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From: gwing@mullauna.cs.mu.OZ.AU (Geoff C Wing)
Newsgroups: comp.compression
Subject: Re: JPEG compression errors ?!
Message-ID: <gwing.676052960@mullauna>
Date: 4 Jun 91 16:29:20 GMT
Article-I.D.: mullauna.gwing.676052960
References: <AD1NgIeaKC@s514.ipmce.su>
Sender: news@cs.mu.OZ.AU
Distribution: aus
Organization: Comp Sci, University of Melbourne, Australia
Lines: 15

leo@s514.ipmce.su (Leonid A. Broukhis) writes:
>There are some GIF images (320x200,256) which have inacceptable
>distortions (green dots on human face, lack of luminance, etc)
>after conversion to JPEG (even with quality > 100!!),
>and these distortions are independent of the quality.

>	Is this due to incorrectness of the JPEG implementation
>or due to JPEG algorithm?
It's due to the algorithm. JPEG achieves such excellent compression ratios for
picture and sound data at the expense of exact representation. It's a quality
sacrifice to gain quantity.
  |        Geoff C Wing       |         \   _  _ _ _  __
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  |gwing@munmurra.cs.mu.oz.au |    \X/ /\ \ |  | _|_ \__| //\\
  |static@phoenix.pub.uu.oz.au|