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This article has been classified as relating to the physiology of the brain, nerves and nervous system.

This Page Is Lying About Human Vision[edit]

Men only have one, or two cones, not three, from only having one X chromosome (which only gives one, or two cones). So, how is it normal for humans to be trichromatic? Normal human vision is from TWO cones, not three, for both genders. To be either trichromatic, or tetrachromatic requires having two X chromosomes that carry different cone DNA from eachother, resulting in three, or four different cones instead of the usual two. Even most women do not have trichromacy, let alone tetrachromacy. Yet, someone is claiming on this page that normal human vision is trichromacy. Someone needsto do proper research, restricting it to modern science, ignoring random bloggers and other unqualified sources, and redo the page. -- (talk) 18:31, 15 November 2017 (UTC)

Just to be clear on this, are you claiming that humans are not trichromats? Andy Dingley (talk) 19:02, 15 November 2017 (UTC)

Color response plot misleading[edit]

I believe this plot is misleading in two ways:

First, it claims to be adapted from Stockman et al. Vol. 10, No. 12/December 1993/J. Opt. Soc. Am. A 2491). However, it would appear the adaptation was not sufficiently careful, as it missed the UV behavior, see figure 12 in above reference.

Second, and more importantly, it does not accurately reflect reality, and fails to account for the following phenomena: We know the shortest wavelength on the rainbow appears purple, as does and equal combination of red + blue (RGB 128,0,128). This is inconsistent with the above plot.

Instead, see discussion on StackExchange. The correct plot should be, which is referenced to Bowmaker, J.K., & Dartnall, H.J.A. Visual pigments of rods and cones in a human retina. Journal of Physiology, 298, 1980, 501-511 figure 2, as it allows us to understand how an RGB-based screen can generate a color which appears as purple. — Preceding unsigned comment added by Shai mach (talkcontribs) 08:54, 6 December 2015 (UTC)


It seems as though there should be a single article on 'chromacy' or something like that, and that trichromat, tetrachromat, and dichromat should be stubs linking to it.

Color vision. However, that article would get quite unwieldly if everything from the five -chromat articles were shoved into it. On my "to do once my DSL is back" list is refactoring this series of articles. IceKarma 17:04, 2005 Jun 6 (UTC)
I agree with IceKarma. Besides, the word "chromacy" barely exists whereas trichromacy etc are in common use - so we'd end up with an unhealthy mass of redirects. seglea 23:29, 6 Jun 2005 (UTC)

The definition "A trichromat is an organism for which the perceptual effect of any arbitrarily chosen light from its visible spectrum can be matched by a mixture of no more than three different pure spectral lights" is patently incorrect.

If that were in fact the case, an RGB color space would be capable of representing all colors humans can perceive -- and this is well-known to be impossible. "Trichromat" refers to the fact that we have three different color receptors, not to the (incorrect) belief that our entire range of color vision can be duplicated with three primaries. The reason for the mismatch is that there is significant overlap in the sensitivities of our color receptors, so that for example the "green" primary color we use in imaging also significantly stimulates the red color receptor. To represent all colors using exactly three wavelengths of light, you would have to find three wavelengths which stimulate one and only one kind of color receptor -- and, at least in human color vision, they don't exist. Egomaniac 06:58, 7 July 2006 (UTC)

I've gone back added a factual accuracy warning regarding this issue.Egomaniac 17:45, 13 September 2006 (UTC)

Opening sentence[edit]

What does that really mean? It doesn't seem to make much sense to a layman like me. And all the -chromat articles use a copy of it. 02:14, 9 August 2006 (UTC)


Could this article merge from Trichromatic color vision? They seem to cover the same topic from different perspectives. --Quiddity 03:57, 31 August 2006 (UTC)

Yes, they should be. Both are too short, anyway. Mr. Toad 01:41, 4 May 2007 (UTC)
Yep. go ahead and merge them :). --jacobolus (t) 11:13, 9 May 2007 (UTC)

I concur. Anyone up for it? Dicklyon 00:06, 26 June 2007 (UTC)

I think maybe this article should also be merged with Young–Helmholtz theory. Don't have time now, but might be able to later.. Mmhrmhrm (talk) —Preceding undated comment added 13:33, 30 August 2012 (UTC)

Male monkeys[edit]

From the article: "Humans and other closely related primates are usually trichromats, as are female New World monkeys" (emp. added)

I find this statement intriguing. Is there more information as to why it is only the females? What are the males (dichromats, I assume)? - This particular article is probably not the place for this information, but it would be good to have a link/cross reference to another article discussing it. -- (talk) 18:51, 29 July 2008 (UTC)

Old refs[edit]

I moved some refs to an appropriate place, based on my inference from this edit. Dicklyon (talk) 02:36, 2 December 2008 (UTC)

one million?[edit]

(1) Thus, interactions between at least two types of cone is necessary to produce the ability to perceive color. With at least two types of cones, the brain can compare the signals from each type and determine both the intensity and color of the light.

(2) It is estimated that each of the three cone types in the human retina can pick up about 100 different gradations, and that the brain can combine those variations such that the average human can distinguish about one million different colors.

Well, 100*100*100 = one million. But (1) indicates, that brains are interested in difference of cones, not the cones themselves. If there are two comparison signals (from cones to brains), S-M and M-L, then that calculation doesn't match. Thus, what is the truth? — Preceding unsigned comment added by Tie don port aat (talkcontribs) 14:41, 6 January 2011 (UTC)

I think some undocumented information here is wrong[edit]

I believe this statement is wrong: "Since the likelihood of response of a given cone varies not only with the wavelength of the light that hits it but also with its intensity, the brain would not be able to discriminate different colors if it had input from only one type of cone. Thus, interaction between at least two types of cone is necessary to produce the ability to perceive color." If that were the case, then lasers lasers should only have color if they excite more than one kind of cone. This might be true for those that are red, yellow, or green, and even some that are greenish blue. But the lasers that have short wavelength blue light should appear not to be blue. ghh 16:25, 29 June 2012 (UTC) — Preceding unsigned comment added by George H. Harvey (talkcontribs)

Making Changes[edit]

Hey all, I'll be starting to make some major editing changes and adding information to this article. My proposed changes will be documented here, so feel free to provide some input as I go along. Pcoutu (talk) 16:11, 21 February 2013 (UTC)

External links modified[edit]

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