There are no blues or reds at all if nobody is watching. Color is a purely perceptual phenomenon relying on properties of the eye and brain.
And if you are looking at a picture on a computer, the computer will call red a pixel with an rgb value of (255, 0, 0) even if nobody is looking at it.
That's also why RGB monitors display more than three distinct colors. The colors are synthesized in the brain. If we were orbiting a brown dwarf, we might talk about colors within the infrared part of the spectrum as if they were intrinsic properties of light.