Cybernetic Vermin posted:

sure, i just find the purple case to be especially weird somehow. like, had our eyes evolved to only have two kinds of cones we'd only "see" actual spectral colors (as dogs do), determining the perceived frequency by the intensity ratio, having mixed light always being seen as the average of its wavelengths. but then we got a third cone for sensitivity, and we got the weirdo case where the red and blue cones are excited without the green, which no longer corresponds to a frequency so we just invent a new color for it. and that when we talk about birds with five kinds of cones seeing more color than us they really "see" a frequency decomposition of the light.

well, old hat for most people i presume, i had just never thought about it properly.