This illusion was one of the ten finalists in the 1st annual (2005) "Best Visual Illusion of the Year" contest. It was billed as the "World's Largest Lightness Illusion." In all of the below images the letters, figures, chess pieces, and orbs and their counterparts are all the exact same color. For a detailed explanation read this article in Nature (Image segmentation and lightness perception) or read their shorter explanation submitted with their illusion here. Let's take each image one at a time.
The EVCP, 2005 and the human figures on the left are identical in color to their counterparts on the right, click on the image to view a 4960 x 3508 pixel size image. Scroll back and forth and try to see these figures as the exact same color they are.
Still not convinced maybe a static example isn't good enough click on the image below and view another example of this illusion in motion. Quicktime is required to view this illusion. Both the left and the right orbs are the exact same color at every moment.
Submissions for the 2007 contest are now welcome. Submit your ideas now and take home this prestigious award!
About the contest
"The contest is a celebration of the ingenuity and creativity of the world's premier visual illusion research community. Visual illusions are those perceptual experiences that do not match the physical reality. Our perception of the outside world is generated indirectly by brain mechanisms, and so all visual perception is illusory to some extent. The study of visual illusions is therefore of critical importance to the understanding of the basic mechanisms of sensory perception, as well as to cure many diseases of the visual system. The visual illusion community includes visual scientists, ophthalmologists, neurologists, and visual artists that use a variety of methods to help discover the neural underpinnings of visual illusory perception."