Color constancy: what actually happened.

Color constancy is a feature of the human color perception system which ensures that the perceived color of objects remains relatively constant under varying illumination conditions.

Color constancy is a feature of the human color perception system which ensures that the perceived color of objects remains relatively constant under varying illumination conditions. A green apple for instance looks green at midday, when the main illumination is white sunlight, and also at sunset, when the main illumination is red. This helps with object identification. It is an example of subjective constancy.