Are there real HDD ICC display profiles

[Lambert]

Some newer Dell monitors (e.g. U2723QE) have factory profiles „HDR ICC” with a profile tag MHC2, that is a tag of a „Windows HDR profile”.

As far as I know, according to ICC specification, an ICC HDR profile has to contain a CICP tag. At least, there is an ICC suggestion of using such a tag.

The ICC specification does not mention the MHC or MHC2 tag at all.

My question:

Is a profile with MHC2 tag a real and valid ICC HDR profile comply with ICC specification or is it an arbitrary action of Microsoft? Or is it a reliable solution?

[Vincent]

Try to redirect these question to ArgyllCMS maillist

[Ben]

I want MHC2 support to.   I think out of spec edid is messing up my windows 11 24h2 with Vizio V5-555-J01 using auto color managed.    I am stuck in SDR but my display does max out at 175 nits.    It was 200 something new but changed over time.   Still color accurate as it was though.   Trick is to calibrate it though.   Not a very pleasant gamma curve uncalibrated with ups and downs .

[Lambert]

I asked Mr. Gill about this topic. Here is his full answer:

“Sorry, I haven’t delved into HDR profiles or profiling to any degree at this stage,
simply because I don’t have any HDR displays or Windows 11 or Mac test machine to
investigate with, due to financial and time constraints. I hope there will an opportunity
to catch up on the HDR world at some stage in the future, but I’m not sure when that will be.

Having extra proprietary tags doesn’t invalidate a profile, it would only do so
if the profile was not useful without such tags.

As far as I interpret it, the Cicp tag is only useful when the profile represents
a standardized Video colorspace, where it can indicate a specific standard. So not
much use for a random display, unless the display itself has been calibrated to emulate
a standard Video colorspace.”

The question is still open:

Can we trust in HDR ICC profiling with Windows 11 tools or not?

[DaniJ]

What is your use case? Viewing or editing videos? Editing HDR images? Having Windows convert colorspaces? Having other apps convert color spaces while sending HDR video? Tonemapping?

[Lambert]

Complete display calibration/profiling for HDR moving picture and for a HDR monitor without own LUT. And for some usual video viewing and editing software.

Is it possible at all?  Or is this claim too broad?

[DaniJ]

https://learn.microsoft.com/en-us/windows/win32/wcs/display-calibration-mhc has lots of details.

When time permits, I’ll try to create such a profile and test it.

[DaniJ]

When setting my display in HDR mode, black (except 0) if lifted a lot. Should the MHC2 profile work, the improvements will be considerable.

[Lambert]

OK, thanks. But can be checked the overall accuracy of that profile? Or does exist a validation method for such profiles (ICC HDD)?

[DaniJ]

I’ve created a profile to demonstrate how a MHC2 tag works inside the Windows pipeline (whole desktop):

• Uses a MHC2 LUT to darken the image a bit – similar to VCGT tags but with higher resolution. This would be used to adjust whitebalance and EOTF.
• Uses a MHC2 matrix to invert red and blue. This would be used to adjust hues/saturations.

Because the colorant tags are also inverted, it makes it very easy to spot color managed apps because they will use the colorants to invert red/blue so they show up correctly thanks to double inversion. Non-color managed apps will be inverted by the Windows pipeline only once.

Feel free to try it out to see how it interacts with the apps you’re using.

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[DaniJ]

When I’ll create one from actual measurement data I expect it’ll be even better than classic SDR profiles thanks to the additional matrix compared to only VCGT.

[Author]

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