Checker Shadow Illusion
by GDJ - uploaded on June 7, 2015, 2:03 am
The famous checkerboard illusion... I was going to do a version of this but since someone already beat me to it... https://commons.wikimedia.org/wiki/File:Grey_square_optical_illusion.svg . The squares under A and B are the same color. You can test this using any graphics program that has an "eye dropper" (color picker) tool.