In that case, what is the frequency of the light needed to create "salmon"? Or in other words: is "salmon", "fuschia" and other colors located on the frequency

In that case, what is the frequency of the light needed to create "salmon"? Or in other words: is "salmon", "fuschia" and other colors located on the frequency spectrum? If so - why do we have zillions of color spaces instead of just a simple frequency? (or wavelength) At the moment when you introduce color spaces, you start accounting for how our eye receptors are sensitive to frequencies and leave the realms of physics (mostly because the receptors differ from person to person) When you take a 450 THz wave, you say it it is "unambiguously red" because it is what happens to be the word for the signal which is triggered by that wave. In most of the people. Roughly the same way. What I am trying to say here is that a color is a concept as well defined as "pain". You can have all sorts of measures, but none is strict. Finally, there are no "red photons", or green or blue (you mention them) - this simply does not exist at all as a concept.