Physiology of Color Perception
Perception of color begins with specialized retinal cells containing pigments with different spectral sensitivities, known as cone cells. In humans, there are three types of cones sensitive to three different spectra, resulting in trichromatic color vision.
Each individual cone contains pigments composed of opsin apoprotein, which is covalently linked to either 11-cis-hydroretinal or more rarely 11-cis-dehydroretinal.
The cones are conventionally labeled according to the ordering of the wavelengths of the peaks of their spectral sensitivities: short (S), medium (M), and long (L) cone types. These three types do not correspond well to particular colors as we know them. Rather, the perception of color is achieved by a complex process that starts with the differential output of these cells in the retina and it will be finalized in the visual cortex and associative areas of the brain.
For example, while the L cones have been referred to simply as red receptors, microspectrophotometry has shown that their peak sensitivity is in the greenish-yellow region of the spectrum. Similarly, the S- and M-cones do not directly correspond to blue and green, although they are often depicted as such. It is important to note that the RGB color model is merely a convenient means for representing color, and is not directly based on the types of cones in the human eye.
The peak response of human cone cells varies, even among individuals with 'normal' color vision; in some non-human species this polymorphic variation is even greater, and it may well be adaptive.
Read more about this topic: Color Vision
Famous quotes containing the words physiology, color and/or perception:
“I have more in common with a Mexican man than with a white woman.... This opinion ... chagrins women who sincerely believe our female physiology unequivocally binds all women throughout the world, despite the compounded social prejudices that daily affect us all in different ways. Although women everywhere experience life differently from men everywhere, white women are members of a race that has proclaimed itself globally superior for hundreds of years.”
—Ana Castillo (b. 1953)
“Rain falls into the open eyes of the dead
Again again with its pointless sound
When the moon finds them they are the color of everything”
—William Stanley Merwin (b. 1927)
“No one has ever seen a Republican mass meeting that was devoid of the perception of the ludicrous.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)