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From: UD069225@NDSUVM1.BITNET (Eric H. Romo)
Newsgroups: comp.sys.mac,comp.sys.mac.programmer,comp.sys.ibm.pc,comp.sys.ibm.pc.programmer
Subject: Re: Mac/IBM text compression?
Message-ID: <4149UD069225@NDSUVM1>
Date: 15 Jun 90 22:37:32 GMT
References: <41855@apple.Apple.COM> <1990Jun11.224021.23941@agate.berkeley.edu> <30796@cup.portal.com>
Organization: North Dakota Higher Education Computer Network, Fargo, ND
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DISCLAIMER: Author bears full responsibility for contents of this article.

At Simtel20.arpa, there is a file that compares(tests) out all the
popular compression programs for PCs(ARC, ZOO, ZIP, and more) with
different input(GIF, text-only, executables) and ranks them with
respect to % compression and speed. Its an arc'd text file,
see pd:<msdos.arc-lbr>compres8.arc, which gives the tables of data,
and normalized ratings as well.

I thought it was known that GIF files are LZW compressed(thats part of the
GIF format.), therefore its curious to see that anyone would try compressing
a compressed file. I would guess that the only extra compression might be a
small amount by doing a huffman encoding on the GIF file, but doing a second
pass with LZW would be fruitless(see those tables, none of the compressors
even dented a GIF file, some even increased in size after compression.)

Eric Romo