Chromaticity discrimination: effects of luminance contrast and spatial frequency

We examined the effects of luminance contrast and spatial frequency on chromaticity discrimination of grating bars. Alternate bars of gratings were filled with light of a standard wavelength and light that could be varied in wavelength. The observer set the variable bars to match the standard bars in hue. Discrimination, as measured by the standard deviation of the matches, decreased as spatial frequency increased. Luminance contrast did not improve chromaticity discrimination but did lead to Bezold-Brücke hue shifts that were spatial-frequency dependent.