What color system best differentiates Yellow/Red/Black?

Question

I'm working on a image processing system to segment three different types of pixels that are more or less Yellow/Red/Black.

Now my question - which I though it's best to be asked here - is that which Color system can best best differentiate these three colors in numeric values?

For example if we use RGB, Yellow and Red pixels, will have very similar values in their Red channel (close to 255) which makes it not a good choice for this purpose.

Hope my question is clear.

Thanks.

Answer

Probably HSV or similar. The color will be denoted by the H component and the intensity (to differentiate saturated red and yellow from black) by the V component.

However, black is not a color, but rather the absence of lighting/intensity/etc., so I don't think there is a system that will absolutely separate the black from the other two. What you are looking for is a 3-space with spanned by a base formed by R, Y and K vectors. However, I think that K is always related to the other two (they are colors, K is not).

BTW: I think this question is at best marginally related to photography.

Check more discussion of this question.