Movie project in ACES from HDR PQ to DCI

Discussions - Using ACES Post (DI, Edit, Mastering)
#1

Hi, I have a project that we have mastered on a HDR PQ 2084 1000NIT Display in Resolve for future HDR distribution. I wanted to find the best path to trim and render out a version of the movie in DCI P3 for a cinema release. I hoped that this will be an easy process similar to Dolby Vision workflow in to Rec 709. And for me clearly it is not. However I am unsure if Im doing things the way I should. Is there a tested way to do this correctly.
PS. I do have a display which is calibrated for P3 in 65nits.

Kinderst regards,

Andrzej.

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#2

Hi Andrzej and welcome to ACESCentral.

I’m sure someone from the community will answer this, and I’ll check back to get you some help if not.

Best,
Steve
ACESCentral Admin

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#3

I don’t think anyone is too keen to answer :slight_smile: I started looking at the ACES groups and meetings. I see there is a ACES ODT development group as well as ACES Gammut Maping. However I find it hard to belive that this is an uncommon problem, and that it hasn’t been solved yet. Im sure someone has stumbled upon this issue and tried not to do 2 separate runs on Color Grading. I find the Dolby Vision shot analysis very clever indeed and would think that a similar process should be replicable in ACES workflow. And if not, then even a set of trimming tools dedicated to the process would be an amazing option.

Hope to hear from someone :slight_smile:
Andrzej Niski

#4

I do this all the time in resolve.

  1. Do primary grade (usually ST2084 1000)
  2. Duplicate timeline for Rec709 or DCI-P3 and set ODT to corresponding output
  3. Make a global correction for lower dynamic range. Like a highlight roll off or global contrast adjustment
  4. Go through the feature and adjust the shots or scenes that need work.

The amount of shot adjustments depends on the project. It is usually scene adjustments more than shot adjustments. A lot of the time just changing the ODT and then tweaking the highlight rolloff for the new range is enough. It just depends on how much of your image lives close to your 1000 nit limit.

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#5

Thanks Elvis for your reply,
I thought that you guys might have a way of automatically or semi-automatically assessing the exposition and latitude of a shot and than using that information to adjust the image before it comes out to the ODT. I was really impressed by what the Dolby Vision workflow does, and thought that maybe there is something that uses the ACES mathematics along the same lines. Or maybe there are trimming tools within the aces workflow which would not involve making nodes and normal grading work but just adjusting the way that the ODT outputs the final image. Sorry if it doesn’t make a lot of sense, Im pretty new to the ACES workflow. II am a big ACES fan by the way, and think that this is all very clever :wink:
Thanks again!

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#6

Thanks Elvis for stepping up :slight_smile:

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#7

Yeah that is the Dolby secret sauce to adjust image and trim levels for lots of outputs and embedding them in the master.

But if you are just doing an HDR grade and then wanting to make a P3 version in practical terms it works the same with the Dolby analysis. The output transforms for each display type do work pretty well. If you make an adjustment to make HDR look like you want it usually still is close in SDR.