Re: [Gimp-developer] Some blend modes break in unbounded mode sRGB

[Gez <listas ohweb com ar>]

El vie, 11-04-2014 a las 02:39 +0200, Przemyslaw Golab escribió:
> Isn't that expected? You don't change color space, for it to have the same
> results.
>
> You choose best color space for the job and use it from beginning to the
> end,
> or if you know what you are doing convert it in middle of work to do the
> thing
> you want to do.
> If all color spaces look the same whats the point of using them.

Hi Przemyslaw,

Unless I got it absolutely wrong, the plan for GIMP 2.10 is to use
forced unbounded colorspace conversions to sRGB for the internal
pipeline (at least that's what I got from Drawoc's reply to Elle's
previous post).
So anytime you open a wide gamut image, it will be converted internally
to sRGB for all the processing and compositing.
Since the unbounded conversion is reversible (unlike the usual icc
bounded transforms that are destructive), in theory you could go back to
your wide-gamut colorspace with no loss of color latitude upon export
(once you're done with processing).
What Elle is describing here is a number of operations that don't seem
to work with unbounded sRGB (where values can go negative or >1 to
express out of gamut colors and keep the excess gamut from the source
wide gamut profile).

I've repeated Elle's tests and tried my own tests, and I can see that
some operations do break.
I'm really interested about this issue, because some basic and important
math operations seem to have issues with those out-of-bounds values
(like multiplication/division).

Gez.