Cornsweet illusion
The Cornsweet illusion, also known as the Craik–O'Brien–Cornsweet illusion and the Craik–Cornsweet illusion, is an optical illusion that was described in detail by Tom Cornsweet in the late 1960s. Craik and O'Brien had made earlier observations in a similar vein.
In the image at left, the entire region to the right of the "edge" in the middle looks slightly lighter than the area to the left of the edge, but in fact the brightness of both areas is exactly the same, as can be seen by blacking out the region containing the edge in the image at right. (Wikipedia)
Cornsweet Illusion
The central line or section creates the impression that one side of the image is darker than the other. But in fact the brightness of both areas is exactly the same, as can be seen by blacking out the region containing the edge.
Cornsweet Illusion
Additional images to demonstrate Cornsweet Illusion.
Cornsweet Illusion
Cornsweet Illusion
The "edge" in the middle of each image is blackened with Photoshop Elements' Replace Color command.
Cornsweet Illusion
Cornsweet Illusion
The "edge" in the middle of each image is blackened with Photoshop Elements' Replace Color command.