The checker shadow illusion is an optical illusion published by Edward H. Adelson, Professor of Vision Science at MIT in 1995. The image depicts a checkerboard with light and dark squares. The optical illusion is that the area of the image labeled A appears to be a darker color than the area of the image labeled B.
However, they are actually exactly the same color.
This can be proven using the following methods:
- Opening the illusion in an image editing program and using the eyedropper tool to verify that the colors are the same
- Isolating the squares. Without the surrounding context, the effect of the illusion is dispelled. This can be done by using the selection tool in some image editing programs.
- Using a photometer
- Connecting the squares with a rectangle of the same color, as seen below