Grading for HDR

[Asa Shoul]

Hi all,

thought I'd get the ball rolling with this one. So, HDR, who's grading in HDR? What are you viewing on, (monitors and domestic)?How similar is it to your rec709 pass?

what are client reactions and expectations?

Thanks, Asa 

[Nicolas Hanson]

I would also like to hear about your experience with HDR. Mike Sowa shares some thoughts in this video - 

 

[Asa Shoul]

Hi Nicolas,

well he's obviously excited about it but not sure he sheds any light on his approach to grading in HDR. 

[Andy Minuth]

I can not share first hand experience, but at least some observations I made at IBC this year:

There was a panel where the technical VPs of the big studios discussed HDR and WCG (wide colour gamut). They projected some A/B examples of standard P3 digital cinema and Dolby Vision.

They told that until now, they graded the SDR main delivery first, and then asked the filmmakers and colorists to do the HDR/WCG version after that as a trim pass. They agreed, that none of the filmmakers disliked the 'bigger canvas'. But they also agreed that the filmmakers were probably less courageous with the new technology, because they already found a pleasing SDR look for their film and did not want to alter it too much. The goal should be to do the HDR/WCG version first and trim passes for the SDR deliveries.

I enjoyed the examples that they showed a lot, but I also noticed two things:

- 108 nits in the cinema is nice, but not as impressive as some people might expect. Basically it is just around one additional stop in the highlights. Way more interesting are the increased details in the shadows. 

- technical issues with the footage like noise get boosted a lot. There is definitely less range for us to deal with footage that was exposed suboptimal . DPs will have to work more precise, until the next generation of camera sensors might improve the situation again. 

 

Walking around the exhibition floor, HDR was THE THING this year. But looking at all these displays one could easily get the impression, that HDR means: an extremely saturated picture with ugly clipped highlights, that is very bright. Nice looking examples were rare.

About displays: In my opinion the Sony X300 seems to be the best choice for HDR mastering at the moment. 

 

Hope to hear about more hands-on experience in this thread...

So long, Andy

[Asa Shoul]

Very interesting Andy. Wish I could have been there. So I started an HDR pass of Ex Machina yesterday. Nice if the distributor to ask us, (Brooklyn and Victor Frankenstein were graded elsewhere and as far as I understand started from scratch). 

I started by matching the rec709 on the HDR Sony 300 but then felt that there was little point in someone buying an HDR version if it looked exactly the same, after all HDR TVs can be set to rec709. So I increased the gain to add some pop. I think you're correct that the HDR will become be the primary grade but this will only make the rec709 pass more frustrating. 

Thanks, Asa 

[Andy Minuth]

Thanks for sharing Your first experience, Asa. Yeah, I think a bit more pop makes sense, and in my opinion one of the important things about HDR is to get more definition in the specular highlights and shadows. But I guess the tricky part is that bright objects do not get too distracting. But I guess that Ex Machina with its dark and also landscape sequences will look even better. 

Are You working from your original Baselight scene, so that You can adjust the old layers? Or do You have to work with the rendered out master, which would be quite difficult I guess... ?

Edited September 29, 2016 by Andy Minuth

[Asa Shoul]

Yes going from Baselight scenes so can adjust everything. And you're so right that whilst we can have more highlight detail it can be rather distracting so I don't see us taking off too many shapes or keys just because technically we don't need them in HDR. In fact I've windowed a few more lights because they started to ping out too much. 

[Ildus gabidullin]

SGO Mistika: What is HDR

[Ildus gabidullin]

HDR Content Creation: Creative and Technical Challenges
Tania Pouli and Joshua Pines (Technicolor)

SIGRAPPH 2016 PAPER

http://taniapouli.me/wp-content/uploads/2016/08/hdr_content_creation_siggraph2016.pdf

[Bruno Mansi]

I've been to a couple of HDR demos run jointly by Filmlight and Sony at Filmlight's London office, where they demonstrated SDR and HDR side-by-side with standard monitors and the Sony X300/X550. 
The prevailing wisdom I got from these sessions was that it was not the intention to just make everything super-bright but to have the majority of the scene with similar light levels as in the past, but allow the specular highlights to exploit the display's increased brightness capabilities. Similarly, the increased colour gamut means more colours that we see in real life, but again that didn't mean we should be 'screaming' colour at the audience.

