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From: ken@turtlevax.UUCP (Ken Turkowski)
Newsgroups: net.dcom,net.micro
Subject: Re: Squeezing files.
Message-ID: <789@turtlevax.UUCP>
Date: Wed, 19-Jun-85 15:44:58 EDT
Article-I.D.: turtleva.789
Posted: Wed Jun 19 15:44:58 1985
Date-Received: Thu, 20-Jun-85 03:57:19 EDT
References: <1414@ecsvax.UUCP> <784@turtlevax.UUCP> <1861@ukma.UUCP>
Reply-To: ken@turtlevax.UUCP (Ken Turkowski)
Organization: CADLINC, Inc. @ Menlo Park, CA
Lines: 37
Xref: utcs net.dcom:1045 net.micro:10496

In article <1861@ukma.UUCP> sean@ukma.UUCP (Sean Casey) writes:
>In article <784@turtlevax.UUCP> ken@turtlevax.UUCP (Ken Turkowski) writes:
>>I think you should consider changing to Lempel-Ziv Compression (posted
>>to the net as "compress", version 3.0), which normally gives 70%
>>compression (30% of original size) to text.  The program is fast, and
>>adapts to whatever type of data you give it, unlike static Huffman
>>coding.  It usually produces 90% (!) compression on binary images.
>
>WHOA BUDDY!
>
>Lempel-Ziv doesn't do NEARLY that well.  We've been using it for
>months, and we've found that text and program sources usually get about
>55-65% compression, while binaries get about 45-55% compression.  This
>is encountered in the optimal case of compressing a large archive of
>files.  As files get smaller, expecially as they drop below about 8k in
>size, compression worsens. I seriously doubt that most binaries contain
>only 10% of unambiguous information, much less being compressable to
>that size.

I can see that we have a semantic problem here.  By "image", I mean a
picture, or two-dimensional signal.  By "binary", I mean ones and
zeros, black and white, no grey-scale, no color.  A binary image is
then a coarsely quantized picture, with lots of runs of zeros and
ones.  L-Z does exceptionally well on these type of data, and I will
reiterate my claim of 90% average compression.

As far a program source code and executable machine code, I get the
same types of compression ratios as you.

I'm curious; what is the etymology of the word "binary" as it is
sometimes used to refer to executable machine code?  And why does it
imply program rather than data?
-- 

Ken Turkowski @ CADLINC, Menlo Park, CA
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