The checker shadow illusion is an optical illusion published in 1995 by Edward Adelson, an American professor of vision science at the Massachusetts Institute of Technology. The phenomenon features an image of a checkerboard with light and dark squares, partly shadowed by another object, such as a cylinder as in this illustration. The optical illusion is that the area labeled A appears to be darker than the area labeled B. However, within the context of the two-dimensional image, they are of identical brightness – in other words, they would be printed with identical mixtures of ink, or displayed on a screen with pixels of identical color.Optical illusion credit: Edward Adelson; illustrated by Pbrks