Differential geometry and color perception
SummaryCombined with well known facts about the affine structure of color space P, a local homogeneity hypothesis implies that P=G/K is equivalent to either R+xR+xR+ or R+SL(2, R)/SO(2). The G-invariant metrics yield in the first case Stiles' generalization of Helmholtz' color metric, in the second a new color metric with respect to which P is not isometric to a Euclidean space. The paper contains an extensive historical introduction.