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[Manni]

When I specify a SDR 3D LUT with OS HDR disabled, it's enabled when playing SDR content and disabled when playing HDR, as expected.

If I have OS HDR enabled, is there a way to use a HDR LUT (BT2020 PQ) for all content, as SDR Rec-709 can be tonemapped to HDR BT2020?

Does it make a difference if we disable HDR to HDR tonemapping?

I could do with a bit more accuracy, and if I could have a single HDR calibration for all content, I could use the native gamut with a large 3D LUT, which should produce decent results.

Has anyone tried this and has some results to share?

Alternatively, I heard that it was possible to use dwm_LUT (https://github.com/lauralex/dwm_lut) to generate a windows LUT, has anyone tried this with JRVR?

Any ideas, experiences and step by step welcome!

[Manni]

I found this old thread of mine that raised the question: https://yabb.jriver.com/interact/index.php?topic=138937.msg963262#msg963262

So the question to Hendrik is would there be a way to enable a separate 3D LUT for HDR Content, or would it be disabled when using HDR passthrough?

When using HDR to HDR tonemapping, JRVR is tonemapping before passing the content forward to the display, so hopefully it should be able to apply a HDR 3D LUT as the display shouldn't be doing any tonemapping?

When enabling OS HDR and using HDR to HDR tonemapping, SDR 709 would be tonemapped to HDR, so there is only the need for a single HDR LUT, that wouldn't be disabled when tonemapping to HDR.

Would this be possible? It would really help to increase picture accuracy in both SDR and HDR if we could use a single HDR LUT and the native gamut of the display to tonemap/correct all content.

[Manni]

I'm making progress with this little project

dwm_lut doesn't seem to be working with Windows 11 24H2, but I did some testing with Reshade (https://reshade.me/) using DirectX 11 and I was able to apply a 65^3 .cube 3D LUT while using HDR to HDR tonemapping with JRVR using the following shader:
https://github.com/aron7awol/CubeLUT3Ddith
This shows that it can be done

Unfortunately, I'm getting dropped frames, freezes and even crashes when Reshade is enabled, so a native implementation in JRiver would be much better. [EDIT: I've resolved the frame drops and crashes with Reshader, but a native support of a HDR 3D LUT by JRVR in one of the formats already supported would still be great.]

Hendrik, is there any way to add support for a HDR 3D LUT in JRVR? Or if it's already possible, how do we prevent the 3D LUT from being disabled when playing back HDR content if we load a HDR 3D LUT in the settings?

It would be a great selling point if MC was able to correct not only SDR but also HDR content.

Is no one else interested in this?

[Manni]

I found this even older thread https://yabb.jriver.com/interact/index.php/topic,132879.msg920801.html#msg920801 where Hendrik is suggesting what, in my opinion, would be the best solution for this (an entirley separate calibration for HDR output in its own section):

"I suppose it could make sense to entirely separate Calibration for HDR output in its own section, as the gamut/gamma options also don't apply to it (which isn't as much separating, but renaming the Calibration group, since HDR is not even in there yet). The HDR section could also be disabled if HDR pass-through is disabled, as in that direction it ensures that it'll never be used."

Any chance of this happening in V34?

If anyone else is interested in HDR 3D LUT support in MC when using HDR passthrough (ideally with HDR to HDR tonemapping enabled as JRVR is much better than any TV/Projector at this and if you specify the TV/PJ peak brightness it should avoid double tonemapping in most cases), please make yourself known, that might increase our chances to see this happen

If it's just me, I won't blame Hendrik / devs for thinking it can wait.

[datdude]

I'd be interested if it made a noticeable difference in the video quality. I have no clue what the real-world differences would be.

[Manni]

I'd be interested if it made a noticeable difference in the video quality. I have no clue what the real-world differences would be.

I’m only interested in real world differences

It depends on your display/projector. On my Samsung S90C (QD OLED), even after a good manual calibration using the CMS, low stimulus levels are significantly undersaturated. This doesn’t show in standard calibration reports but it’s obvious if you run saturation sweeps at 5-15% stimulus. As a result, colors are understaturated in dark scenes. A HDR 3D LUT allows to restore the proper saturation (and brightness levels) at all stimulus levels, not just at the levels the CMS works at.

This improvement is very visible, at least here. Your display could have more visible errors in other areas.
If you tried to adjust these lower stim levels with the CMS, then all the higher stim levels that would be wrong, as the CMS isn’t linear.

SDR LUTs are an option with projectors because you can get the same peak brightness in SDR and HDR, so you can tonemap to BT2020 SDR, but with most HDR TVs your peak brightness is only available in HDR. For example, I get 1,360nits in HDR but only 500nits or so in SDR, so clearly using a SDR BT2020 3D LUT doesn’t work for me.

I’m going to post some before/after measurements to show this, but it really depends on your display and on your ability to make good profiles and generate good 3D LUTs.

[datdude]

Good to know. I have an LG C1 OLED. Looking to upgrade soon hopefully. LG G5 is looking ok but has near black and gradation issues that may not be fixable. Hoping Sony releases a new QD-OLED this year that doesn't have these types of issues out of the box. If the LUT takes it to another level that would be great! I don't have the equipment or knowledge yet to create them. Is there a recommended guide on how to do so?

[Manni]

Good to know. I have an LG C1 OLED. Looking to upgrade soon hopefully. LG G5 is looking ok but has near black and gradation issues that may not be fixable. Hoping Sony releases a new QD-OLED this year that doesn't have these types of issues out of the box. If the LUT takes it to another level that would be great! I don't have the equipment or knowledge yet to create them. Is there a recommended guide on how to do so?

It looks like the more they push brightness, the more LG is causing issues in the low end sadly. Only a few more days to find out about Sony, but even if it’s QD OLED it will be limited to 77” this year. Anything above that will be WOLED, as usual. Too many downsides for me.

Re a guide, not really, LUT creation is a bit of a dark art and really depends on each display. I’ll make a how to for my S90C when I’m fully happy with the results.

EDIT: That's not what I use, but you might want to take a look at DisplayCAL, it's a free software that can be used to profile a display and generate a 3D LUT. There are many more options (Calman, Colorspace etc), but that one is free: https://displaycal.net/

[Hendrik]

I'll look into adding a HDR 3DLUT option, and leave it entirely up to the user to make sure the 3DLUT actually does something decent.

[Manni]

I'll look into adding a HDR 3DLUT option, and leave it entirely up to the user to make sure the 3DLUT actually does something decent.

That’s fantastic, thank you. Of course, it is up to the user to create a LUT that works (once the implementation is confirmed working by beta testers with experience and the ability to help you assess results and provide known good LUTs, ie LUTs in a format supported by JRiver that work fine). That’s absolutely not JRiver’s responsibility to help users in this area, especially inexperienced users. I think that’s the way it currently works with SDR 3D LUTs (which, by the way, are working great here for SDR content). It needed a bit of finetuning initially, then it was done. Of course I’m happy to help in any way that you might find useful.