Scotopic luminosity function and color-mixture data.

The hypothesis that rods contribute to color information has not been generally accepted primarily because of the apparent lack of a connection between the scotopic luminosity function and color-mixture data. We present analyses showing that the scotopic luminosity function is intimately related to color data over the entire spectrum, indicating that rods play a central role in normal color vision. These results, not readily explainable in terms of the trichromatic theory, suggest an alternate idea of sensing in terms of the psychophysical quantities called brightness, hue, and saturation.