ready to correct many of the errors in that post. "A range of wavelengths of light stimulates each of these receptor types to varying degrees. Yellowish-green light, for example, stimulates both L and M cones equally strongly, but only stimulates S-cones weakly. Red light, on the other hand, stimulates L cones much more than M cones, and S cones hardly at all; blue-green light stimulates M cones more than L cones, and S cones a bit more strongly, and is also the peak stimulant for rod cells; and violet light stimulates almost exclusively S-cones. The brain combines the information from each type of receptor to give rise to different perceptions of different wavelengths of light." The issue is not so much one wavelength versus more than one wavelength mixed, as it is an assignment of "color" to a combination of cone cell responses, subject to further processing by the brain. Farther along in the Wikipedia article it is noted,
"Chromatic adaptation
"An object may be viewed under various conditions. For example, it may be illuminated by sunlight, the light of a fire, or a harsh electric light. In all of these situations, human vision perceives that the object has the same color: an apple always appears red, whether viewed at night or during the day. On the other hand, a camera with no adjustment for light may register the apple as having varying color."
http://en.wikipedia.org/wiki/Colour_vision
ready to correct many of the errors in that post. "A range of wavelengths of light stimulates each of these receptor types to varying degrees. Yellowish-green light, for example, stimulates both L and M cones equally strongly, but only stimulates S-cones weakly. Red light, on the other hand, stimulates L cones much more than M cones, and S cones hardly at all; blue-green light stimulates M cones more than L cones, and S cones a bit more strongly, and is also the peak stimulant for rod cells; and violet light stimulates almost exclusively S-cones. The brain combines the information from each type of receptor to give rise to different perceptions of different wavelengths of light." The issue is not so much one wavelength versus more than one wavelength mixed, as it is an assignment of "color" to a combination of cone cell responses, subject to further processing by the brain. Farther along in the Wikipedia article it is noted,
"Chromatic adaptation
"An object may be viewed under various conditions. For example, it may be illuminated by sunlight, the light of a fire, or a harsh electric light. In all of these situations, human vision perceives that the object has the same color: an apple always appears red, whether viewed at night or during the day. On the other hand, a camera with no adjustment for light may register the apple as having varying color."