Sdr -> hdr?

[cubicibo]

At the end of the day, what you're trying to do is generally not useful. There's just no "data" in your source to justify expanding it to HDR without creating ugly artifacts. In general, SDR content presented on UHD BD is delivered as SDR bt709 or SDR bt2020. Most SDR content presented in HDR bt2020 generally remain in SDR levels, with a very occasional leak in some direction of the gamut. This "leak" in HDR domain is can be the result of manual tuning by the video engineer/colourist, but often it comes solely from compression noise!

[Blue_MiSfit]

> SDR content presented on UHD BD is delivered as SDR bt709 or SDR bt2020

Is there any SDR BT. 2020 content distributed anywhere? On UHD BD or otherwise? I've never seen any.

[cubicibo]

JP BD of Evangelion 3.333 advertises itself as SDR bt2020.

映像の規格は、通常のテレビ放送用などで使われるSDR(スタンダードダイナミックレンジ（※１）)としていますが、その色域は、通常のHD放送規格のBT.709（※２）より広い、UHD規格であるBT.2020（※３）を使用致しました。
== (GTranslate) ==>
The video standard is SDR (Standard Dynamic Range (※1)), which is used for regular TV broadcasting, but the color gamut is BT.2020 (※3), a UHD standard that is wider than the regular HD broadcast standard BT.709 (※2).

The british Millenium Actress UHD BD is bt709 SDR.

[FranceBB]

Originally Posted by Blue_MiSfit

Is there any SDR BT. 2020 content distributed anywhere?

Anything that ever aired on linear TV from 2015 to 2017. Then in 2018 HDR HLG arrived to save the day without screwing users over. Almost every sport event broadcasted in that timeframe was BT2020 SDR 100 nits.

[Blue_MiSfit]

...Really? Sports in this timeframe were not delivered in regular SDR BT. 709? Where? I've literally never heard this, even from a close friend who was working for a major regional sports network here in Los Angeles.

When you mean it was BT. 2020 SDR - do you mean perhaps some colors were allowed outside of BT. 709 gamut, or are you suggesting that the camera shading was actually using BT. 2020 primaries and pushed well outside of the 709 gamut for creative intent?? If so, was that actually signaled on the compressed live feed or was it masquerading as BT. 709 primaries?

[FranceBB]

Back then it was all really new and really entertaining. It wasn't just live sports but also things like documentaries etc. Cameras were all set to shoot with their proprietary gamut. For instance, Sony cameras were set to record in S-Gamut3 and were then converted to BT2020. For reference, BT709 covers 35% of CIE 1931, S-Gamut3 covers 53% and BT2020 covers 75%, so back then you had something better than BT709 (i.e S-Gamut3) converted to BT2020 which yield better results. When HDR HLG arrived, the same cameras were then used to produce HDR despite not being able to shoot directly in HLG by combining S-Gamut3 with Slog3 which is a totally logarithmic transfer and allowed people to output BT2020 HLG after going through an RGBPS 16bit roundtrip. It was all a bit hacky with many things that could go wrong, but it worked, at least in Europe.

[benwaggoner]

There's no way to do HDR from SDR that would approach the creative intent of a colorist doing the HDR. as there are many, many ways to do that conversion. And the sources used for the remastering are often ACES, DCP, or other > Rec.709 color volume, so there are more highlights to preserve.

Good ML software that can be given patience and lots of lookahead should be able to outperform what a TV can do in realtime, though.

[asarian]

Originally Posted by benwaggoner

There's no way to do HDR from SDR that would approach the creative intent of a colorist doing the HDR. as there are many, many ways to do that conversion. And the sources used for the remastering are often ACES, DCP, or other > Rec.709 color volume, so there are more highlights to preserve

Nevertheless, I am very happy with what FranceBB did with his LUTs.

[FranceBB]

Well, both the BT709 to BT2020 HLG and BT2020 PQ LUTs were made to target 400 nits which is a very good compromise when it comes to SDR converted to HDR.
Those were tested on a Sony BVM-HX310 reference monitor which peaks at 1000 nits and is connected to a Tektronix Waveform Monitor.
The original reason behind those LUTs was to make life easier for those who wanted to include legacy SDR contents into native HDR ones without having any issues.

First use case:

The first use case was documentaries in which you had interviews shot in Slog3 that could be graded to HLG of the person interviewed, of the surroundings etc and at the same time you had legacy footage of that person that you had to include. One such a documentary was "A proposito di Max" which even has scenes in BT601 SDR which were first converted to BT709 SDR and then to BT2020 HLG HDR. Another one was "Leo sulla cresta dell'onda" as it also included some clips recorded by Leonardo Fioravanti himself using his phone as he was traveling around the world and were clearly in BT709 SDR. Another one is "Ljubo" which is a documentary about the very famous tennis player Ljubicic which again included legacy footage.

