<p>Trichromatic color system is based on using 3 carefully selected reference spectral power distributions(SPD) as you imagine. CIE uses its own reference SPDs, but there are others who prefer using other SPDs as reference. So the answer to the question</p>
<blockquote>
<p>Are the actual wavelengths of sRGB RGB primaries defined and if so what are they in nanometers?</p>
</blockquote>
<p>differs, or might differ, with respect to institutions. As for trustworthy resources:</p>
<p>Scott Burns had kindly provided some reference SPDs in his <a href="http://scottburns.us/fast-rgb-to-spectrum-conversion-for-reflectances/" rel="nofollow noreferrer">website</a>.</p>
<p>For illuminants and observers etc. you can check the <a href="https://www.rit.edu/cos/colorscience/rc_useful_data.php" rel="nofollow noreferrer">website</a> of Munsell Color Science Lab.</p>

CC BY-SA 4.0
2021-01-08T08:45:25.570Z
Thank you. This is exactly what I was looking for. It will be interesting to compare the SPDs of primaries of real monitors with this if I ever manage to make the spectrometer.
Martynas Žiemys
CC BY-SA 4.0
2021-01-08T00:17:45.667Z
2021-01-08T22:16:00.737Z
2021-01-08T22:16:00.737Z
Kaan E.
<p>The primaries of sRGB are not pure wavelengths, they are color mixtures. Their true definition is in terms of CIE chromaticity coordinates. That said, for sRGB, the red primary is close-ish to 610nm, green is very roughly 555nm, and blue is close-ish to 465nm.</p>
<p>The Rec. 2020 RGB space, by the way, is actually defined using pure wavelengths for the primaries: R=630nm, G=532nm, and B=467nm.</p>
<p><a href="https://i.sstatic.net/GaIIs.png" rel="noreferrer"><img src="https://i.sstatic.net/GaIIs.png" alt="Various RGB gamuts plotted in CIE chromaticity coordinates" /></a></p>

CC BY-SA 4.0
2021-01-08T06:49:53.537Z
Right, but it might be better that you do not say "color mixtures"when you mean wavelength distributions. Because it makes the subject matter confusing as now colpr has many meaning.
joojaa
CC BY-SA 4.0
2021-01-08T08:42:30.643Z
Thank you, this is very helpful. together with the the answer of Kaan E., this pretty much answer my question.
Martynas Žiemys
CC BY-SA 4.0
2021-01-08T18:35:56.043Z
@joojaa I could say that they are a wavelength distribution or a spectral mixture, but I think this is also confusing as these primaries are not defined to be a _specific_ SPD. They are defined in terms of chromaticities which can be represented metamerically by an infinity of different SPDs.
Nathan Reed
CC BY-SA 4.0
2021-01-09T09:15:40.270Z
@Nathan yes i understand that. Our everyday language is not terribly good vhen we reach this level of abstraction. But still...
joojaa
CC BY-SA 4.0
2021-01-08T02:34:06.770Z
2021-01-08T02:34:06.770Z
Nathan Reed
<h1>The Context</h1>
<p>I am exploring the idea of making a DIY spectrometer(and colorimeter) for testing various material samples for interior visualization. It's sort of a hobby project for my curiosity and pleasure that might end up useful for my actual work with CG.</p>
<h1>The Question</h1>
<p>I am struggling to find a trustworthy information source for light wavelengths sRGB color space primaries are supposed to be. They are supposed to be the same as in REC.709 as far as I understand. <strong>Are the actual wavelengths of sRGB RGB primaries defined and if so what are they in nanometers?</strong></p>

CC BY-SA 4.0
2021-01-07T19:19:27.547Z
RGB are computed as weighted integrals over a whole range of wavelengths. I don't have the weight curves however. Never mind, I found this: https://en.wikipedia.org/wiki/CIE_1931_color_space#Color_matching_functions
lightxbulb
<color-science>
What wavelengths(dominant) the primary RGB colors are supposed to be in sRGB color space in nanometers?
Martynas Žiemys
# What wavelengths(dominant) the primary RGB colors are supposed to be in sRGB color space in nanometers?

(Asked by: username_0 on 2021-01-07)

# The Context

I am exploring the idea of making a DIY spectrometer(and colorimeter) for testing various material samples for interior visualization. It's sort of a hobby project for my curiosity and pleasure that might end up useful for my actual work with CG.

# The Question

I am struggling to find a trustworthy information source for light wavelengths sRGB color space primaries are supposed to be. They are supposed to be the same as in REC.709 as far as I understand. **Are the actual wavelengths of sRGB RGB primaries defined and if so what are they in nanometers?**

**Tags:** color-science

> **Comments:**
> **username_1**: RGB are computed as weighted integrals over a whole range of wavelengths. I don't have the weight curves however. Never mind, I found this: https://en.wikipedia.org/wiki/CIE_1931_color_space#Color_matching_functions  

---

## 2 answers

### Answer by username_2 on 2021-01-08. Score: 1 | Accepted answer

Trichromatic color system is based on using 3 carefully selected reference spectral power distributions(SPD) as you imagine. CIE uses its own reference SPDs, but there are others who prefer using other SPDs as reference. So the answer to the question

> Are the actual wavelengths of sRGB RGB primaries defined and if so what are they in nanometers?

differs, or might differ, with respect to institutions. As for trustworthy resources:

Scott Burns had kindly provided some reference SPDs in his [website](http://scottburns.us/fast-rgb-to-spectrum-conversion-for-reflectances/).

For illuminants and observers etc. you can check the [website](https://www.rit.edu/cos/colorscience/rc_useful_data.php) of Munsell Color Science Lab.

> **Comments:**
> **username_0**: Thank you. This is exactly what I was looking for. It will be interesting to compare the SPDs of primaries of real monitors with this if I ever manage to make the spectrometer.  

---

### Answer by username_3 on 2021-01-08. Score: 5

The primaries of sRGB are not pure wavelengths, they are color mixtures. Their true definition is in terms of CIE chromaticity coordinates. That said, for sRGB, the red primary is close-ish to 610nm, green is very roughly 555nm, and blue is close-ish to 465nm.

The Rec. 2020 RGB space, by the way, is actually defined using pure wavelengths for the primaries: R=630nm, G=532nm, and B=467nm.

[![Various RGB gamuts plotted in CIE chromaticity coordinates](https://i.sstatic.net/GaIIs.png)](https://i.sstatic.net/GaIIs.png)

> **Comments:**
> **username_4**: Right, but it might be better that you do not say "color mixtures"when you mean wavelength distributions. Because it makes the subject matter confusing as now colpr has many meaning.  
> **username_0**: Thank you, this is very helpful. together with the the answer of username_2., this pretty much answer my question.  
> **username_3**: @username_4 I could say that they are a wavelength distribution or a spectral mixture, but I think this is also confusing as these primaries are not defined to be a _specific_ SPD. They are defined in terms of chromaticities which can be represented metamerically by an infinity of different SPDs.  
> **username_4**: @username_3 yes i understand that. Our everyday language is not terribly good vhen we reach this level of abstraction. But still...  

---

