Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!mcsun!hp4nl!sci.kun.nl!ge
From: ge@dbf.kun.nl (Ge' Weijers)
Newsgroups: comp.compression
Subject: Re: looking for info on image compression
Message-ID: <2898@wn1.sci.kun.nl>
Date: 27 Mar 91 10:51:28 GMT
References: <5040@ns-mx.uiowa.edu> <5043@ns-mx.uiowa.edu> <12481@pt.cs.cmu.edu> <1991Mar26.071543.18336@cbnewsh.att.com>
Sender: root@sci.kun.nl
Lines: 15

wcs@cbnewsh.att.com (Bill Stewart 908-949-0705 erebus.att.com!wcs) writes:

>Another cheap method, which can often provide good results
>(at least for black&white), is to first take the difference
>between each row and the previous one, and then use the 1-d-left-to-right
>Lempel-Ziv or Huffman or whatever.

That's probably why group 3 fax machines use it, with a fixed Huffman table.

Ge'
--
Ge' Weijers                                    Internet/UUCP: ge@cs.kun.nl
Faculty of Mathematics and Computer Science,   (uunet.uu.net!cs.kun.nl!ge)
University of Nijmegen, Toernooiveld 1         
6525 ED Nijmegen, the Netherlands              tel. +3180652483 (UTC-2)