Color-mixture functions with a white desaturant

Abstract

Color mixture functions were obtained (a) with the traditional method of using one of the three primaries to desaturate the test wavelength, and (b) by desaturating with a broadband white light. Three normal trichromats made monocular, foveal color matches to wavenumbers from 2300 to 1500/mm in 50/mm increments using primaries of 2177/mm (459.3 mu), 1900 (526.3), and 1550 (645.2), with a 2 degree field at a luminance of about 1.0 mL. The most prominent differences were that the amounts of all three primaries needed to match test stimuli below the blue primary (2200-2300/mm) were less with the white desaturant, as was the negative-red lobe between the blue and green primaries. The dominant wavelengths of the test stimuli at the match points were compared for the two conditions, and comparisons were made between the changes under these conditions and the differences in the CIE 2 deg. and 10 deg. CMFs, foveal and parafoveal CMFs, and changes resulting from reduction in luminance.