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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