I got that link via email this morning, along witht he following message:
It really messes with your head, but Square A and Square B are on the exact same shade of gray. You can take it in to Photoshop like I did if you don’t believe it.
So I did, and they are. I love stuff like this. There’s also a link to a page explaining what your eye is doing to create the effect.
Update: There’s also some other neat links on this page (including that checkered shadow illusion)
Edited on Sep 30th 2002, 17:10 by Hooloovoo