Originally posted by Anvh yes and no, the reason for this is what kind of red, what kind of blue and what kind of green do you mean, there are so many shades.
RAW uses his own unique rgb values and is as such not restricted to one particular defined pallet, such as sRGB, aRGB, prophotoRGB or CMYK, who says a sensor need to use only red green and blue?
Whit Astro photography often special filters are used to show different elements in the photo for example, I know it's not standard photography but it shows you can use more.
What I'm suggesting is that it's problematic to say that a camera sensor has no color space. It's definitely RGB, and no question about it. I think there's some confusion here due to terminology. sRGB, Adobe RGB, etc. are subsets of RGB. They're limited to a portion of the entire RGB color space. The gamut of RGB is defined as "every visible color," and all visible light is composed of red, green, and blue primaries. There are other colors at either end of the spectrum - ultraviolet on one end, infrared on the other - but these aren't part of the visible spectrum. The red sensors on a camera sensor might pick up some infrared, and the blue might pick up some ultraviolet. But there are very definite primaries in red, green, and blue. There does not exist a visible color that cannot be constructed from pure red, green, and blue. That said, any sensor's effective primaries vary from the absolute wavelengths of red, green, and blue, but they are still red, green, and blue primaries. As far as I know, there does not exist a sensor that can take in the entire spectrum of RGB - even a camera sensor is limited to some subset of RGB. So there is an RGB color space for every camera's RAW. And sensitivity varies among human eyes. Some people see more colors and gradations of colors than others. Even the human eye sees a subset of RGB.
CMYK is a different beast altogether. It is a subtractive color model that can only be simulated on-screen because (essentially) all screens use RGB, and RGB is an additive color space. True, there are televisions and monitors that use an additional "primary." But the additional primary (usually yellow) isn't a true primary; it's a mixture that makes up for the limitations of the screen's necessarily imperfect red, green, and blue primaries.
LAB and HSB are descriptive tools, not true color spaces.