# How many colors are there?
**URL:** https://boards.straightdope.com/t/how-many-colors-are-there/497480
**Category:** Factual Questions
**Created:** [May 24, 2009, 6:32pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480 "2009-05-24T18:32:49Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Inigo\_Montoya](https://boards.straightdope.com/u/Inigo_Montoya)
#### Post date: [May 24, 2009, 6:32pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/1 "2009-05-24T18:32:49Z")
In the visible spectrum, how many colors, eh? I’m assuming it’s something less than infinite. As I understand the world, sounds are generated in a certain number of cycles per second so that would definitely be a knowable answer. I know light is a bit different (as in ‘totally’) but is this likewise an answerable question?
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### Author:  [@friedo](https://boards.straightdope.com/u/friedo)
#### Post date: [May 24, 2009, 6:40pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/2 "2009-05-24T18:40:45Z")
> [@Inigo\_Montoya](#):
>
> In the visible spectrum, how many colors, eh? I’m assuming it’s something less than infinite. As I understand the world, sounds are generated in a certain number of cycles per second so that would definitely be a knowable answer.
What makes you think that there is a finite number of sound frequencies? 440Hz is different from 440.1Hz which is different from 440.197473Hz, right?
Color is likewise determined by the frequency of electromagnetic waves, with visible light being a relatively tiny portion of the EM spectrum. There are an infinite number of frequencies possible within the visible light range, just like there are an infinite amount of real numbers between 1 and 2.
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### Author:  [@commasense](https://boards.straightdope.com/u/commasense)
#### Post date: [May 24, 2009, 6:43pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/3 "2009-05-24T18:43:26Z")
Both the visible and audible spectra are infinitely divisible, so in terms of objective reality, there is no finite number.
However, if the question becomes, “how many colors can humans distinguish,” that’s probably answerable, although I don’t happen to know.
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### Author:  [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)
#### Post date: [May 24, 2009, 8:00pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/4 "2009-05-24T20:00:49Z")
> [@commasense](#):
>
> Both the visible and audible spectra are infinitely divisible, so in terms of objective reality, there is no finite number.
I would suspect that Planck length constrains the ultimate divisibility of both visible and audible spectra, hence keeping the number well below infinite. No?
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### Author:  [@panache45](https://boards.straightdope.com/u/panache45)
#### Post date: [May 24, 2009, 8:27pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/5 "2009-05-24T20:27:53Z")
> [@Inigo\_Montoya](#):
>
> As I understand the world, sounds are generated in a certain number of cycles per second so that would definitely be a knowable answer
No. That’s like saying there are x number of lengths possible, since we can measure things in inches, kilometers, parsecs, etc.
The only answer is “infinite for both colors and sounds.” But another question would be how many discrete colors or sounds are discernible by humans. The question is probably unanswerable, since the number would vary from one person to another. There are test to determine an individual’s accuity, and the results vary quite a bit.
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### Author:  [@Markxxx](https://boards.straightdope.com/u/Markxxx)
#### Post date: [May 24, 2009, 8:54pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/6 "2009-05-24T20:54:05Z")
I vote for three
Red
Green
Blue
Everything else is a combination of them. Black is a lack of colors
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [May 24, 2009, 8:59pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/7 "2009-05-24T20:59:07Z")
> [@](#):
>
> I would suspect that Planck length constrains the ultimate divisibility of both visible and audible spectra, hence keeping the number well below infinite. No?
Well, maybe. Keep in mind that anything you ever hear about the Planck length (or Planck mass, or Planck time, or whatever) is pure speculation, and based on nothing stronger than back-of-the-envelope estimates to begin with.
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### Author:  [@Quartz](https://boards.straightdope.com/u/Quartz)
#### Post date: [May 24, 2009, 9:19pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/8 "2009-05-24T21:19:43Z")
> [@commasense](#):
>
> However, if the question becomes, “how many colors can humans distinguish,” that’s probably answerable, although I don’t happen to know.
This would be different for different people. Perhaps a better question would be something along the lines of, “How small a difference between colours can a human distinguish?” or, more scientifically, “What is the smallest difference in wavelength of colour that a human can detect?”
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [May 24, 2009, 9:20pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/9 "2009-05-24T21:20:27Z")
> [@panache45](#):
>
> No. That’s like saying there are x number of lengths possible, since we can measure things in inches, kilometers, parsecs, etc.
