Brightness contrast with color: cube

Just as achromatic patches can be made to look differently bright by empirical information, color patches can be dramatically affected by empirical cues about the amount of illumination they are likely to be under. In this example, the effect is primarily on the color brightness of the relevant tiles rather than on sensations of hue or saturation as such.

(Image by Beau Lotto - www.lottolab.org)