Force Windows to reload color calibrations

Control Panel -> Color Management -> Advanced Tab has a button "Reload current calibrations", which apparently makes Windows to re-upload the video card's/driver's LUT table with the data from the currently specified monitor profile.

I would like to have a direct shortcut (say, literally: a desktop shortcut) that performs the same action. Is there a way to do that?

I see that Windows loads/reloads color calibrations based on a task stored in Task Scheduler under Microsoft -> Windows -> Windows Color System as "Calibration Loader". So, alternatively the above question can be rephrased as: how can I create a shortcut that would forcefully run a specific task from Task Scheduler? A naive attempt to drag-and-drop a task from Task Scheduler to the desktop does not work.

Inspection of the aforementioned task details reveals that internally it invokes C:\Windows\System32\mscms.dll in some way. So, perhaps someone knows which entry point from that DLL I can "rundll32" to make Windows reload the calibrations?

P.S. Yes, there are third-party utilities that do exactly that, but since this functionality is already part of Windows itself, I'd prefer to use what's already there.

You could write a script but using a 3rd party might in this case be a lot easier. hth.

krism said:

You could write a script but using a 3rd party might in this case be a lot easier. hth.

Click to expand...

Well, turns out one solution is indeed to manually trigger the Task Scheduler task, which can be done as

schtasks.exe /run /tn "\Microsoft\Windows\WindowsColorSystem\Calibration Loader"

(Appears to require Administrator privileges). This can be wrapped into a desktop shortcut.

AndreyT said:

Control Panel -> Color Management -> Advanced Tab has a button "Reload current calibrations", which apparently makes Windows to re-upload the video card's/driver's LUT table with the data from the currently specified monitor profile.

Click to expand...

Is there documentation of what exactly this stuff does and how it works?

I've used Calman and an i1D3 meter for over 10 years, and I rely on their Client 3 software to manage monitor profiles. Spectracal (now Portrait Displays) told me that Calman adds a 1D LUT to the ICM profile it creates for Windows, but Windows color management ignores it. In fact, going to Display Settings causes Windows to load the profile and undoes the LUT, which is instantly and visibly noticeable. I have to go to Client 3 and reselect it, which loads the LUT back into the video card. They said there was no way to detect when Windows zeroed out the LUT.

This 1D LUT is important, because it provides all the benefit for applications that aren't color managed. I've always thought Windows color management was only for color-managed apps.

barreleye said:

This 1D LUT is important, because it provides all the benefit for applications that aren't color managed. I've always thought Windows color management was only for color-managed apps.

Click to expand...

Yes, loading the LUT makes color rendition much better for all applications (not as good as it can be, since the rest of the profiling info is stored in non-LUT-able part of ICM profile and used only by color-managed apps), but still better.

Back in XP/7 era Windows could only associate the ICM profile with the monitor. Windows did not go further than that. The intent was that ICM-aware apps could retrieve that profile and use it in any way they see fit. However, even in that era it was possible (or even necessary) to pre-load LUT info from the ICM profile into the video card's LUT table using third-party startup utilities, like Adobe Gamma Loader, X-Rite Loader and such. Apparently, most color-managed applications assume that LUT has been properly pre-loaded. So, they just use the rest of the ICM profile accordingly.

Starting from Windows 10 the ability to pre-load the LUT became part of Windows, i.e. the "Adobe Gamma Loader"-like functionality is now integrated into Windows itself, so there's no need for a separate utility. To activate LUT pre-loading in Windows one just needs to select "Use Windows display calibration" in "Color Management". Other than that, nothing has changed.

barreleye said:

I've used Calman and an i1D3 meter for over 10 years, and I rely on their Client 3 software to manage monitor profiles. Spectracal (now Portrait Displays) told me that Calman adds a 1D LUT to the ICM profile it creates for Windows, but Windows color management ignores it. In fact, going to Display Settings causes Windows to load the profile and undoes the LUT, which is instantly and visibly noticeable.

Click to expand...

"Windows color management ignores it" is apparently something that applies to Windows XP/7. Starting from Windows 10 it no longer ignores it, if you ask it not to (see above).

Yes, loading the LUT is instantly and visibly noticeable. However, I see exactly the same changes in screen color rendition when I load the LUT using X-Rite LUT loader and using built-in Windows functionality ("Reload current calibrations"), which is what made me believe they are doing the same thing.

AndreyT said:

Starting from Windows 10 the ability to pre-load the LUT became part of Windows, i.e. the "Adobe Gamma Loader"-like functionality is now integrated into Windows itself, so there's no need for a separate utility. To activate LUT pre-loading in Windows one just needs to select "Use Windows display calibration" in "Color Management". Other than that, nothing has changed.

"Windows color management ignores it" is apparently something that applies to Windows XP/7. Starting from Windows 10 it no longer ignores it, if you ask it not to (see above).

Yes, loading the LUT is instantly and visibly noticeable. However, I see exactly the same changes in screen color rendition when I load the LUT using X-Rite LUT loader and using built-in Windows functionality ("Reload current calibrations"), which is what made me believe they are doing the same thing.

Click to expand...

I don't understand how to reconcile the "Use Windows display calibration" option with the profiles that I made in Calman. When I enable the former, it throws out the Calman LUT. The only way to get the Calman LUT back is to use Client 3; selecting the profiles in Windows Color Management doesn't load it.