On Jun 22, 11:45 am, Chris L Peterson wrote:
On Fri, 22 Jun 2007 18:28:36 +0100, "OG"
wrote:

This is one of the very best examples I've seen of this
http://www.popularscience.co.uk/features/feat16.htm

Very good. Look at these,http://www.nature.com/neuro/journal/...1199_1010.html, for
similar examples with color.

Basically, the eye/brain is very poor at discriminating absolute
intensities or colors.

Some others in the same vein:

http://gpsinformation.info/main/Moving.html
http://gpsinformation.info/main/JYimages.html
http://gpsinformation.info/main/grayscale.html
http://gpsinformation.info/main/humor.htm

Another one that really surprised me the first time I saw it was
"a" Moon illusion. Not the one when the Moon appears larger
on the horizon than when higher, but when craters look like
mountains. Best I can determine it's caused by a lighting
effect (the position of the Moon with respect to the Sun); it's
quite amazing.