>
> The only answer is “infinite for both colors and sounds.” But another question would be how many discrete colors or sounds are discernible by humans. The question is probably unanswerable, since the number would vary from one person to another. There are test to determine an individual’s accuity, and the results vary quite a bit.
Assuming for a moment that Planck Lengths and times are a real limit to the granularity of the universe, I think that would have to render attainable frequencies/wavelengths quantised too - and even altering them by doppler-shifting them would only be possible in granular steps (albeit very little ones), because you couldn’t accelerate something by less than 1 Planck length per Planck time squared, or by any non-integer values of the same.
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### Author:  [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)
#### Post date: [May 24, 2009, 9:54pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/10 "2009-05-24T21:54:17Z")
> [@Markxxx](#):
>
> I vote for three
>
> Red
> Green
> Blue
>
> Everything else is a combination of them.
Not quite. There’s a sizable portion of the human-visible colorspace that cannot be reproduced by combining only red, green, and blue light.
On the OP, according to [this paper](http://figment.cse.usf.edu/~sfefilat/data/papers/ThBCT8.39.pdf):
The human eye can accommodate luminance in a single view over a range of about 10,000:1 and is capable of distinguishing about 10,000 colors at a given brightness.
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### Author:  [@yelimS](https://boards.straightdope.com/u/yelimS)
#### Post date: [May 24, 2009, 10:20pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/11 "2009-05-24T22:20:05Z")
isn’t the RGB thing a function of human eyes having “red”, “green” and “blue” cones? (even if **Bytegeist** is right, and RGB is only an approximation, though a good one)
if that’s how it works, i suppose there could be an animal with super vision and five hundred different cones, who’d need a palette of five hundred primary colours to paint.
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### Author:  [@Arkcon](https://boards.straightdope.com/u/Arkcon)
#### Post date: [May 24, 2009, 10:40pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/12 "2009-05-24T22:40:05Z")
> [@Quartz](#):
>
> This would be different for different people. Perhaps a better question would be something along the lines of, “How small a difference between colours can a human distinguish?” or, more scientifically, “What is the smallest difference in wavelength of colour that a human can detect?”
Within that line of reasoning, I’d heard, back in the day, that 16 bit color depth was “True Color”, and the number of individual pixel values possible was greater than what the human eye could discern. 'Course, now we have 32-bit color, and \*that’s \* called “True Color”, 16-bit is now demoted to “High Color”, at least on my system. So I’m guessing manufacturers will always claim to redefine it – a quick Wikipedia says that 40-bit and 60-bit color is available.
> **[Color depth](https://en.wikipedia.org/wiki/Color_depth#32-bit_color)**
>
> Color depth, also known as bit depth, is either the number of bits used to indicate the color of a single pixel, or the number of bits used for each color component of a single pixel. When referring to a pixel, the concept can be defined as bits per pixel (bpp). When referring to a color component, the concept can be defined as bits per component, bits per channel, bits per color (all three abbreviated bpc), and also bits per pixel component, bits per color channel or bits per sample. Mo Color ...
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### Author:  [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)
#### Post date: [May 24, 2009, 10:45pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/13 "2009-05-24T22:45:28Z")
> [@yelimS](#):
>
> (even if **Bytegeist** is right, … )
Hey. It can happen.
> [@](#):
>
> isn’t the RGB thing a function of human eyes having “red”, “green” and “blue” cones?
Exactly.
> [@](#):
>
> if that’s how it works, i suppose there could be an animal with super vision and five hundred different cones, who’d need a palette of five hundred primary colours to paint.
Five hundred you won’t find, but [four](http://www.webexhibits.org/causesofcolor/17B.html) (not four hundred though) certainly exists, in the birds.
Scientists suspect this might be the reason birds don’t seem to enjoy television.
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### Author:  [@Napier](https://boards.straightdope.com/u/Napier)
#### Post date: [May 24, 2009, 10:51pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/14 "2009-05-24T22:51:49Z")
> [@yelimS](#):
>
> isn’t the RGB thing a function of human eyes having “red”, “green” and “blue” cones? (even if **Bytegeist** is right, and RGB is only an approximation, though a good one)
> if that’s how it works, i suppose there could be an animal with super vision and five hundred different cones, who’d need a palette of five hundred primary colours to paint.
