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From: barham@adm.csc.ncsu.edu (Paul T. Barham)
Newsgroups: sci.psychology,comp.graphics.visualization
Subject: Re: Real 3D PHOTOCOPY - black & white - no glasses...
Message-ID: <1991Apr30.112127.2524@ncsu.edu>
Date: 30 Apr 91 11:21:27 GMT
References: <4354.2816ba40@iccgcc.decnet.ab.com> <1991Apr29.225451.24699@cs.umn.edu>
Sender: news@ncsu.edu (USENET News System)
Organization: North Carolina State Department of Computer Science
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What you saw may have actually have been an autostereogram.  From the
abstract of a paper describing autostereograms:

   "A new technique for the presentation of cyclopean stereograms is
described, in which complete information for the two eyes is contained
in a single, printed image.  Such "autostereograms" may be generated to
contain an unlimited range of 3-D depth forms within certain
constraints."

The article is entitled "The Autostereogram" and appears in the SPIE
Proceedings, Volume 1256, Stereoscopic Displays and Applications.  The
authors are Tyler and Clarke.

Hope this helps.

***************************************
Paul T. Barham
barham@adm.csc.ncsu.edu
Computer Science Department
North Carolina State University
***************************************