Mark Mulcaster

HDR Grading - Colour Reproduction on monitors

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I'm about to grade some musical performances in HDR - The deliverable will be a HDR10 1000nits @D65.

I've have been advised to set my Sony BVM X300 monitor set to P3 rather than the full rec2020 gamut setting as the majority of consumer screens aren’t likely to reach %100 Rec2020 but P3 is far more achievable by a larger cross section of consumer TVs, if i recall my Sony X300 doesn't even cover the full rec2020 colourspace.

Is this generally the accepted approach to take for HDR?

From alot of the HDR content i've seen (not including TV manufacture demos) the image saturation for HDR doesn't feel hugely more saturated from SDR, preconception-ally speaking. 

So other than dealing with some very saturated stage lighting i don't see this being a major concern?

Looking at my Baselight cursor options I don't have a PQ/P3/100nits cursor on my Baselight. 

 So keeping with the  ST2084/PQ/REC2020/1000nits viewing cursor i switched the monitor into P3 and noticed a slight hue shift in my monitor on the test footage.

Before i bother the lovely filmlight support team and rasie a ticket i wanted to ask if i need to, or just stick to rec2020 and be mindful of any highly saturated parts of the image?

 

Thanks

Edited by Mark

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Hi Mark,

You should avoid a mismatch of Viewing Colour Space in BL and the settings of your display. Otherwise your renders will look wrong. Actually there is no need in BL to set your viewing colour space to P3 gamut while grading in your case, but if you want to do it, then please use the 'Dolby: ST 2084 PQ / P3 D65 / 1000 nits' colour space for viewing.

Alternatively set your viewing colour space to 'Rec.2020: ST 2084 PQ / Rec.2020 / 1000 nits' and the X300 accordingly. Please verify then in the Colour Space Journey that your Mastering Colour Space is 'Dolby: ST 2084 PQ / P3 D65 / 1000 nits'. It will limit your output to P3 gamut. Just try to see Rec.2020 as a container gamut, compareable to X'Y'Z'.

And as a sidenote: Please use the 709 colour matrix in the X300 in both cases. In BL 5.2 there will be an option to change the colour matrix for the RGB -> Y'CbCr conversion, but until 5.1 the 709 matrix is used.

Cheers, Andy

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Thanks Andy,

 

16 hours ago, Andy Minuth said:

Alternatively set your viewing colour space to 'Rec.2020: ST 2084 PQ / Rec.2020 / 1000 nits' and the X300 accordingly. Please verify then in the Colour Space Journey that your Mastering Colour Space is 'Dolby: ST 2084 PQ / P3 D65 / 1000 nits'. It will limit your output to P3 gamut. Just try to see Rec.2020 as a container gamut, compareable to X'Y'Z'.

 

Putting it like that makes a lot more sense, i think i was approaching it from the wrong perspective, it makes sense about seeing the Rec2020 as a container. 

I'll have to look for  the Dolby: ST 2084 PQ / P3 D65 / 1000 nits viewing option as from what i recall when i wrote my original post i didn't see it listed in my Baselight (we're running 5.1).

My thought about grading in PQ/P3 was to play it safe a bit and make sure  i wasn't grading any colours out of gamut that my monitor wasn't able to reproduce correctly, or that when the content hits the consumer screens.

It may not be necessary but i wanted to try both approaches to see for myself.

Ever so quickly what does the transfer matrix do on the X300? I've toggled it on and off but didn't see any difference to the image on screen.

 

8 hours ago, Marc Wielage said:

Some good reference material here:

"Dolby Vision Color Grading Best Practices Guide 2018"

http://www.digitalvision.tv/w/images/d/de/Dolby_Vision_Color_Grading_Best_Practices_Guide_2018.pdf

I also have collated a few HDR/Rec 2020/Rec 2100 documents relating to post-production which are at this download link:

https://spaces.hightail.com/space/nEaXy

 

Thanks a lot for the links Marc!  Thats really very helpful, theres alot of reading there....does it come in audiobook form 😉 

 

Many thanks

-Mark

 

Edited by Mark

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On 12/8/2018 at 3:28 PM, Mark said:

My thought about grading in PQ/P3 was to play it safe a bit and make sure  i wasn't grading any colours out of gamut that my monitor wasn't able to reproduce correctly, or that when the content hits the consumer screens.

The Mastering Colour Space in BL is taking care of that. It clips all values outside of it and ensures that you don't render anythink into your master that you haven't seen while grading.

