Afterimage

An effect of Photobleaching Photoreceptors. As your retina stares at a color, it will disproportionately Photobleach the Cones that are most sensitive to that color. While the Cones are still Photobleached, exposing them to a white image – which would ordinarily excite all cones similarly – excites the Photobleached cones less, and therefore gives the perception of the Complementary Color of the previous color.

This can also be performed with complex images. A famous one is the American Flag in the Complementary Colors to Red, White and Blue: Cyan, Black and Orange. Stare at the center of the image for 15-30 seconds, then stare at a white surface to see the normal American Flag as an Afterimage.