What is White's illusion?

White's illusion is a brightness illusion where certain stripes of a black and white grating is partially replaced by a gray rectangle. Both of the gray bars of A and B are the same color and opacity. The brightness of the gray pieces appear to shift toward the brightness of the top and bottom bordering stripes. This is in apparent opposition to lateral inhibition as it cannot explain this occurrence. This occurs even when the gray patches in the black stripes are bordered by more white than black. A similar illusion occurs when the horizontal strips have different colors; this is known as Munker–White's illusion, Munker's illusion, or Bezold effect.