They do refer to the three kinds of cones as red, blue, and green sometimes, but it isn’t accurate for this discussion. The cones are all sensitive to all the wavelengths, but the profiles of their sensitivities over the range of wavelengths is very different. It would be better to imagine three kinds of tinted glass that are reddish and greenish and bluish in hue, and then you hold a lightmeter behind each of them in turn to estimate the color of whatever is in front of them.
Another point, about this conversation in general: “color” can mean the color of light or the color of an object. When it is the color of light, it is a well defined idea. However, when it is the color of an object, which is how we usually use it, the way our eyes perceive it is much more complicated, because the light we get depends on the object and the light that illuminated it. In any case, though, “color” does not suggest a wavelength, but rather our perception of some mixture of all the wavelengths. That isn’t very precise, either, because it sounds like there are a finite number of them. Imagine a graphed curve showing a potentially different height on the vertical brightness axis for each location on the horizontal wavelength axis, and combine all the contribution along the wavelength axis under that curve. So our perception of an integrated function over wavelength. Our perception is driven largely by the ratio of the response we get from each of our tinted-glass-like cone subsystem. First we take the ratio of the bluish receptors to the sum of the reddish and greenish ones, and then we take the ratio of the reddish to greenish, and those two values together we consider the chromaticity or, briefly, the color.
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### Author:  [@Dog80](https://boards.straightdope.com/u/Dog80)
#### Post date: [May 24, 2009, 10:58pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/15 "2009-05-24T22:58:11Z")
> [@Inigo\_Montoya](#):
>
> **How many colors are there?**
Over nine thousand.
d&r
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [May 24, 2009, 10:59pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/16 "2009-05-24T22:59:12Z")
Quoth **Mangetout** :
> [@](#):
>
> because you couldn’t accelerate something by less than 1 Planck length per Planck time squared, or by any non-integer values of the same.
For all the more we know about anything relating to the Planck scale, this at least we know is false. The Planck acceleration is in fact a ludicrously _large_ acceleration, such that all known accelerations in the Universe are significantly smaller than it. So you could in fact Doppler shift your quantized frequencies by any amount you choose.
This might begin to give some appreciation for why it’s so hard to construct models of physics with quantized time and space.
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### Author:  [@sailor](https://boards.straightdope.com/u/sailor)
#### Post date: [May 24, 2009, 11:31pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/17 "2009-05-24T23:31:33Z")
> [@Markxxx](#):
>
> I vote for three
>
> Red
> Green
> Blue
>
> Everything else is a combination of them. Black is a lack of colors
I vote for: Dark red, light red, Dark blue, light blue, dark green, light green, black, white, and burgundy with a slight avocado tint.
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### Author:  [@chrisk](https://boards.straightdope.com/u/chrisk)
#### Post date: [May 24, 2009, 11:40pm UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/18 "2009-05-24T23:40:21Z")
> [@Bytegeist](#):
>
> Not quite. There’s a sizable portion of the human-visible colorspace that cannot be reproduced by combining only red, green, and blue light.
Can you cite me on this one? I would think that if you pick your red, green, and blue wavelengths appropriately, and have absolute control over how much of each you produce, from 0 up to infinite intensity, you could reproduce just about anything in terms of human eyes would see it.
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### Author:  [@ChrisBooth12](https://boards.straightdope.com/u/ChrisBooth12)
#### Post date: [May 25, 2009, 12:02am UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/19 "2009-05-25T00:02:47Z")
> [@chrisk](#):
>
> Can you cite me on this one? I would think that if you pick your red, green, and blue wavelengths appropriately, and have absolute control over how much of each you produce, from 0 up to infinite intensity, you could reproduce just about anything in terms of human eyes would see it.
I used to work in printing and their were some colors that we could not make using our CYMK system.
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### Author:  [@sailor](https://boards.straightdope.com/u/sailor)
#### Post date: [May 25, 2009, 12:21am UTC](https://boards.straightdope.com/t/how-many-colors-are-there/497480/20 "2009-05-25T00:21:59Z")
> [@chrisk](#):
>
> Can you cite me on this one? I would think that if you pick your red, green, and blue wavelengths appropriately, and have absolute control over how much of each you produce, from 0 up to infinite intensity, you could reproduce just about anything in terms of human eyes would see it.
the keywords to search for are color & gamut.
Check out [File:CIExy1931 sRGB.svg - Wikimedia Commons](http://commons.wikimedia.org/wiki/File:CIExy1931_sRGB.svg)
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