Second use case:

Obviously documentaries are just one of the use cases of converting BT709 SDR to BT2020 HLG HDR or BT2020 PQ HDR, another one can be live feeds. For instance, take F1. The feed is delivered by Tata (the official producer) in BT2020 HLG HDR to all the licensors around the world and while some TVs just limit themselves to put the commentary on via a speaker boot, plenty of others go above and beyond to send their own journalists to follow the races across the world, interview pilots etc. Most often than not, those interviews are live and sent back in H.265 with a short delay via IP (i.e internet) using applications like LiveU or using satellites like Elpitel, but due to constraints those cameras are almost always BT709 SDR. So... what do you do? Well, you have the whole race in BT2020 HLG HDR at 1000 nits and then you have the interviews in BT709 SDR converted to BT2020 HLG HDR on the fly. Given the very limited nature of BT709 SDR and its 100 nits corresponding to around 6 stops in a camera (a modern HDR camera can record 15 stops) and the very challenging environment, you may end up with clipping in SDR, so the last thing you wanna do is bring that clipped out white sky from 100 nits to 1000 nits as it would burn your eyes (well, not literally, but it will give you a very unpleasant feeling). Hence, the 400 nits target in my LUTs which should accommodate for any challenging shot as a pure white at 400 nits is still very much tolerable.

Third use case:

The last scenario I wanna depict here is commercials. You see, there are plenty of linear channels and all of those broadcast at a certain native resolution. Nowadays, it's not uncommon to have the very same channel in SD (BT601 SDR), FULL HD (BT709 SDR) and UHD (which used to be BT2020 SDR and evolved into BT2020 HLG HDR for backwards compatibility). In those channels, everything must be consistent, not just the shows (i.e tv series, movies etc), but also all the commercials, so, just like FULL HD BT709 SDR commercials are downscaled to SD and converted to BT601 SDR, they're also upscaled to UHD and converted to BT2020 HLG HDR.

[benwaggoner]

Originally Posted by asarian

Nevertheless, I am very happy with what FranceBB did with his LUTs.

Yeah. And starting with HLG gives a lot more information that good old 709.

[asarian]

Originally Posted by benwaggoner

Yeah. And starting with HLG gives a lot more information that good old 709.

Sarcsasm? Anyway, I see SDR2HDR like upscaling: you can't really squeeze more definition (pixels) out of the original than it came with; doesn't mean you cannot repair/interpolate things, and thus (sometimes drastically) improve picture quality. Same with SDR2HDR: FranceBB cannot apply highlights/accent the way a creative director would (we'd need some real A.i for that, like twenty years down the line). Still, the result is pretty impressive, and I prefer the result over plain SDR.

[RanmaCanada]

Originally Posted by asarian

I don't have thousand of dollars available for professional software like that. Instead I rely in the generosity of people like FranceBB, to make these LUTs available for free!

I know this is really late, but Davinci Resolve Studio is $300 USD.

[benwaggoner]

Originally Posted by cubicibo

JP BD of Evangelion 3.333 advertises itself as SDR bt2020.

This would be for just the 4K HDR Blu-ray Disc, not the OG BD disc. There's no support for anything beyond 8-bit Rec. 709 in the original BD.

SDR WCG kinda makes sense for remastered anime, which generally doesn't have a lot of contrast, but can be very colorful.

[benwaggoner]

Originally Posted by asarian

Sarcsasm? Anyway, I see SDR2HDR like upscaling: you can't really squeeze more definition (pixels) out of the original than it came with; doesn't mean you cannot repair/interpolate things, and thus (sometimes drastically) improve picture quality. Same with SDR2HDR: FranceBB cannot apply highlights/accent the way a creative director would (we'd need some real A.i for that, like twenty years down the line). Still, the result is pretty impressive, and I prefer the result over plain SDR.

Technicolor has demoed some pretty good AI SDR to HDR conversion that's trained on how a bunch of great colorists did SDR to HDR remasters. Still not how a specific colorist might decide to regrade a specific title, lacking any sense of creative intent. But definitely better than a fixed LUT, and often better than algorithmic adaptive LUTs like ColorFront's. But of course, with a risk of doing something hallucinatory.

The best quality solution I've worked with that is extremely reliable is ColorFront's. Regularly superior to any fixed LUT.

[asarian]

Originally Posted by RanmaCanada

I know this is really late, but Davinci Resolve Studio is $300 USD.

Yeah, I saw. Waiting for a possible Black Friday deal.

[Leo 69]

Here's a tutorial on how to to SDR=>HDR conversions on NVIDIA cards (using only free software).

[benwaggoner]

Originally Posted by Leo 69

Here's a tutorial on how to to SDR=>HDR conversions on NVIDIA cards (using only free software).

So it just uses the Nvidia TrueHDR algorithms? Are those good for natural images? There's not much info on how they work, and they sound to be game-focused, not TV/movie content.

[Z2697]

Originally Posted by benwaggoner

So it just uses the Nvidia TrueHDR algorithms? Are those good for natural images? There's not much info on how they work, and they sound to be game-focused, not TV/movie content.

They are both game and TV focused, but the result is not really great.