Impact of Color-Matching Primaries on Observer Matching: Part I – Accuracy

ABSTRACT A good color description starts with the availability of accurate color-matching functions (CMFs) or cone fundamentals (CF). Recent work indicates a discrepancy between visual metamers and those calculated using the standard CIE CMFs or other CMF sets, especially for narrowband sources. In the current study, 54 observers (varying in age, gender, ethnicity, and eye color) performed a series of achromatic color-matching experiments with a 10° stimulus using eight different narrowband primaries under an immersive, perceptually neutral (4673 K) viewing conditions. The reference stimulus was provided by a 70 cd/m2 gray (4613 K) card illuminated by a spectrally broadband light source. The results confirm that substantial and significant differences between experimental and calculated metamers exist, particularly when a short wavelength primary (404 nm) is included and especially for the CIE 1931 2° CMFs. It is found that the primary set characterized by the peak wavelengths 636 nm, 521 nm, and 447 nm, which are close to those of typical RGB primaries widely used in industry, results in the most stable matching performance across all CMF sets. Finally, in addition to the impact of primary wavelength and CMF set, the potential effect of age, gender, ethnicity, and eye color has also been investigated. The effect of age on the color matches is found to be significant and is due to differences in spectral sensitivity of young and old observers with respect to the blue primary; the impact of observer gender, ethnicity, and eye color, on color-matching accuracy is not significant.