# How many colors can the human eye see? **URL:** \ **Category:** Factual Questions\ **Created:** [November 9, 2000, 6:04am UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421 "2000-11-09T06:04:19Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [November 13, 2000, 5:38pm UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/21 "2000-11-13T17:38:22Z")
> [@](#): > > \*Originally posted by Lexicon \* > \*\*This an excellent discussion, and thank you for all the information. I will have to look into this more deeply. > > I would like to tell you all why I asked. It was not just random curiosity. I don’t spend too much time in GQ, so many of you may not know me. I work in the technical field, and I always wondered why computer graphics cards went as high as 32-bit color when > > A) I always thought many monitors were not capable of this > > and > > B) Many of my peers have said that “The human eye can’t perceive more than 16-bit color anyway” > > It would seem, according to the information provided by Pochacco that the former may be correct and the latter may be erroneous. In any case, I thought it may help me get the answer I am looking for if I narrow the scope of my query. > > \*\* 1. As Punoqllads points out, both 24- and 32-bit color use the same number of bits (8) to represent RGB. 32-bit color uses the extra byte to represent transparency. It also means that the pixel data is aligned on long word boundaries which makes for faster memory access on some machines. The bottom line is that there’s no visual difference between 24- and 32- bit color. But as Punoqllads also points out monitors can indeed handle 32-bit color. 2. Well, _I_ can tell the difference between 16- and 32-bit color, but then I spent many years worrying about it! For most people most of the time 16-bit color is more than adequate for the job. Unless you’re doing actual graphics work on your computer, there’s probably no need to have it see to “True Color”. ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [November 13, 2000, 5:53pm UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/22 "2000-11-13T17:53:48Z")
> [@](#): > > \*Originally posted by yabob \* > \*\* Any idea what those response curves look like? Are they identical curves except for having maxima at different frequencies? Since some sort of chemical-based response is involved, I could imagine that this is not true. Is receptor response for a particular primary significantly narrower or broader? > \*\* The data I’ve seen show the response curves looking very much like normal distributions (bell curves)centered on particular wavelengths. The red and the green response curves overlap substantially. The blue response curve is off by itself at the high end of the spectrum, but is much, much weaker. ---
**Author:** ![Kyberneticist](https://avatars.discourse-cdn.com/v4/letter/k/dc4da7/32.png) [@Kyberneticist](https://boards.straightdope.com/u/Kyberneticist)\ **Post date:** [November 13, 2000, 7:30pm UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/23 "2000-11-13T19:30:52Z")
This seems like an excellent opportunity to get a question answered. Is it possible that a small number of people can perceive the weak radiation emitted by a hot human body? Or some that can perceive the more energetic wavelengths and be able to distinguish between seemingly identically colored objects? (see the patterns on flowers that they use to attract bees, for example) There are animals that perceive these wavelengths right? Is there any reason why humans could not develop the ability, or at least add the appropriate genes? ---
**Author:** ![Punoqllads](https://avatars.discourse-cdn.com/v4/letter/p/d2c977/32.png) [@Punoqllads](https://boards.straightdope.com/u/Punoqllads)\ **Post date:** [November 13, 2000, 8:41pm UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/24 "2000-11-13T20:41:21Z")
> [@](#): > > \*Originally posted by Kyberneticist \* > \*\*This seems like an excellent opportunity to get a question answered. > Is it possible that a small number of people can perceive the weak radiation emitted by a hot human body? Or some that can perceive the more energetic wavelengths and be able to distinguish between seemingly identically colored objects? (see the patterns on flowers that they use to attract bees, for example) > There are animals that perceive these wavelengths right? Is there any reason why humans could not develop the ability, or at least add the appropriate genes? \*\* Actually, the human retina can see light in the near-ultraviolet. However, the retina is also damaged by this light, so the cornea has evolved to absorb it. I don’t know about near-infrared, though. The human body would produce radiation primarily with wavelengths in the far-infrared, so I’m not sure if any animal would be able to perceive this. Why we don’t see further in the spectrum, I guess, is that we don’t really need to. The human eye is marvelously adapted to being precisely as powerful as we needed it as hunter-gatherers, using as few resources as possible. ---
**Author:** ![don\_willard](https://avatars.discourse-cdn.com/v4/letter/d/a88e57/32.png) [@don\_willard](https://boards.straightdope.com/u/don_willard)\ **Post date:** [November 13, 2000, 9:32pm UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/25 "2000-11-13T21:32:36Z")
All I know is that there was an excellent program known by the name of Paintbrush but when the boss updated my computer to Windows 95 it had Paint instead, an inferior program because it 1) reversed color unpredictably and inconsistently, 2) would not shrink and grow. You have to pull on margins or corners instead, but Paintbrush’s shrink and grow you just had to select an image and it would shrink or grow to whatever size you then boxed, 3) the Paint program lacks those colors that are made up of two other colors, which Paintbrush had and which enabled all sorts of interesting effects on shrink and grow 4) There is no way to enlarge on Paint. I always enlarged on Paintbrush. I e-mailed Microsoft about this but they just thanked me for sending it in. People tell me there are lots of graphics programs but I did a lot with Paintbrush in mathematical drawings and many other artistic ones, and now Microsoft has ruined it. Although the local lady who deals with computers was able to put back my old Paintbrush on Windows 95, she says she doesn’t know if she can get it put on when the boss so-called updates (which alwayhs makes things worse) around here by installing all new computers (the actual machines). Signed, Depressed about Technology ---
