sRGB is often contrasted with "linear RGB."

* Images are stored on disk and passed to displays in **sRGB,** which is approximately perceptually uniform in intensity.
* Shader math is done in **linear RGB,** which is physically uniform in intensity.
* Gamma correction can be applied to convert between the two.

Now, sRGB has a standard that colorimetrically specifies its gamut, saying exactly where pure red, green, blue and white lie. But there is no corresponding standard for just "linear RGB." *Any* triangle on a chromaticity diagram could be said to be linear, and, indeed, there are several well known gamuts to choose from:

[![RGB gamuts](https://i.stack.imgur.com/gJHM8.png)](https://i.stack.imgur.com/gJHM8.png)

In practice, when we say "linear RGB," we mean "sRGB without the gamma correction." (This is implicitly what we're doing when we apply sRGB gamma correction as a final post-processing step but ignore color spaces for the rest of the rendering pipeline.)

But why is *that* RGB gamut the correct one to use for interpolation and lighting calculations? It seems arbitrary. If anything, wouldn't we want to use the largest possible gamut for internal calculations, and then clip or scale colors to the output device's gamut at the very end?

Is it that RGB lighting is going to be approximate no matter what, so it doesn't matter which gamut we pick, and we may as well pick the one closest to what the display natively supports? Is it just negligence? Or do calculations in these different gamuts actually yield the exact same results, somehow?