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Re: a link to some interesting illusions



The pixels are exactly the same. Take some post-it notes and surround all
of the brown squares on your screen with the post-it notes. The squares all
have the same color.

It is well known that the perception of color depends on the surrounding
color.
The artist Joseph Albers's books and examples are the most famous:
<http://www.amazon.com/exec/obidos/tg/detail/-/0300018460/qid=1043972226/sr=
8-1/ref=sr_8_1/103-6602969-5963002?v=glance&s=books&n=507846>

See also:
<http://www.iscc.org/pdf/demystifying_screen.pdf>
question 6 and myth 6

and for a nice reference:
Principles of Color Technology by Roy S. Berns, pages 23-26.
<http://www.amazon.com/exec/obidos/tg/detail/-/047119459X/qid=1043972277/sr=
1-1/ref=sr_1_1/103-6602969-5963002?v=glance&s=books>

or
Human Color Vision by Peter Kaiser and Robert Boynton.

Larry Woolf;General Atomics;San Diego CA
92121;Ph:858-526-8575;FAX:858-526-8568; www.ga.com; www.sci-ed-ga.org

-----Original Message-----
From: Bob Sciamanda
Sent: Thursday, January 30, 2003 2:32 PM
Subject: Re: a link to some interesting illusions


Very interesting!
Skeptics should be shown the RGB values of relevant pixels, by using
PhotoShop, or other viewers which show this info.

I suspect the striking success of Illusion #2 capitalizes on the fact that
"brown" is not a spectral color and so is more subjective in character -
depending greatly on surrounding colors.

| http://www.adm.duke.edu/alumni/purves/