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My apologies if this is a dumb question or has been asked before. I looked at the FAQ and I also searched relevant keywords in the search tool but didn’t see a topic asking this upon quickly browsing through the results.
So, I’ve got my display profile set through DisplayCal, or rather, through Windows Color Management (the only option I see in displaycal is to let the OS handle color management). When I switch the profile or reset the VCGT and then re-assign my profile, I do see subtle changes in color rendering across the desktop etc. Which makes me wonder, is it really necessary to select my display profile within programs like GIMP, Darktable, or RawTherapee in addition to this? Does this not cause a double-correction?
When a program supports color management with ICC profiles usually it has an option in its configuration (a check box) to request to OS which is the default profile, so enabling it and restarting app there is nothing more to configure.
Also OS only publishes profiles, app must ask for it and have a color management engine to be able to appy it, or request OS CM module to do it for that app for at leats for windows there is no doble applied profile.Some programs do not suport properly color management 100%, an is example GIMP (2.10.28), only canvas is color managed, color picker is hit & miss (match canvas at toolbox, rendered sRGB in picker)… so it may be confusing. However it has improved, prevous versiosn where even worse, the was an old fork called “color corrected edition” taht solved most of these problems.
I mean, enable check box to use default display profile publiseh by OS to apps, then carefully check if these GNU apps are actually using it properly in your setup. I had bad experience with older DarkTable/RawTherapee but they may have improved using them with a widegamut monitor.Yeah, I have those boxes checked, but let me rephrase the question.
So, if I use the displaycal option to reset the video card gamut table the calibration is undone system wide. I can tell due to subtle changes in the color rendering on the desktop and start menu icons etc. Then if I re-apply the calibration, the calibrated profile is restored. This indicates to me that the calibration is loaded into my video card so that all output has the color corrections applied. If that is the case, then isn’t having various programs set to use the calibrated profile actually applying the correction twice to whatever photo is showin in gimp/darktable/etc?
Yeah, I have those boxes checked, but let me rephrase the question.
So, if I use the displaycal option to reset the video card gamut table the calibration is undone system wide. I can tell due to subtle changes in the color rendering on the desktop and start menu icons etc. Then if I re-apply the calibration, the calibrated profile is restored. This indicates to me that the calibration is loaded into my video card so that all output has the color corrections applied.
The only correction applied (windows) is grey, VCGT calibration loaded in to GPU
If that is the case, then isn’t having various programs set to use the calibrated profile actually applying the correction twice to whatever photo is showin in gimp/darktable/etc?
They do not know or care about VCGT, they care about TRC (tone response curve) stored in ICC file, call it after calibration “gamma”. Hence VCGT calibration for grey must be applied on GPU (DisplayCAL tray loader) in order to the TRC (measured after calibration, in profiling stage) in profile be a match for monitor with grey calibrated.
Otherwise display ICC profile will say “display has a fairly neutral grey gamma 2.2”, but display without grey calibration may have gamam 2.0 an severe pink or geen tin across grayscale.
Monitor + OSD tweaks or presets + VCGT in display ICC = behavior described by display ICC
(in an ideal monitor that needs no grey calibration VCGT wil be linear so it won’t matter if it is loaded or not)
