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From: raymond@cosc.canterbury.ac.nz (R P Wilson )
Newsgroups: comp.compression
Subject: Q-Coders (again... )
Message-ID: <1991May8.104151.658@csc.canterbury.ac.nz>
Date: 7 May 91 22:41:50 GMT
Organization: Computer Science,University of Canterbury,New Zealand
Lines: 18
Nntp-Posting-Host: cosc.canterbury.ac.nz


OK compressor heads, who can tell me roughly what sort of speed improvement
a binary alphabet fax image compressor will gain if it starts using a Q-coder
to quantise values to powers of 2 (and gets rid of a multiply per compressed
bit and a divide per decompressed bit)?

How much extra overhead would there be involved in doing this?

On a Sun 4/490 this code compresses a fine mode fax (1728x2376) in 35 seconds
and decompresses it in 55 seconds.

Raymond.

--
Raymond Wilson.	email:	raymond@cosc.canterbury.ac.nz
		snail:	c/- Computer Science Department,
			University of Canterbury,
			New Zealand.