von Kries Coefficient Law Applied to Subjective Color Change Induced by Background Color

Quantitative prediction of subjective color change induced by a chromatic background has been developed, based on the von Kries coefficient law, and tested by experiment. The presupposed viewing condition is to make a color match between two small target colors placed in the centers of two adjacent chromatic backgrounds. The state of adaptation of the eyes observing the target T1 is mostly determined by the immediate background B1 but there is some contribution of the background B2. Assume that the effect of the immediate background on the adaptation is n times greater than the effect of the other; then, based on the von Kries coefficient law, the sensitivity of the eye to one of the three fundamental responses R is inversely proportional to nRB1+RB2, where RB1 and RB2 are the fundamental responses to the backgrounds 1 and 2. The same considerations can be applied when the target 2 is observed; then RT1/(nRB1+RB2)=RT2/(nRB2+RB1),where RT1 and RT2 are the fundamental responses of T1 and T2. From the equation, from RB1, RB2 and RT1 and an assumed weight factor n, the fundamental response RT2 of the T2 that matches T1 on the different chromatic background can be estimated. The prediction was tested by observation and it was found that weight factors ranging from 1.2 to 1.6 gave reasonable predictions. Two kinds of minor adjustments were applied to the basic predictions; the prediction was improved by the adjustments.