[A simple description of color adaptation in the red-green system]

The red/green-system is examined experimentally under adaptation to green and to magenta. The theoretical basis consists of Grassmann's laws and of a new linear opponent colors theory. Besides brightness, this opponent colors theory specifies the two chromatic axes yellow-blue and green-magenta within color space. An axiom is formulated for the description of color adaptation for the red/green-system. Two pairs of color vectors are assumed to be equivalent with respect to the red/green-system if the quotients of the respective red/green-coordinates of test vector and adaptation vector are identical. For both vectors the control of the other two opponent colors systems is presupposed. The axiom is tested for four green and four magenta adaptation vectors. Three observers take part in the experiment. For each observer an individual plane of constant brightness and his or her individual opponent colors axes are estimated experimentally. For both magenta and green adaptation the data agree well with the theoretical predictions. Thus they provide empirical support for the axiom. For the red/green-system color adaptation can be described very simply if the other two opponent colors systems are controlled.