The White's Illusion is an optical illusion created by Edward H. White in the late 19th century. It consists of a grid of black and white squares, arranged in a checkerboard pattern. When viewed from a distance, the grid appears to be composed of alternating light and dark squares
From Wikipedia
White's illusion is a brightness illusion in which certain stripes of a black-and-white grating are replaced by gray rectangles of the same color, luminance, and opacity. The brightness of the gray rectangles appears to be closer to the brightness of the top and bottom bordering stripes. This is opposite to any explanation based on lateral inhibition; hence it cannot explain the illusion.