MadVR HDR and Dolby Vision 4000 Nits PQ Tonemapping Tutorial

madvr hdr tutorial dolby vision

There are some HDR aspects that you must learn before playing a movie on your devices/screens.

HDR is a higher nit grade in the PQ Gamma BT. 2020 space for Blu-Ray and our transfers in UHD VISIONPLUSHDR-X.

There are low nit Max-Fall grades ( 1000 nit PQ HDR ) that most studios decide to do with the goal to avoid difficulties in the tonemapping.

Most HDR10 TV’s tonemapping and compression capabilities are not that good.

Dolby Vision TV’s will compress and tonemap in a higher quality level if the video is flagged with the Dolby Vision package only.

If not DV flagged, it will just playback with HDR10 “features”, in case of a Dolby Vision TV set, it won’t use the Dolby chipset for tonemapping.

Most HDR10 movies use low MaxFall and low peak to avoid HDR10 TV’s to show a wrong tonemap and clipped details with compressed gamut.

Being low nit, the tonemap will be almost not used therefore will look just good and how the director and colorists wants.

It’s also easier to grade to a low nit Max-Fall, and most of times a Re-Grade is not even performed.

Re-Grading HDR involves optimizing the PQ gamma curve for the real HDR potential and effect.

An HDR Re-Grade will enhance the highlight detail and deep blacks but at the same time expanding the range and contrast in a balanced output image.

This creates the feeling of watching a realistic image unlike SDR standard where everything is just linear and limited to the 100 nits gamma curve.

How to playback 4000 nit Re-Grades properly

As now we use YouTube HDR to showcase our work, some people without HDR capable screens or YouTube HDR support will see a basic tonemapped version in SDR levels.
Despite YouTube SDR tonemap will be always better than the actual SDR movie, the HDR is way richer in any aspect.

The only way to playback 4000 nit HDR Re-Grades on a computer is by using MadVR “HDR to SDR” function.

Don’t pay attention to the “HDR to SDR” phrase, this is just how Madshi ( the MadVR creator ) called this function, the output will be always a tonemapped native HDR image, exactly as any HDR TV do with all studio HDR Blu-rays.

HDR in screenshots more when 4000 nits grades with 400 to 700 max-fall are hard to represent.
So we will just try to explain and showcase HDR in a better way than any other place using images tonemapped by MadVR.

As explained, a tonemap is a way to represent the HDR image on a screen with less nits than the graded video.

Dolby Vision itself is a set of tonemapped SDR information put on a metadata to allow the HDR10 track be enjoyed in a better tonemapped version than using the static option.

The colorists and director choose how the tonemap should look by specific scenes or frame by frame. That’s Dolby Vision package, the same HDR10 track with customized tonemapping injected by proprietary metadata information.

The Dolby Vision “effect” can also be done without the Dolby Vision package, but this won’t be discussed today.

MadVR can represent different tonemaps if you just touch the settings in the HDR to SDR function.

 

Examples of MadVR tonemapping:

Source: Our UHD VISIONPLUSHDR-X The Avengers 2012

The SDR Blu-Ray:

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MadVR HDR to SDR using 400 nits, 70% preserve hue and 100 nit diffuse white. Highlights are uncompressed.
You can clearly notice the HDR image in comparison to the SDR version.

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Now we have used a 600 nit HDR to SDR tonemap with preserve hue off and 100 nit diffuse white.
The output will need a panel capable to showcase the 600 nit processed image. Otherwise would look darker.
In case you are using a pc monitor or smartphone panel with lower nits, you could rise your brightness if needed.

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And now the first MadVR Easy option called “Let Decide”. This option basically goes back to SDR from an HDR source, 200 nit processing with compressed highlights and gamut:
It kills the highlight white, but it will look really close to the SDR version, with a little better contrast.

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Some more examples from SDR vs HDR MadVR 400 nit tonemap:

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Source: Our UHD VISIONPLUSHDR-X Indiana Jones and the Temple of Doom

The next 2 images are using MadVR’s tonemap HDR to SDR option in 475 nits,
50% preserve hue and 100 nit diffuse white.
The highlights are uncompressed to properly show the HDR contrast ( clipping may occur ).

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Now this set of images use 600 nit instead and the same rest of the settings as above setup.
This way you will see what a higher Max-fall grade can do in a movie.

Note how highlights shows more detail and looks more realistic, this is because the grade got a higher Max-fall than most studio 1000 nit HDR grades.
Not only the highlights look more detailed, but the blacks are deeper, the gamut is higher and cleaner thanks to the optimized PQ Curve.
The HDR contrast (mostly called HDR-Effect) is also higher.

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Only downside when watching high nit processed images is that you need a panel with such nits to fully enjoy it. Or you will feel it dark.
MadVR has a first option in the HDR functions called “Let Decide”, this option basically do a 200 nit compressed highlights tonemap.
We don’t recommend using this option as it goes too much back to SDR levels and it kills the highlight detail.
It also generates the gamut to be compressed.

For 4000 nit grades, MadVR HDR to SDR in high nit processing is always recommended.

Never use VLC 3.0 or any other such Windows 10 HDR Movies & TV player, as those are meant for 1000 nit HDR grades.

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