A new chromatic-adaptation model is proposed based on a law of coefficients was proposed by him 1 in the early twentieth century. His hypothesis assumes that to determine corresponding fundamental tristimulus values that elicit the same colour appearance over changes the visual mechanism has three fundamental sensitivity processes, which stay invariable in relative spectral distri-in illumination conditions. Integrating several hypotheses put forward by earlier researchers such as the linear: bution, and, as the spectral quality of illumination changes, the fundamental sensitivities are in inverse pro-von Kries and Helson et al.; the nonhomogeneous and linear: Burnham et al.; the nonlinear: MacAdam, Hunt, portion to the strength of the illuminant. The amounts of the three fundamental sensitivities change with the three Bartleson, BFD, RLAB, LLAB and so on, the new model emerges as a nonhomogeneous, linear model incorporat-coefficients, that is, the von Kries coefficients. It implies that the hypothesis would lead under certain conditions ing von Kries coefficients with nonlinearities. No covert information is required beyond a knowledge of the tristim-not only to symmetric matching but also to asymmetric matching, which is linear and transitive. Hence, the von ulus values of samples and illuminants. To compare the performance of this model with those of other currently Kries's coefficient rule may be represented in terms of fundamental tristimulus values as follows: available transformation methods, the corresponding-colours data from four independent studies of chromatic R ร
aR, adaptation are used. The results indicate that the new model agrees well with the four sets of data used. The G ร
bG,
(1) new model gives more accurate prediction to these data than the others tested. Hence, it is obvious that the pro-B ร
gB, posed model can give accuracy as well as generality and simplicity. The new nonhomogeneous, linear model is where a, b, g are the von Kries coefficients that are supposed to depend on the surround and pre-exposure more suitable for chromatic adaptation than the others tested, at least for the four independent sets of experimen-stimuli in various adaptation situations. In practice, a common problem still exists, that is, de-tal data employed.