Darktable not correctly displaying Display P3 color space?

[CommunyAS (Andre Spatzier)]

Getting a little deeper into darktable (3.8.0 - great work, dear developers ) I wanted to set it to export photos making use of retina display capabilities. The reason is that I watch my photos almost exclusively on Apple devices that all have a retina displays using the Display P3 color space.

I downloaded Display P3 ICC profiles from https://github.com/saucecontrol/Compact-ICC-Profiles and copied them to my home directory folder ($HOME/.config/darktable/color/out). Export works good with DisplayP3-v4.icc and DisplayP3Compat-v4.icc.

Comparing exports using sRGB and Display P3 profiles (as well as AdobeRGB) with what I see in darktable - lighttable and darkroom - (i.e. is displayed on my MacBook Pro 2021) I realised that darktable obviously does not show the colors correctly in Display P3 color space like it should on a MacBook Pro 2021 (although display profile in darktable is set to system display profile).
To be more precise: The darktable screen does not show a larger color space clearly visible on Display P3 exports, but rather matches with the “reduced colors” on sRGB exports.

… it is just impossible to edit photos making use of larger color spaces (like Display P3) if one cannot see the result on the screen…

As far as I know, Apple’s color profile “is based on the DCI-P3 D65 color space but uses the sRGB transfer function” (see https://github.com/saucecontrol/Compact-ICC-Profiles).

Could it be that darktable does not read the MacBooks color profile specs correctly?
Or has darktable is a problem with Apple’s color profile sRGB transfer function?

[betazoid (Anna)]

Have you profiled your screen with a colorimeter and created the profile with a software such as Displaycal?

[Matt_Maguire]

@CommunyAS

Could it be that darktable does not read the MacBooks color profile specs correctly?
Or has darktable is a problem with Apple’s color profile sRGB transfer function?

This is a well-known problem with the GTK+ implementation on Mac OSX, and has been discussed multiple times in this forum, for example:

Wide-gamut preview in macOS

@Morgan_Hardwood @houz @paperdigits @patdavid WARNING: long message ahead… Yesterday evening I have finally managed to bypass the OSX UI color management and to send pixel values directly to screen… below I will try to describe how I got there. Foreword 1: I am shocked by the Apple API documentation… I have looked into many Open Source libraries, made by volunteers during their limited spare time, and each single one I have checked had an API documentation that was 100 times better than Apple…

It’s one of the reasons I switched to using Linux for most of my photo editing.

[CommunyAS (Andre Spatzier)]

Thanks for your quick replies.

@betazoid

Have you profiled your screen with a colorimeter and created the profile with a software such as Displaycal?

It might be good to profile the screen (which I have not done), but I don’t think its necessary firsthand since being able to see a wide gamut result is sufficient for me (at least for now).

@Matt_Maguire

This is a well-known problem with the GTK+ implementation on Mac OSX, and has been discussed multiple times in this forum, for example:

I didn’t know about that, thanks for this hint. However, at least the solution you linked (I will check it out) was posted five years back. So perhaps meanwhile the problems could be solved from within darktable.

[Matt_Maguire]

@CommunyAS

perhaps meanwhile the problems could be solved from within darktable.

not possible, it needs to be dealt with at the gtk layer.

[CommunyAS (Andre Spatzier)]

I hope that there will be a solution soon.

Unfortunately, I don’t fully understand how to apply the workflow you posted, since I have no experience in app development. I only can guess that he probably made it work from within PhotoFlow…

I just noticed that switching of True Tone in the MacBooks Display settings darktable gets a little closer to showing the colors visible on the Display P3 exports.

Any more suggestions to fix this problem are very welcome…