weird, how does it work?

[cotambear]

http://www.johnsadowski.com/big_spanish_castle.html#

[Hobbsy]

i saw this and didnt get if it was supposed to be funny or what?

a rollover image is no optical illusion.

[LivinLOS]

did you look for a while ???

The point being your eyes adjust to the opposite color in the initial image and compensate (kind of like image retention) and so when the black and white image appears if your eye stays still and doesnt roam the image the opposite color is hinted at by the eye into the image and the brain then processes green grass etc..

As your eye moves about and as the color retention fades the image then goes to its real black and white state..

Same effect if you wear green / red or blue lensed glasses for a while and take them off the world goes to the opposite side of the spectrum as your head has been compensating for the filter and over compensates for a while..

Perception and cognition are always linked, only a small area of your eye is actually set up to recieve color info.. The rest is 'filled in' by the brain adding color to the peripheral vision.. Same with many auditory effects or touch.. Ever put an ice cold spoon on someone after making out it was hot enough to burn ?? They yelp and feel burnt by 'hot' but its not.