Re: [Gimp-developer] darktable linear Rec709 doesn't match GIMP linear sRGB

[Elle Stone <ellestone ninedegreesbelow com>]

On 04/27/2016 05:11 PM, Tobias Ellinghaus wrote:
> Am Mittwoch, 27. April 2016, 10:55:14 schrieb Elle Stone:
> > The darktable plug-in linear Rec 709 chromaticities don't match the GIMP
> > built-in sRGB chromaticities.
>
> Thanks for bringing that up, I changed the sRGB profile a while ago but somehow
> forgot the others. I pushed a change to create profiles that match your sample
> set. Could you please have a look at them [0]?
>
> [0] https://houz.org/tmp/darktable_profiles_2.0.4.tgz

Using iccToXml to check the colorants and chad, the colorants and chad 
are perfect for all four profiles.

The darktable sRGB profile is a "V2 according to V4" profile with a 
point TRC. So this profile clips out of gamut channel values in floating 
point images.

GIMP's internal sRGB profile is a V4 profile with a parametric TRC, so 
GIMP's sRGB profile doesn't clip out of gamut channel values in floating 
point images.

I don't know what the actual rationale is for darktable to make a V2 
version of sRGB. But at this point in time a V2 profile is the right 
choice for output to the web, for maximum compatibility with the various 
browsers (even Firefox doesn't read V4 profiles unless the user changes 
the gfx settings in about.config).

Best,
Elle