>> the ratio of perceptually distinct steps around a hue circle to those directly across through gray is greater than would be expected as a circle in an ordina

>> the ratio of perceptually distinct steps around a hue circle to those directly across through gray is greater than would be expected as a circle in an ordinary Euclidean space This is known as "the super-importance of hue", FWIW. > What if [...] we used geodesic curves in the original non-Euclidean metric? I came across a couple of examples of non-Euclidian colour spaces recently. 'Hyperbolic geometry for colour metrics': https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-22-10-12369&id=286233 https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-22-10-1... 'H2SI - A new perceptual colour space' (uses a four dimensional normalized Hilbert space, whatever that is): https://www.researchgate.net/publication/259265578_H2SI_-_A_new_perceptual_colour_space https://www.researchgate.net/publication/259265578_H2SI_-_A_...