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We present the results of a study of the sensitivity of the human visual system (HVS) to spatially varying color stimuli. Sinusoidal grating patterns of different spatial frequencies were presented to six observers and the contrast required to just distinguish the pattern from the surrounding uniform field was determined. Tables and curves of contrast (measured in ΔELab) as a function of frequency were generated at different values of; the orientation (horizontal, vertical and diagonal) of the pattern, the average luminance, the x and y chromaticity co-ordinates, and the direction of the variation of the stimulus in color space (luminance, red-green, and blue-yellow). The results show that the HVS is more sensitive to sinusoidal gratings oriented horizontally and vertically regardless of the type of variation. Furthermore, the HVS is more sensitive to luminance variations than it is to chromatic variations. Tables and curves of the data are presented.
Rajala et al. (Thu,) studied this question.