Metameric matching and its compensation with individual color matching functions

Abstract

Match in tristimulus values using CIE standard observer is the most popular way to make two colors of different spectral power distributions look identical. This metameric match, however, does not always guarantee those two colors appears the same for individual observer. This may be because the CIE color matching functions (CMFs) are different from those of individual observer. In FVM2003, we showed some individual differences in CMFs. Here, we conducted metameric matching experiments to see whether mismatch in CIE tristimulus values can be explained by compensating individual CMFs. The experiments were conducted on three subjects whose CMFs were measured with our methods. A subject, whose head position was fixed with a chin rest, was asked to make match between a reference and a test stimulus by observing them alternatively and by adjusting color of the test stimulus. Color paper and a CRT monitor were used to present the reference and the test stimulus, respectively. The surrounding of the stimuli was dark. Each subjects conducted 5 to 10 sessions for 7 test colors. The CIE tristimulus values of the test and the reference were different for colors of metameric pairs, and the data showed individual differences. In order to obtain the customized tristimulus values, we applied the individual CMFs to the spectrum of the test and the reference stimuli. Such compensation showed some improvement for several metameric pairs, but not for all pairs. Our results indicate that it is effective to take individual CMFs into consideration for the metameric matching. A part of the results was obtained through the activities of the research group “Evaluating individual color matching functions.”