Subject: RDS effects

From: [email-masked] (Dennis Kier)
Date: 7 Nov 92 20:41:00 GMT

References: <[email-masked]>

  [email-masked] (Matthew Davey)MD  wrote:
MD>
MD>Another little thing: once I got the hang of focussing on things that
MD>weren't there for playing with Stereograms I tried the same trick with
MD>other things.  Taking almost any regular pattern, such as a wire fence

This will often work for the regular patterns in print adds, or the
printing inside envelopes - companies do this a lot. Sometimes the
printer will use odd patterns that cause the result to look like
shingles, or you can see different levels with different angles of your
eyes.

Stereo World magazine had an article on this sort of repeated pattern on
candy wrappers, and other things. I now have a collection, mostly from
the inside printing on envelopes.

Dennis
[email-masked]

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From: [email-masked] (Daniel Green)
Date: 10 Nov 92 01:33:41 GMT

> the inside printing on envelopes.
 
Has anyone else noticed that the x-eyed technique provides a really fast
way to solve those puzzles that show two pictures that have only a few
subtle differences?  Fuse those image pairs, and the differences pop right
out as sort of sparkly areas.

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Daniel Green
[email-masked]
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From: [email-masked] (Charles Neveu)
Date: 10 Nov 92 20:36:54 GMT

>out as sort of sparkly areas.

Yes! Classic example of parallelizing a serial search problem.  

By the way, the "sparkly areas" are called "lustre", which is why
shimmery things look shimmery - the two eyes are getting very
different images, in local areas, areas which the visual system
expects to pretty closely resemble each other. Wavy specular surfaces
show this, so do minerals like tiger's eye. It's also the reason some
shiny things looks shimmery when viewed through cross polarized 3-d
glasses: one lens passes the reflection which the other blocks it.

So it's interesting that you describe it as "sparkly", since there's
no sparkle in the printed image. Our visual system interprets strong
binocular differences as shinyness. 

Charles Neveu  ([email-masked])
Neurology Unit
Program in Physiological Optics
UCBerkeley