new NVIDIA graphics card pictures previously edited in darktable look wierd


I upgraded my NVIDIA graphics card in Ubuntu (plasma desktop) and I am presently waiting for DisplayCal to finish calibrating my old Widegamut monitor and create a new profile.

In the meantime, I re-opened Darktable and all my photos that I had edited and were ready for export now look too dark, high contrast, and saturated. I tried various input profiles but will stick with the standard matrix hoping that the updated ICC profile will make a difference in how the pictures look.

Can anyone confirm if there is any other adjustments that need to be made in Darktable? Do I have to start all over with my edits even though I was using the modern filmic pipline?

I checked what is being used for my input color profile module; standard color matrix, and I think I saw my previous display ICC profile? Shouldn’t it be my camera profile (Nikon D5500)? If that is the case, can I switch it back to default or will it furthur mess up my edits?

Wait for your monitor calibration to finish. Make sure darktable is using the new profile.

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There are multiple profiles at play.

  • The first module involving profiles is input color profile. See darktable 4.0 user manual - input color profile.
    • The input profile tells darktable how to interpret the values recorded by the camera. Usually, you are safe to use the default standard color matrix profile. Using a display profile here makes absolutely no sense.
    • The working profile defines what darktable uses for internal processing. Unless you really have some special process, leave it at its default of linear Rec2020.
  • The display profile tells darktable how to display your image. Use your display profile here. See darktable 4.0 user manual - display profile.
  • The output profile is for your output file. See darktable 4.0 user manual - output color profile.
  • There’s also the soft-proof profile and the histogram profile; the former is only used if you enable soft-proofing; the latter should not alter how your image is displayed. See darktable 4.0 user manual - soft proof.

Locations of profile files (Linux paths):

  • put input (camera, scanner) profiles under $HOME/.config/darktable/color/in
  • put output profiles under $HOME/.config/darktable/color/out. This is also used for soft-proof profiles (since you are soft-proofing using an output device).

Yes at first I was mixing up the display profile with the input profile when trying to understand things which are entirely different! I don’t even try to understand how the working profile is greater than what the display can view…I haven’t changed either of those profiles from the default though.

It seems like Darktable is now reading the updated display profile yet strange thing happens; although things still look weird either thumbnail or in darkroom view, when I export to either Tiff Rec709 or sRGB and import in Gimp or Krita, which are colour managed, the result is pretty much as I wanted it to be. (Good enough to use as image sequences in Cinelerra or Natron).

Update; I just ran the darktable-cmstest and it turns out that my main monitor atom & colord profile do not match! It seems to be a bug in KDE and a few other desktops where the primary monitor is not seen as the first display (my widegamut display is DP while the other screen is via HDMI port). I am confused on how to fix it & it was supposed to be corrected just not sure if for Ubuntu 20…

I use a shell script to launch darktable. In that script, I include a command to load the display profile:

dispwin -I "/oldhome/shared_data/media/digicam/colour-management-profiles/dispcalGUI/storage/HP ZR22w #1 2022-08-20 18-52 0.3127x 0.329y sRGB S 1xCurve+MTX/HP ZR22w #1 2022-08-20 18-52 0.3127x 0.329y sRGB S 1xCurve+MTX.icc"

On Ubuntu, dispwin is part of the package argyll.
I think the following options allow you to work with multiple displays (I just have one):

-display displayname Choose X11 display name
-d n[,m]             Choose the display n from the following list (default 1)
                     Optionally choose different display m for Video LUT access
   1 = 'Monitor 1, Output DP-2 at 0, 0, width 1920, height 1080'

I did a fresh install Ubuntu Studio 22.04 on a spare partition. It is using the lastest KDE plasma desktop, so I am hoping that they have setup a better way for x atom & colord to work together. I will see if Darktable & all other graphic programs will be color managed by my custom profile. (Supposedly Gnome desktop was setup to work more smoothly).

As far as this installation, can such a script be installed in the settings: add custom script section as well?
Note: My second screen does not use the same custom ICC profile since its a generic HDMI monitor while my main monitor is an older widegamut W-CCFL.

In passing, another option I would like to do is to work from one installation to another, but I am confused what needs to be loaded exactly for it to work, the directory & the point to the file?

I’m sorry, I don’t know what that is. Lua? I don’t use Lua.

I re-verified and Its actually a section to add custom css scripts, so not the same thing at all.
After much trouble trying to add the appropriate terminal input for colord default profile, I have the desired profile system-wide in Ubuntu Studio 22! I also discovered that I can set darktable to either colord or system wide profile, by pressing the small display icon on the bottom right, which is very useful. I’m still a bit unclear; If I ever need to add a customization to darktable as you have done, what is the exact code needed so that it is launched in Darktable? Is there a section in the manual that clarifies this?

That is for the UI elements (colour of labels, background and the like).

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