization: Sugar Land Unix - Houston
Lines: 14

In article <eillihca.651947189@fizzle.stanford.edu> eillihca@fizzle.stanford.edu (Achille Hui) writes:
> peter@sugar.hackercorp.com (Peter da Silva) writes:
> >I believe that XORing alternate scan-lines and run-length-encoding the result
> >would do a better job.

> 2) XOR neighbouring scan lines in raw image and then compress it.
> 3) subtract neighbouring ......
> 2,3)	~ 110% [of original]

Yes, but as Kent pointed out later on, LZW is poorly adapted to dealing with
that sort of data set. Have you tried run-length encoding?
-- 
Peter da Silva.   `-_-'
<peter@sugar.hackercorp.com>.