Color is a psychological property of our visual experience when we looked at objects and lights, not a physical property of those objects or lights. Color is more accurately understood as a sensation created in the brain. In natural viewing, colored objects are seen within a complex surrounding context. The change in color appearance caused by introducing nearby light is called chromatic induction. There are two different types of induction: chromatic contrast and chromatic assimilation. Chromatic contrast is the shift in the perceived color of a region away from the chromaticity of a nearby inducing color. Chromatic assimilation is the opposite phenomenon, in which color appearance of a region shifts toward the chromaticity of the inducing color. For example, a grid that appears blue shift the appearance of the orange background toward the appearance of the grid (e.g. bluish).
Color assimilation is fundamental to human vision. Little is known about this phenomenon and the neural substrate of color assimilation is perhaps one of the most elusive aspects of human color vision.