3DLUT convert HDR -> SDR produces a very dark picture

[dj gigi]

Hi,

I have a Sony VW360EX projector in a room totatement black.
And I’m using MPC-BE + madVR and I have probes i1 DisplayPro + i1 Pro 2 for calibration with last version of DisplayCal (with madTPG ).

If I look at the attached Measurement Report  for the BT709 and the HDR, I get pretty good results.
But when I watch a real movie, in BT709, it’s very good, but on the other hand in HDR, it’s really very dark and too saturated

So I guess I must be doing something wrong, but I just use the setting : Video 3D LUT for madVR HDR(D65, Rec.2020 / SMTP/BT.2390) by defaut and I change in the 3D LUT setting the “target peak luminacance” to 300cd/m3 due to the low luminosity of my projector.

Do you have any idea why my image is getting so dark in HDR?

Thanks
Dj gigi

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[Florian Höch]

Hi,

the target peak luminance should be set close to your actual display peak luminance. As projectors are usually comparatively dim, this means choosing about 100 cd/m2. You may want to look at madVR’s dynamic tone mapping instead of using a HR to SDR 3D LUT.

[dj gigi]

Hi Florian,

Thank you for the recommendation to use “madVR’s dynamic tone mapping” instead.
Just to make me sure about what we’re talking, you’re advising me to use this program: madMeasureHDRDynamicOptimizer ?

On the same subject, I also noticed that madVR did not take the 3dLUT I created for HDR, at the launch of a film in HDR, I have a message in the “madVR reports” telling me that the: 3dlut file was not found.
So it loads the one for SDR….

Any idea,
Thanks

[Florian Höch]

madMeasureHDRDynamicOptimizer ?

No, just enable “let madVR do HDR tone mapping using shaderS” in madVR preferences (I’m not sure madMeasureHDRDynamicOptimizer is still needed, better ask that in a madVR-specific thread over at AVSforum or doom9).

I have a message in the “madVR reports” telling me that the: 3dlut file was not found.

Did you install it after creating it?

[dj gigi]

@Florian,

OK, thank you so much for your help

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