- Some questions frequently asked by houseowners : are there only 4 unique hues in human colour vision?
♥ "when human observers are asked to adjust a coloured light such that it appears neither red nor green or such that is appears neither yellow nor blue, most colour-normal observers have no difficulty in making these adjustments and these colour appearance judgements are not influenced by culture and language or by age. this suggest that there is something very fundamental about these four attributes: redness, greenness, yellowness and blueness." (source: wuerger, s.m, atkinson, p. and cropper, s.j. (2005), the cone inputs to the unique-hue mechanisms) my question: isn't this true for "purple that is neither red nor blue"? are the four colours above more unique, more fundamental than purple for instance? some additional facts: red and green are not opponent colors! just look at a - good - color wheel. reds opponent is cyan. looking at the cited paper's diagram you can see the same. i also understand color mixing and color opponency. however i don't see why those four specific colors are considered as fundamentals. you cound easily pick two other opponent pairs from the color circle. in the human eye there are 3 types of cones, but they do not correspond to red, green and blue. they respectively have peaks at 420 nm, 534 nm, 564 nm, which correspond to: blue, bluish-green, yellowish-green. so the cones are not responsible for the unique hues.