Grading HLG BT2020

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Yogendra Singh

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Grading HLG BT2020

PostMon Aug 20, 2018 7:18 pm

Guys,
Is there anyway I can utilise the full dynamic range of HLG format shot on a7III in BT2020. The possible color space transformation tips if you can give that would be great. TIA
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Andrew Kolakowski

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Re: Grading HLG BT2020

PostMon Aug 20, 2018 7:43 pm

There is no special approach needed. You just grade from source to HLG calibrated screen. That's it.
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Yogendra Singh

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Re: Grading HLG BT2020

PostMon Aug 20, 2018 8:04 pm

Andrew Kolakowski wrote:There is no special approach needed. You just grade from source to HLG calibrated screen. That's it.

So can it be made to view on a normal TV without clipping details?
Last edited by Yogendra Singh on Tue Aug 21, 2018 1:15 am, edited 1 time in total.
https://www.instagram.com/weddings_by_yogendra/
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Andrew Kolakowski

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Re: Grading HLG BT2020

PostMon Aug 20, 2018 11:30 pm

Don't understand your question.
You said you want to grade to HLG HDR.
If you have no HDR TV then forget about HDR and work in Rec.709.

If you then want HLG convert to Rec.709 then you can. Just adjust it. HLG will look dull (bit dark) on SDR screen without any processing.
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Yogendra Singh

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Re: Grading HLG BT2020

PostTue Aug 21, 2018 1:53 am

Yes, I would like to convert it to rec 709 so that it can run on normal LED TVs with its complete dynamic range.
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Dermot Shane

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Re: Grading HLG BT2020

PostTue Aug 21, 2018 3:20 am

709's dynamic range and gamut are both far smaller than a modern camera can capture, or that negitive film could capture decades ago

there is tone mapping to convert HDR to SDR, to my mind, best thought of as a starting place for creative choices, not a final destnation
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Cary Knoop

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Re: Grading HLG BT2020

PostTue Aug 21, 2018 4:09 am

You could set up an HLG to Rec709 workflow like this:

settings-hlg.jpg
settings-hlg.jpg (69.72 KiB) Viewed 413 times


The timeline gamma above is a log format, it is not essential to the result but depends on how you want the controls to work, you could for instance also use Rec709.

After this, you should map the wider dynamic range onto Rec709, Resolve also has tone mapping functionality but it is an auto mode, better to do it by hand to see what looks give based on the type of footage, exposure etc.
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Andrew Kolakowski

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Re: Grading HLG BT2020

PostTue Aug 21, 2018 9:35 am

This is more for case when you already have HLG master and want to do Rec.709 one.

If you're starting from scratch with Sony source files you don't do such a thing. You either set Resolve for HLG or Rec.709. If you don't have HLG decent monitoring then your only option is Rec.709.

I really don't understand what Yogendra is trying to do.
He wants to get most of the source as HLG Rec.2020, but then he is talking about watching it on SDR monitor.
If you want perfect solution you simply need to do 2 masters HDR and SDR one.
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Martin Heffels

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Re: Grading HLG BT2020

PostTue Aug 21, 2018 10:16 am

Andrew Kolakowski wrote:I really don't understand what Yogendra is trying to do.
He wants to get most of the source as HLG Rec.2020, but then he is talking about watching it on SDR monitor.


HLG is being experimented with as an alternative to S-Log/S-Log2/S-Log3, because it isn't as squeezed in the bitrate, and allows lower ISO.

I played around with it a bit, grading it down to Rec.709, and I find the end-result a bit more pleasing than with S-Log. For instance the skies stay blue, while on S-Log I find it has this odd Sony cyan-look.
I haven't found the ideal recipe yet, but I use ACES with an output transform to Rec.709 and set ACES Input Transform of the individual clips to Rec.2020 (Camera), and go from there.
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Andrew Kolakowski

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Re: Grading HLG BT2020

PostTue Aug 21, 2018 10:36 am

Well, now I understand original question properly :D
Oh well- still can't read English sometime.

Source is HLG Rec.2020 and destination just SDR. Is there a special approach? You just grade it to look which you like. You may use ACES or mentioned Cary's method. I don't know what gives you better start, you need to experiment. You definitely can get good result without any clipping. You will have to make artistic decision how data is spread in highlights, bu this is nothing special. Rec.709 is forcing you to squeeze all source data, but because source has much more data you can make those artistic decision ( this is why you want to shot in HLG or SLOG- to have more data to play with).
Funny enough, but according to Alister Chapman you should not use HLG as source for grading. It meant to be "final" signal, like Rec.709 for SDR is:
http://www.xdcam-user.com/2017/07/what- ... -used-for/

I assume when you start adjusting HLG for HDR output then you will quickly see that there is not much data to play with (like with REc.709 for SDR), but when you going down to SDR maybe it's good data to work with (alternative to SLOG). I've seen few people saying this.
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Cary Knoop

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Re: Grading HLG BT2020

PostTue Aug 21, 2018 2:36 pm

Andrew Kolakowski wrote:You may use ACES or mentioned Cary's method.

Unfortunately, you cannot currently use ACES with Resolve because Resolve has not updated to ACES 1.1.

Something that is rather puzzling to me since Blackmagic had plenty of time to put in ACES 1.1 for Release 15.
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Andrew Kolakowski

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Re: Grading HLG BT2020

PostTue Aug 21, 2018 3:24 pm

Also- Resolver doesn't have any ACES Input Device Transform for HLG shot content at all.
Whole ACES is nice on paper, in reality it's still problematic mainly due to IDTs, which apparently is key element.
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Cary Knoop

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Re: Grading HLG BT2020

PostTue Aug 21, 2018 3:28 pm

Andrew Kolakowski wrote:Also- Resolver doesn't have any ACES Input Device Transform for HLG shot content at all.

It will be in ACES 1.1.

HDR has improved in 1.1 (read: HDR in ACES 1.0 was not all that).

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