The contrast sensitivity of human colour vision to red‐green and blue‐yellow chromatic gratings.

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Abstract
A method of producing red-green and blue-yellow sinusoidal chromatic gratings is used which permits the correction of all chromatic aberrations. A quantitative criterion is adopted to choose the intensity match of the 2 colors in the stimulus: this is the intensity ratio at which contrast sensitivity for the chromatic grating differs most from the contrast sensitivity for a monochromatic luminance grating. This intensity match varies with spatial frequency and does not necessarily correspond to a luminance match between the colors. Contrast sensitivities to the chromatic gratings at the criterion intensity match are measured as a function of spatial frequency, using field sizes ranging from 2-23.degree.. Both blue-yellow and red-green contrast sensitivity functions have similar low-pass characteristics, with no low-frequency attenuation even at low frequencies below 0.1 cycles/deg. The limiting acuities based on red-green and blue-yellow color discriminations are similar at 11 or 12 cycles/deg. Comparisons between contrast sensitivity functions for the chromatic and monochromatic gratings are made at the same mean luminances. At low spatial frequencies below 0.5 cycles/deg, contrast sensitivity is greater to the chromatic gratings, consisting of 2 monochromatic gratings added in antiphase, than to either monochromatic grating alone. Above 0.5 cycles/deg, contrast sensitivity is greater to monochromatic than to chromatic gratings.