A few questions on monitor calibration

Hardware
1

Prologue:

  1. I’ve read Display Color Profiling on Linux and DisplayCAL—Display Calibration and Characterization powered by ArgyllCMS

  2. Hardware/Software:

  • 3 monitors connected via an nvidia 750Ti FTW
  • All monitors are 1080p-ish
  • Fedora 26
  • KDE/Plasma Desktop 5.x - whatever’s the latest in Fedora 26
  • RawTherapee
  • Digikam

Questions:

  1. How close does the calibration step (what DisplayCal says is the interactive) step - get me to more accurate monitors?

  2. DisplayCal’s website says it supports multiple monitor setups. Does anyone know if KDE supports loading more than one profile? If not, does it apply the profile to all monitors, or can I specify that it get applied to my photography monitor?

  3. Would I need to do anything to get RawTherapee to make use of the profile? Either in general or to make sure it’s using the profile of my photography monitor?

  4. Same question for Digikam.

2

To the best of my knowledge:

Depends on the monitors. I’m not aware of being able to load a LUT into the VCGT on a per-monitor basis. Unless that is possible, you should reset your VCGT (argyll-dispwin -c) and create profiles which rely on it being linear.

It’s not a question of KDE or of GNOME, but of the color management system underneath. colord might. It did not work correctly last time I tried it (some 3 years ago now). Neither did Oyranos.

The color management service does not apply a monitor profile to any monitors. What it does is it informs color-managed programs of which profile they should be using. If a program is not color-managed, KDE/GNOME/Oyranos/colord/Windows/etc won’t help.

All you need to do is to select the correct monitor profile in the combobox under the main preview matching the monitor the preview is on. As for that being done automatically for you, since all color management systems were broken in KDE last time I tried them, I don’t know whether RT will auto-detect the right profile if you have more than one, and I don’t know whether it will automatically switch profiles if you drag the RT window from one monitor to the next. @agriggio implemented the monitor profile auto-detection code, maybe he knows.

3

RT essentially relies on GTK for detecting the profile. It should do this correctly for the monitor you start the application in, but it will not switch if you move the window to another screen. However, you can still select the new profile manually from the combo box at the bottom – that always works :slight_smile:
I think it should be possible to switch automatically, I am just not that good with GTK so I didn’t do that.
Hope this helps