Derek Wells wrote:
The saturated-blue-into-purple "problem" is due to the perception of constant hue being nonlinear with increasing chroma, rather than being modelable as a straight line (or, at least, a relatively "simple" curve), with this nonlinearity being most marked in the blue part of the spectrum.
Yes, the basic problem is that perceived hue doesn't have a simple relationship to any underlying measurable quantity. If you take light with a single dominant wavelength and change the saturation (== purity), then the apparent hue changes (Abney Effect). If you change the luminance the apparent hue changes (Bezold-Brücke Hue Shift). Mark Fairchilds book "Color Appearance Models" covers all this: <http://search.barnesandnoble.com/Color-Appearance-Models/Mark-D-Fairchild/e/9780470012161/?itm=1&USRI=color+appearance+models> Graeme Gill.
