ABSTRACT
In natural viewing, nearly all colors that we experience are seen within a context of surrounding light and nearby objects, and this context affects color appearance. The change in color appearance caused by surrounding light is called ‘chromatic induction’. There are two types of induction: chromatic contrast and chromatic assimilation. Chromatic contrast is the shift in appearance of the test field away from the chromaticity of the inducing (surrounding) color. For example, a light that appears yellow in isolation will appear greenish-yellow when surrounded by a light that appears red. Chromatic assimilation is the opposite phenomenon, in which the appearance of a test field shifts toward the chromaticity of the inducing color. For example, a grid that appears blue may shift the appearance of an orange background toward the appearance of the grid (e.g. bluish). Chromatic contrast has dominated the vision literature on induction, while chromatic assimilation has received less attention. However, assimilation probably occurs at least as frequently as contrast. De Valois and De Valois (1988) stated that assimilation is by far the more important phenomenon because assimilation is the rule in color interactions while chromatic contrast is relatively rare. De Weert (1991) made clear how assimilation can influence perception in our natural environment such as when the perceived color of bricks depends on whether they are observed with or without mortar.
