SDR To HDR Part 2 – Working With Graphics In Node-Level Color Management

So just to be clear, the big benefit of using the CST instead of the ACES transform for graphics is to be able to limit the max nit value of the whitepoint?

Yea – but you aren’t limiting it so much as setting it. It doesn’t clip – it just lets you say how high to map the peak whites in the gamma 2.4 image into PQ.

The same workflow would be totally fine with ACES transforms and then again adjusting gain to taste on the clip level – but I like a bit of precision to start with, and the CST’s additional options give that.

Fantastic Joey. My XM arrives soon and I will revisit this for sure. I had a couple questions.

1. When expanding graphics from .rec 709 into a larger color space/gamma, is there ever a concern about quality loss? You’ve got relatively simple, small white graphics here, but when there’s more color involved and graphics are more of a part of the shot, does that become a concern?
2. On a similar note, any thoughts/tutorials that I can share with other team members about building more HDR-compliant graphics? They’re already adept at using OCIO in AE; are there formats/best practices for them?
3. Watching this made me wonder if HDR opens a whole new can of worms for the colorist to become the finishing person at smaller shops. Since, I am the only one with the HDR monitor, now I am responsible for graphics, re-conform and probably audio, deliverables, QC and everything else. The days of me delivering a pile of clips to an editor to do all that finishing work is over now, isn’t it? 😉

Brian Singler

Hey Brian!

As far as graphics go – yes the brighter you go there are some concerns. The higher nit values in PQ have progressively less and less code values available – so if you were getting to seriously bright graphics, you can run into issues with banding as the precision available to them gets less and less. This usually won’t happen though since you aren’t likely to see graphics that far up the curve – but it’s definitely something to be aware of.

Another thing to be aware of and think about is how gradients/edges/etc look with the background footage. This can make for some interesting creative challenges with competing colors in the image and the graphic – but it really is a case by case thing. As with many aspects in HDR – I don’t think there is a hard and fast rule.

For making HDR graphics – I think its a bit of a double edged sword having them designed/originated in HDR. It is great for giving the artist more creative room to work with – and more control over the final color in the graphics, but for it to be worth the effort – they would need good, calibrated HDR monitoring. I would say if they have that – by all means have them use OCIO and originate graphics in HDR. Then you won’t need to touch them in the grade.

But if they are using SDR monitoring, or consumer level HDR monitoring? I think its best they stay in Rec709 where they can be confident in the calibration – as opposed to building graphics they don’t have the monitoring to actually view (which could introduce a ton of problems down the line).

As for the role of the colorist – I think you’re absolutely right. In HDR its essential the entire project gets finished, viewed, and QC’d/evaluated on reference level monitoring. If the colorist is the only person in the facility with that equipment – they are going to need to be more involved in that process. Maybe not doing everything – but certainly watching down and verifying everything.