Magic Castle

Press play. Stare at the dot in the middle of the video.




What you see is an "afterimage", created due to "neural adaptation".

Nerve cells in your eye, stop responding to a stimulus after a period of time. So when you stare at the color image the neurons in the retina stop responding to the chemical signals triggered by the colors.

When you look at the black and white version, your eyes are receiving white light which contains all wavelengths which triggers the release of chemicals for all colors. But since the neurons in the retina have stopped responding to the previous colors you only "see" the opposite colors, generating the correctly colored version.