Re: [Gimp-developer] Attempt to summarize the discussion of my examples of what doesn't work in unbounded sRGB

[Teo Mazars <mazarst ensimag grenoble-inp fr>]

> > Hmm, I understand, then the default black-to-white gradient would
> > be non perceptually linear, which is more surprising than the
> > color-to-color gradient. I think I am now convinced this is
> > correct, but it will probably be puzzling to use.
> >
> > BTW, "gradient" is not such a good example because it's not related
> > to chromaticities, "Invert" would be a better one.
>
> I don't understand what you are trying to say. How is drawing a
> gradient
> from most saturated red to most saturated green in any given color
> space
> not related to chromaticities?

Well, a gradient operation doesn't have to know what are the coordinates of chromaticities. The two colors 
used for a particular gradient are given by the user, if he want the "from most saturated red to most 
saturated green", he just have to send the coordinates of the red and the green to the operation, which could 
be the scaled/translated [1.0, 0.0, 0.0], [0.0, 1.0, 0.0] for a GIMP user. Since we just say that the 
operation have to work in a linear color space, there is no issue with out-of-gamut values.

Is that correct? If so, that's why "Gradient" is not a good example. "Invert" needs to know what are the 
chromaticities because it uses them to compute the "inverted" colors.