In 32 tips to get ideas to spend your free time is a drawing of a sun, giving the optical illusion that the inner circle is much whiter than the surrounding white outside the drawing. A former colleague even made an airbrush in which the inside of such a form was darker than the environment, and still it seemed lighter.
So I wanted to examine that. How much black can I add until the inner shape seems darker than the outer space? It turns out that there may be around 5 to 8% black added to the white before the effect is eliminated. Pretty much, isn’t it? It’s way more than I expected.
And in the example above you can also see how much influence colors and shades have on each other. The shape on the right side is the tint I used in the inner circle!
The gray of Adelson
Another great example is at the bottom of this blogpost. I find it hard to believe my eyes, but the proof is laid out in the video.