Benham's Top

Description:

Benham's top is one of many classic examples of subjective colors. One should be able to see faint colors in the positions of the arcs of the black-and-white spinning circular disk. The saturation of the perceived colors can be adjusted by spinning speed. Different sections of the arcs produce different colors from reddish to bluish. Reversing the spinning reverses the order of colors.

Touching the disk stops the spinning.

This is the smartphone version of the free online Benham's Top:

http://www.biyee.net/color-science/benham-top/