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:
“A physician’s physiology has much the same relation to his power of healing as a cleric’s divinity has to his power of influencing conduct.”
—Samuel Butler (1835–1902)
“‘Twas mercy brought me from my Pagan land,
Taught my benighted soul to understand
That there’s a God, that there’s a Saviour too:
Once I redemption neither sought nor knew.
Some view our sable race with scornful eye,
“Their color is a diabolic die.”
Remember, Christians, Negroes, black as Cain,
May be refin’d, and join th’ angelic train.”
—Phillis Wheatley (c. 1753–1784)
“Only by being guilty of Folly does mortal man in many cases arrive at the perception of Sense. A thought which should forever free us from hasty imprecations upon our ever-recurring intervals of Folly; since though Folly be our teacher, Sense is the lesson she teaches; since, if Folly wholly depart from us, Further Sense will be her companion in the flight, and we will be left standing midway in wisdom.”
—Herman Melville (1819–1891)