Lightness constancy means that perception of an object’s lightness tends to be perceived as unchanging, despite changes in the amount of light striking the surface of an object. It is generally thought lightness is essentially determined by the percentage of light reflected from an object’s surface. However, it is not clear how the visual system extracts information about object reflectance because the amount of light entering the eye confounds reflectance with the level of illumination in the scene. Several theories and models have been proposed as a solution for this problem. According to the low-level approach, lightness constancy depends on retinal mechanisms and brightness coding in the early visual processing stage. Another class of models considers higher perceptual mechanisms as the base of lightness constancy phenomena. Most influential theories and associated experimental findings are presented in this paper.

lightness perception; brightness perception; lightness constancy; simultaneous contrast