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

Am Mittwoch, 27. April 2016, 18:18:38 schrieb Elle Stone:
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]?


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

Good, thanks for checking.

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.

Yes, what would you suggest? Using a different encoding for the TRC?

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.

So is darktable's internal sRGB profile (the one you can select in "input color 
profile"). We just export with a V2 to make it easy to actually look at the 
image. And I don't expect people to export float images in sRGB.

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).




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