alt Hacker Newsperceptual distance is quite different from Euclidean distance in this RGB space. Like if put two swaths of color side by side and said “how similar are these?” to samples of people, the groupings would not much resemble this cube.
They’ve done this! It’s shown on a “chromaticity diagram”, and is useful for comparing what colors different screens/printers/etc can reproduce. (It’s 2D not 3D cause it’s normalized for luminance or brightness.) Color science is weirdly fascinating: