Ghost Colors

This is one of my earliest color optical illusions. There is no yellow or green in the diamond shapes, just vertical black lines! (If you don’t believe it, use a eyedropper tool to check it.)

Illusory colors
Ghost Squares (2007)

Below are the animated versions of my op art:

rotating ghost square 1
There is no yellow in this GIF!
There is no green in this GIF!

Some intriguing variants. The yellowish and greenish spirals within the radiating patterns are actually made of black segments.

Ghost color spirals

Related illusion: illusive color radial beams