Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!fernwood!oracle!news
From: jmarvin@oracle.com
Newsgroups: comp.sys.amiga
Subject: JPEG image compression
Message-ID: <1990Dec4.201018.735@oracle.com>
Date: 4 Dec 90 20:10:18 GMT
Reply-To: jmarvin@oracle.com ()
Organization: Oracle Corporation, Belmont, CA
Lines: 53

In article <1990Nov28.192940.30995@uokmax.ecn.uoknor.edu> drtiller@uokmax.ecn.uoknor.edu (Donald Richard Tillery Jr) writes:
>The 24 bit boards are coming...the 24 bit boards are coming!
> 
>Now for the catch (ain't there always one?)....those 24 bit RGB IFF
>files are HUGE!  I have 11 of them right now and they range from
>300K to almost 850K!
> 
>I have heard of some such algorithms and one type in particular where
>the resulting image IS NOT an exact duplicate of that which started
>out.  But the resulting reduction is up to 90% !  Now if only a .1%
>or less distortion is introduced, I think we can live with that (it
>amounts to about 1 radical pixel every other line) but I don't know
>any specifics about it.  Rumour has it that it is the technique used
>for telephone face-to-face transmissions.  Anyone have any info on
>this?
> 
>Barring that, does anyone have any info on some effective image
>compression techniques that might make use of the 2 dimensional
>quality of images versus the 1 dimentional nature of programs?
>
What you want is the JPEG compression.  It's only a draft
proposal, but it's close enough to use.  To get the spec:

Dr. W. B. Pennebaker
IBM Coproration
Hawthorne Resarch Laboratory
P. O. Box 704
Yorktown Heights, NY 10598
914/784-6566
914/784-6288 (FAX)

Ask for the latest spec (rev 8)

This technique uses Discrete Cosine Transforms and Quantization,
and a good reference on that is:

Discrete Cosine Transform -- Algorithms, Advantages, Applications
K. R. Rao & P Yip
Academic Press  ISBN 0-12-580203-X

And, sorry, I don't have time to whip off a public domain
version for Ami.  But I wanted to seed others who might!
 
>
>Rick Tillery  
>(drtiller@uokmax.ecn.uoknor.edu)
> 

*******************************************************************
* John W. S. Marvin             * There are times when the wolves *
* Oracle Multimedia Development * are silent, and the moon is     *
* jmarvin@oracle.com            * howling...                      *
*******************************************************************