Brightness Constancy

Brightness Constancy is how we perceive an object as having a constant lightness even when its illumination varies. We also perceive an object as having relative luminance, which means that the amount of light an object reflects is related to its surroundings. An example of this could be the two candles. One is directly in the light while the other is not, changing the colors of them. However, we still perceive them as being the exact same color.