Elle Stone (l.elle.stone@xxxxxxxxx) wrote: > On 10/9/13, Simon Budig <simon@xxxxxxxx> wrote: > > Another (slightly philosophical) issue for me is, that you never explain > > what you mean by color. > > I added a one-paragraph summary of color: > http://ninedegreesbelow.com/photography/xyz-rgb.html > What do you think? Will my one-paragraph summary work? Yeah, I like it. > > I am not sure if mentioning this helps or if it confuses stuff... :) > Based on your input I rewrote the explanation of imaginary colors, > hopefully clarified what a "real" color really is, and touched on the > subject of nonstandard color perception. Metamerism, though very > important, might be more distracting than helpful? Yeah, Metamerism probably is distracting. For my mental model of color the spectral distribution of the light is quite important and I wonder if it would help a color-newbie to have more of this "tangible" stuff in the text. But this certainly also is a question of personal preference and I don't want to impress my views onto your text :) To look at the weaknesses/hypothetical problems of the XYZ model there are two things worth noting: a) two distinct spectral distributions might end up at the same XYZ coordinates. b) there are XYZ coordinates in the first octant, which can not be mapped back to a spectral distribution. (put in mathematical terms: XYZ is neither injective nor surjective) And I'd explain it by looking at the monochromatic light (visible to the "average human"), which has a very specific position at the border of the horseshoe. By adding up more wavelengths you'll always end up inside the horseshoe, (and there is more than one way to add up monochromatic light to end up at a certain XYZ coordinate). On the other hand, creating an actual light source with XYZ coordinates *outside* the horseshoe is an impossibility, even for rocket scientists, unless we assign XYZ coordinates for invisible wavelengths or allow for "negative" light sources... The human aspect of XYZ is visible in two aspects: first the limited spectrum we consider and then the weird shape of the horseshoe, which is determined by the response curves of the "average" cones in the human eye. But only the first one has an effect on the "reality" vs. "imaginarity" of a XYZ coordinate IMHO. However, adding tons of more diagrams with spectral distributions, X/Y/Z response curves etc. would at some point destroy your intentions with your text, so I won't complain... :) Bye, Simon -- simon@xxxxxxxx http://simon.budig.de/ _______________________________________________ gimp-developer-list mailing list List address: gimp-developer-list@xxxxxxxxx List membership: https://mail.gnome.org/mailman/listinfo/gimp-developer-list
