Editing Cone cell (section)

===Classes===
Most vertebrates have several different classes of cone cells, differentiated primarily by the specific [[photopsin]] expressed within. The number of cone classes determines the degree of [[color vision]]. Vertebrates with one, two, three or four classes of cones possess [[monochromacy]], [[dichromacy]], [[trichromacy]] and [[tetrachromacy]], respectively.

Humans normally have three classes of cones, designated '''L''', '''M''' and '''S''' for the long, medium and short wavelengths of the visible spectrum to which they are most sensitive.<ref>{{Cite journal |last=Roorda |first=A. |last2=Williams |first2=D. R. |date=1999-02-11 |title=The arrangement of the three cone classes in the living human eye |url=https://pubmed.ncbi.nlm.nih.gov/10028967/ |journal=Nature |volume=397 |issue=6719 |pages=520–522 |doi=10.1038/17383 |issn=0028-0836 |pmid=10028967}}</ref> L cones respond most strongly to light of the longer red [[Wavelength|wavelengths]], peaking at about {{val|560|u=nm}}. M cones, respond most strongly to yellow to green medium-wavelength light, peaking at {{val|530|u=nm}}. S cones respond most strongly to blue short-wavelength light, peaking at {{val|420|u=nm}}, and make up only around 2% of the cones in the human retina. The peak wavelengths of L, M, and S cones occur in the ranges of {{val|564|-|580|u=nm}}, {{val|534|-|545|u=nm}}, and {{val|420|-|440|u=nm}} nm, respectively, depending on the individual.{{cn|date=January 2025}} The typical human photopsins are coded for by the genes [[OPN1LW]], [[OPN1MW]], and [[OPN1SW]]. The [[CIE 1931 color space]] is an often-used model of spectral sensitivities of the three cells of a typical human.<ref name="Wyszecki">{{cite book |last=Wyszecki |first=Günther |url=https://archive.org/details/colorscienceconc00unse |title=Color Science: Concepts and Methods, Quantitative Data and Formulae |author2=Stiles, W.S. |publisher=Wiley Series in Pure and Applied Optics |year=1981 |isbn=978-0-471-02106-3 |edition=2nd |location=New York |url-access=registration}}</ref><ref>{{cite book |author=R. W. G. Hunt |url=https://archive.org/details/reproductionofco0000hunt/page/11 |title=The Reproduction of Colour |publisher=Wiley–IS&T Series in Imaging Science and Technology |year=2004 |isbn=978-0-470-02425-6 |edition=6th |location=Chichester UK |pages=[https://archive.org/details/reproductionofco0000hunt/page/11 11–12] |url-access=registration}}</ref>