Re: Mark IV compression

[hjohnson@pluto.njcc.com (Herbert R Johnson)]

On Mon, 30 Apr 2001 16:48:53 -0500, Tom Droege <tdroege@veriomail.com> wrote:
*>Chris and all,
*>
*>[Compression] sounded like a great idea since the promised 1/3 would make a big
*>difference in the job of sending out Disk Set 18.  So I took a data disk of 
*>668 MBytes and ziped it with WinZip.  This produced a file of 426 
*>MBytes.   A saving, but barely enough to be worth the effort.
*>
*>I assume this is because there is a lot of noise on these disks compared to 
*>other images.  Noise is hard to compress.
*>
*>So is there a better "lossless" compressor?  Many of you have disks to try 
*>your favorite on.
*>

TASS Tech Note #55 is on Mark III and IV compression. GZip was tested and
provided 1/3 reduction. Other methods are discussed. The Tech Note is
drawn from prior discussion and testing from various TASS members. Arne
subsequently mentioned hcompresss, that too is in there.

Herb Johnson
 

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