Re: [Gimp-developer] The darktable plug-in isn't using the user-specified output ICC profile

[Elle Stone <ellestone ninedegreesbelow com>]

On 04/27/2016 05:43 PM, Tobias Ellinghaus wrote:
> Am Mittwoch, 27. April 2016, 12:00:32 schrieb Elle Stone:
> > > On 04/24/2016 12:30 PM, Tobias Ellinghaus wrote:
> > https://mail.gnome.org/archives/gimp-developer-list/2016-April/msg00098.html:
> > > > It's hardcoded to export 32bit float EXR
> > > > as linear Rec709 after opening up your regular darktable. Did you
> > > > manually
> > > > select the Canon or Nikon format in the open dialog?
> >
> > It would be nice if the darktable plug-in were modified to allow users
> > to choose their preferred output space.
>
> Yes.
>
> > But currently darktable does seem to force output to be in the darktable
> > version of linear gamma Rec709 (which isn't equivalent to GIMP's
> > internal linear gamma sRGB color space -
> > https://mail.gnome.org/archives/gimp-developer-list/2016-April/msg00116.html
> > -, but hopefully this can be changed).
>
> Should be fixed, see the other thread. Once you confirmed that the profiles are
> fine now we will release darktable 2.0.4.

Yes, the profiles are fine.

> > Right now GIMP is an "sRGB only" image editor. But this situation surely
> > won't last forever. Having a raw processing plug-in that only allows to
> > export in one color space (especially a color space that doesn't match
> > the GIMP built-in sRGB color space) seems to be a step in the wrong
> > direction.
>
> The reason I chose linear sRGB is that
>
> 1) we are exporting to EXR as the intermediate file, so we need a linear profile
> 2) GIMP seems to work best with sRGB images so far, so I used the linear
> version of that.
>
> I agree that it would be nice to have some choice there. Would default export
> to linear Rec2020 be better? Still hard coded, but a wider gamut. It seems
> GIMP asks about converting the colors anyway, so for people that want to work
> in sRGB that's just one click away.

At this point in time and given the hard-coded sRGB parameters in the 
babl/GEGL/GIMP code base, if the darktable plug-in can't be easily 
modified to provide users with a choice of export profiles, then 
converting the image to linear gamma sRGB seems to me to be the right 
choice (even though I'd love to suggest using linear Rec2020).

If a user wants to then convert the image to another RGB working space, 
that conversion can be done in GIMP, as you say "just a couple of clicks 
away". This assumes the exported darktable OpenEXR file doesn't clip out 
of gamut channel values, which I'm pretty sure it doesn't - at least the 
"out of sRGB gamut" channel values in my sample CR2 file were not clipped.

Best,
Elle