 

The matrix takes care of the conversion from Y'CbCr to RGB and back. When you are driving the display in 4:2:2 this becomes relevant. The differences between the 709 and 2020 matrix are not that big, but saturated colours might shift slightly in hue.

Cheers, Andy

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Hello @Andy Minuth! I also had a question about HDR in Baselight , I was at a seminar in Moscow and was glad to get to know you.
I can’t understand how to configure the BS 5.2 for the operation of  HDR, I also have a 100 NIT indicator in Luma Waveform, and the cursor is set to REC 2020: 600 nits, my LG С8 monitor is calibrated for HDR, I definitely think that I’m missing somewhere. I understand that I have to translate Luma Wave in a state of up to 10,000 nits, according to screenshot 4, why can't I? 

Thank's :) 

1.jpg

2.jpg

3.jpg

4.jpg

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Hil Ilya,

this is because of the selected DRT ACES RRT 0.1.1. This DRT only outputs SDR. You need to select one of the family DRTs (ACES 1.0.1, TruelightCAM, etc.) for HDR output.

Also I don't recmommend to use ACEScc. Better to go with ACEScct as a working space. When you create a new scene my advise is to use either the ACES or Filmlight template. That will setup everything correct for SDR and HDR.

Cheers, Andy

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Usually I grade in SDR in ACES workflow. And I keep my viewing colour space ACES : Cineon Log / APO. But after this article read I just test the those theree type of viewing colour space ,

1) ACEScc : ACEScc / AP1

2) ACEScct : ACEScct / AP1

3)ACES : Cineon Log / APO

I feel when I import Arri mov. rush in Cineon Log it's giving some clipping highlights than the other two and also in Cineon Log when I saturated too much it's became pixlete colour but the other two are not giving .

I also want to know difference between the 

REC.2020:ST 2084PQ/Rec.2020/108nit

REC.2020:ST 2084PQ/Rec.2020/600nit

REC.2020:ST 2084PQ/Rec.2020/1000nit

REC.2020:ST 2084PQ/Rec.2020/2000nits

REC.2020:ST 2084PQ/Rec.2020/4000nits

And when they use. Which viewing and mastering option  is correct for HDR10 and Dolby Vision Grade

 

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On 7/4/2019 at 9:09 AM, Soumitra Sarkar said:

Usually I grade in SDR in ACES workflow. And I keep my viewing colour space ACES : Cineon Log / APO. But after this article read I just test the those theree type of viewing colour space ,

1) ACEScc : ACEScc / AP1

2) ACEScct : ACEScct / AP1

3)ACES : Cineon Log / APO

I feel when I import Arri mov. rush in Cineon Log it's giving some clipping highlights than the other two and also in Cineon Log when I saturated too much it's became pixlete colour but the other two are not giving .

Hi Soumitra,

for ACES workflows I recommend to use 2) ACEScct : ACEScct / AP1 as working colour space. The Cineon Log curve does not have as much headroom in the highlights and if you are clamping to 0..1 range in an operator you might loose information there.

On 7/4/2019 at 9:09 AM, Soumitra Sarkar said:

I also want to know difference between the 

REC.2020:ST 2084PQ/Rec.2020/108nit

REC.2020:ST 2084PQ/Rec.2020/600nit

REC.2020:ST 2084PQ/Rec.2020/1000nit

REC.2020:ST 2084PQ/Rec.2020/2000nits

REC.2020:ST 2084PQ/Rec.2020/4000nits

The different nit levels will change the highlight roll-off in the DRT and the Mastering Colour Space. When you select REC.2020:ST 2084PQ/Rec.2020/600nit as viewing or render colour space, highlights will smoothly roll-off to 600nits peak, and the Mastering Colour Space will ensure wird hard-clipping, that there are no values above in the output.

On 7/4/2019 at 9:09 AM, Soumitra Sarkar said:

And when they use. Which viewing and mastering option  is correct for HDR10 and Dolby Vision Grade

That depends on the display you mastered on and the delivery specs. But typically people use REC.2020:ST 2084PQ/Rec.2020/1000nit as an output for HDR10 with Dolby: ST 2084 PQ / P3 D65 / 1000nits as Mastering colour space (to limit everything to P3 gamut).

For Dolby Vision 'Dolby: ST 2084 PQ / P3 D65 / 1000nits' is used a lot as 'Dolby Vision Mastering Colour Space'. We have a special Dolby Vision chapter in the Baselight user guide that I recommend to work through. You can download that chapter separately from our Webpage: http://filmlight.ltd.uk/support/documents/baselight/manuals_bl.php 

Cheers, Andy

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