Checker Shadow Illusion

The Checker Shadow Illusion is a popular optical illusion that demonstrates how our perception of color and brightness can be influenced by the context in which those colors appear. In this illusion, two squares on a checkerboard pattern appear to have different shades of gray, but in reality, they have the same color. Wikipedia - The squares marked A and B are the same shade of gray

Here's a simple explanation using a common example:

Imagine you're looking at a checkerboard pattern, with alternating light and dark squares. Now, picture a cylinder casting a shadow over part of the checkerboard. Due to the shadow, some of the light squares are in the shadowed area, making them appear darker than they actually are. At the same time, some dark squares are in the lit area, making them appear lighter than they actually are.

In the Checker Shadow Illusion, there is one light square (let's call it Square A) in the shadowed area and a dark square (Square B) in the lit area that have the same shade of gray. However, because our brain takes into account the surrounding c ...