Some of the reasons for this were technical limitations. Current display technology will only allow high brightness levels over a relatively small portion of the picture to stop the panels overheating. Sony have built-in protection to clamp the brightness of the pixels if the circuitry detects conditions where this might happen, so no large swathes of sky at 800 nits!

Another issue that might effect things is colour fatigue. It's not an issue that's really been discussed, but with all these higher brightness displays coming along, what is that going to do to a Colourist's perception of hue and saturation? This was the reason some grading suites used to set their monitors to 80 nits.

Edited October 1, 2016 by Bruno Mansi

[Asa Shoul]

Hi Bruno,

yes I also has the impression that the image should look close to the rec709 with more room for highlights. Couple of things:-

Firstly when grading Ex_Machina for theatrical and rec709 I didn't go close to peak white in most situations. Like House of Cards I like a moody interior and rarely push into the top quarter of brightness unless looking into the sun. Rob Hardy has all practicals on dimmers so again interior lights aren't too bright. 

Secondly my head of Tech has had reports that as viewers often increase the contrast on their tv in rec709 but this might not be an option in HDR mode so if we've matched the rec709 for HDR it might actually look duller. 

What I'd like to do is the HDR first and see if the DP embraces the larger colour gamut and brightness. Although this will make the rec709 pass more disappointing. 

Asa 

[Thomas Singh]

Great info Asa, thank you! 

[Mark Mulcaster]

Ive done quiet a bit of testing comparing HDR (HLG) to SDR, we wanted to really get to grips with limitations or forseen problems right down from post to transmission.

The first thing we noticed that when your grading on a X300 in sdr its limited to 100nits, and so when you switch to an HDR mode you notice that increase in brightness and contrast ratio.

But what was interesting was when we were viewing the same material on consumer screens (LG) what we were somewhat confused by the lacklustre HDR we were seeing compared to a side by side SDR comparison; consumer screens don't limit their SDR to 100nits so when we measured the screen the peak brightness was 380nits , so when switching from SDR to HDR you didn' get that "wow" jump in brightness. 

This may only be a problem if theres a simulcast show where the viewer decides to jump from SDR to HDR (or vice versa) to compare the difference between the two standards.

 

From a WCG perspective we couldn't of been happier - for live sport we noticed we were seeing that overly saturated parts of the picture in 709 - which may have been clipped had the headroom to exist in the image. But when i was grading in 2020 i didn't feel the need or desire to really push the saturation that dramatically, unless the style requested it i still wanted to keep things fairly natural. But it was handy with somethings such as plants and flowers that can sometimes sit right on the edge of 709.

I will say is that when i was grading scripted drama  i found that  some highlights needed extra special attention in darker scenes they became more distracting.

Also you might want to consider lowering the luma on any captions a smidge

Edited January 4, 2017 by Mark

[Asa Shoul]

Hi Mark,

very interesting about the luminance on domestic sets not being limited to 100nits. Our head of tech mentioned that he's heard from consumers that because you can adjust contrast and brightness on domestic TVs in SDR but not when set to HDR mode, the HDR can appear duller than the SDR grade. I was recently sent examples of 4 feature films from a major studio in both SDR and HDR and was shocked at how far they are pushing the HDR. Rather than simply matching the SDR and using the extra headroom for  the highlights they were brightening the whole image so that highlights were around 80-90% of the 1000nits. Even night scenes were pushed extremely bright. 

What's your grading platform?

Many thanks, Asa 

[Mark Mulcaster]

 

Thats it exactly Asa,  at least with the firmware builds we've been testing hdr on the consumer screens are limited to the settings you can change, the "Cinema" mode seemed to be the default which i suppose makes sense,

I was in another facility last week where they were looking at a SDR - HDR conversion and seeing where the pit falls were for doing something like this on a existing delivered master.

We spent some time going through some scenes and found that the most important thing is not straying to far from the intended artistic intent. 

So whilst we the test clips we were playing in were converted from 709 to 2020 we matched the saturation and let the HDR follow a similar route.

We chose not to push everything just because we could, but instead let it sit naturally and compliment the look and style of the test clips, whilst at the same time expanded the speculars.

Its worth noting that the clips we looked at were shot and graded beautifully so we didn't have to deal with issues of clipping or crushing.

It was an interesting test to see from a broadcast perspective if a HDR service could be complimented with SDR material rather than having to exclusively request HDR programming and commercials for example

Our internal testing was mainly been  on Mistika due the benefits of its open time and robust toolset, we're now also looking at HDR on Basleight.