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Roughly, we have three types of color-sensitive cone cells in our eyes. They each have different behavior in terms of how much they "react" to different wavelengths of light. Take a look at this chart: https://en.wikipedia.org/wiki/Trichromacy#/media/File:Cones_... Each individual wavelength activates all three to some extent: think about this as a point in 3d space. For example, 400nm corresponds to something like (0.1, 0.05, 0.0), from that chart. 500nm might be (0.1, 0.4, 0.3). But we experience a mix of many different wavelengths at once. So we can not only experience just these points in 3d space, but we can also experience any linear combination of any of these points. For instance, a mix of half 400nm and half 500nm light might be "sensed" by us as (0.1, 0.225, 0.15), even though maybe there's no individual wavelength that corresponds to that point. Any linear mix of any number of any wavelengths covers the entire gamut of what we can perceive. The question then for someone picking primary colors for an additive display is: if I can only do a linear mix of three wavelengths, what wavelengths should I pick? What covers the biggest subset of the whole perceptible gamut? It just so happens that red, green, and blue do the best. If you swapped green for yellow, there would be a section in that 3d space that you could no longer create. Specifically, the area where M cones are strongly activated compared to L and S. Unsurprisingly, this would be the greenest greens. |
