Can we calibrate the monitor's HDR EOTF using a MHC2 tag embedded ICC profile?

[Globefishp]

I notice that not all monitors can follow PQ curve very well, partly because some monitors are lack of PQ curve and grey balance calibration.
In SDR content, we can use vcgt tag to calibrate grey balance and EOTF.
I wonder whether we can do the same thing in HDR mode? Are there any useful block in MHC2-compatible ICC file to do such calibration? If so, I would like to know how can I use the tool to achieve that, given DisplayCAL+dogegen can measure HDR patches and somehow store the tone response curve in a legacy SDR ICC.
Techinically, a legacy ICC file has the info of max and min luminance of the monitor, now combining with the tone response curve stored in the ICC, actually we can deduce the correction curve to a PQ target (either hard clip or some have some slope). I wonder if there's such tool to do that?

[dantmnf]

Yes, MHC2 LUT works in HDR mode, but the in-monitor gamut mapping may interfere with 1D-LUT calibration (especially RGB balance). With that said it should be still possible to calibrate grayscale EOTF by applying identical LUT to RGB channels.

I'm not aware of any free tool to do that. Using traditional SDR workflow on PQ EOTF could be affected by ABL and/or some random highlight mapping behavior.

[Globefishp]

So It's possible to do such calibration once you have the measured 3 channels EOTF. The RGB curve could be different to better calibrate grey balance right? Do you have any interest to add a feature in MHC2gen that:

1. Read ICC profile which contains RGB three channel tone curves measured in HDR mode.
2. Generate three 1D-LUT that map the measured tone curves to ideal PQ curves (to be simple, let values over the maximum of monitor be clipped)
3. Write to a MHC2-compatible ICC files which can be loaded by Windows in HDR mode

The only thing I'm not sure is whether Windows can accept three 1D-LUTs (R/G/B one per channel, like what vcgt does), or only one 1D-LUT for all three channels?

[Globefishp]

If MHC2gen can have such feature, We probably can do HDR calibration using free tools FINALLY, by combining DisplayCAL+dogegen+MHC2gen?

[Auxx]

@Globefishp according to MS docs on MHC2, it support 3 1D LUTs (R, G and B).

Now the question - can we generate these 3 LUTs with DisplayCAL somehow and pack them into MHC2 ICC profile? Does anyone know how to do that?

[ttys001]

If MHC2gen can have such feature, We probably can do HDR calibration using free tools FINALLY, by combining DisplayCAL+dogegen+MHC2gen?

Hi You may check out my repo on creating HDR profile: https://github.com/ttys001/MHC-ICC-Profile-Maker