**Author:** ![Kyberneticist](https://avatars.discourse-cdn.com/v4/letter/k/dc4da7/32.png) [@Kyberneticist](https://boards.straightdope.com/u/Kyberneticist)\ **Post date:** [November 13, 2000, 9:39pm UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/26 "2000-11-13T21:39:19Z")
Ah. near infrared vs far. I didn’t want to just say infrared since I was certain it would get confused. What I want is cool Predator style heat vision (but not a pathetic type that gets confused by a layer of drying mud). Actually pit vipers do sense body heat, although perhaps these primitive sensors shouldn’t qualify as eyes. Also, since their body temperature is much lower then that of their prey they avoid being blinded by their own body heat. Maybe our infrared sensitive eyes could be insulated somehow from the rest of the body… In any case, definitely not a trivial modification to human structure. Guess I’ll have to stick with low-light and infrared night vision goggles… ---
**Author:** ![Silo](https://avatars.discourse-cdn.com/v4/letter/s/ac91a4/32.png) [@Silo](https://boards.straightdope.com/u/Silo)\ **Post date:** [November 13, 2000, 11:00pm UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/27 "2000-11-13T23:00:56Z")
> [@](#): > > I just want to know reliably how many colors the average human eye can see. The human eye can discriminate 7 million colors. (This is the currently accepted figure.) ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [November 13, 2000, 11:20pm UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/28 "2000-11-13T23:20:30Z")
> [@](#): > > \*Originally posted by Kyberneticist \* > \*\*This seems like an excellent opportunity to get a question answered. > Is it possible that a small number of people can perceive the weak radiation emitted by a hot human body? Or some that can perceive the more energetic wavelengths and be able to distinguish between seemingly identically colored objects? (see the patterns on flowers that they use to attract bees, for example) > There are animals that perceive these wavelengths right? Is there any reason why humans could not develop the ability, or at least add the appropriate genes? \*\* You certainly couldn’t train yourself to do it. The response curves are hardcoded by the pigments in the cones in your eye. I’ve read some articles that suggest that pigment variations between individuals can shift the peak wavelengths of the response curves by 4 or 5 nanometers but nothing that would move your receptors way outside the normal spectrum of human vision (400 to 700 nanometers). If you’re talking theoretically plausible near-future genetic engineering – maybe. You could figure out the sequence that codes the pigment protein and replace it, but you’d still have to deal with the damaging effects of UV light. And if you went too far out of the visual range you’d have trouble forming an image – when different wavelengths pass through a lens they focus at different distances. If your spectral distribution is too large it’s impossible to keep everything in focus simultaneously. ---
**Author:** ![Lexicon](https://avatars.discourse-cdn.com/v4/letter/l/ac8455/32.png) [@Lexicon](https://boards.straightdope.com/u/Lexicon)\ **Post date:** [November 14, 2000, 2:12am UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/29 "2000-11-14T02:12:22Z")
Originally posted by Silo > [@](#): > > The human eye can discriminate 7 million colors. (This is the currently accepted figure.) Can anyone back this up? Don’t get me wrong, Silo is a smart guy and all that, but I would like to see some hard facts or a cite or something like that so I can know this is a pretty accurate bit of info, so I don’t look like a buffoon (any more so than usual, at least) if it ever comes up in discussion. …I get into a lot of intellectual discussions. Most of the time I just listen, unless it’s about something I know a lot about, like navel lint or dust. So I understandably always want to learn stuff like this so I can participate more often. ---
**Author:** ![Silo](https://avatars.discourse-cdn.com/v4/letter/s/ac91a4/32.png) [@Silo](https://boards.straightdope.com/u/Silo)\ **Post date:** [November 14, 2000, 3:33am UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/30 "2000-11-14T03:33:31Z")
well this site says 8 million: [http://www.grolaser.com/laservisioncorrection/patienteducation/colorvision.html](http://www.grolaser.com/laservisioncorrection/patienteducation/colorvision.html) others I went to said 6.5, and 7.5 mil. I remember hearing 7 mill was the current accepted figure from my psych teacher. oh well… ---
**Author:** ![Lexicon](https://avatars.discourse-cdn.com/v4/letter/l/ac8455/32.png) [@Lexicon](https://boards.straightdope.com/u/Lexicon)\ **Post date:** [November 14, 2000, 5:36am UTC](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421/31 "2000-11-14T05:36:14Z")
Thanks for the link. You da man. It says that we can see 8,000 colors in almost 8 million shades and tints. So how many colors, total, does that mean? Is it simple math, meaning that we can see 64 billion colors? Or is there more to it? 64 billion? That seems like a lot. Too many in fact, but it’s from Silo’s link, so it seems reputable. Who knows. Maybe it’s not a question that can have cut and dried answer. [Previous page](https://boards.straightdope.com/t/how-many-colors-can-the-human-eye-see/40421.md?page=1)