Path: utzoo!utgpu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!rpi!uupsi!sunic!dkuug!iesd!iesd.auc.dk!fischer
From: fischer@iesd.auc.dk (Lars P. Fischer)
Newsgroups: comp.graphics,alt.sex.pictures
Subject: Re: JPEG compression
Message-ID: <FISCHER.91Jan15185003@thiele.iesd.auc.dk>
Date: 15 Jan 91 18:50:03 GMT
References: <1991Jan15.061755.24549@cunixf.cc.columbia.edu>
Sender: news@iesd.auc.dk (UseNet News)
Organization: Mathematics and Computer Science, University of Aalborg
Lines: 42
In-reply-to: mfr3@cunixb.cc.columbia.edu's message of 15 Jan 91 06:17:55 GMT

>>>>> On 15 Jan 91, mfr3@cunixb.cc.columbia.edu (Matthew F Ringel) said:

Matthew> A couple of days back, someone posted to alt.sex.pictures,
Matthew> with a picture that was in (a uuencoded form of) JPEG
Matthew> compression. [...] Does anyone think that this could become one
Matthew> of the new standards for posting to alt.sex.pictures?

Using JPEG format for picture exchange would certainly be a good idea.
JPEG achieves effective compression and is (shortly) an international
standard. With the advent of JPEG implementations in hardware (C-Cube,
NeXTdimension), handling JPEG format will even be very effective.
JPEG is destined to be a major graphics format.

There are currently a number of problems, though:

1) JPEG can distort the the picture (slightly), i.e. the picture is
not guaranteed to be the same when unpacked. The effect is minor for
small degrees of compression (<*25), but it might still be a problem in
some cases (for alt.sex.pictures you wouldn't mind, of course :-).

2) If we are to use JPEG as the standard for exchange, we must all
have a JPEG compatible program, either a viewer or as a JPEG2GIF
program. There should be JPEG programs for all common platforms (and
even for a few of the more arcane, such as the IBM PC). This implies
that source for such programs must be available -- the JPEG program
posted recently was a PC binary, if I'm not mistaken. Also, JPEG
programs must be freely available to all -- the JPEG program posted
was a *shareware* -- as we cannot use a image standard that will cost
us all $$$. People are simply not going to use it.

So, the idea of using JPEG as a USENET image standard is fine, if a
bit premature. In a few years time, when freely distributeable, no
cost, source code JPEG software is available, I suspect it will be
exactly what we will do. In the meantime .... 

Oh, I haven't checked recently -- will JPEG be in the next release of
PBM?

/Lars
--
Lars Fischer,  fischer@iesd.auc.dk    |  Life is hard, and then you die.
CS Dept., Univ. of Aalborg, DENMARK.  |             - The Immaterial