Good Ideas? The HDR Palette One Year Later & Selling Your Project Files

I found the discussion around exposure, grey point, and the HDR tool extremely interesting, as it related to my own perspective with grading footage. Establishing a “standard” grey point, relative to the original exposure choices, the OETF conversion, and the final intent becomes a “chore” for all  my footage. I, sincerely, wish Blackmagic could “standardize” the HDR tool to a reference grey point standard. I recognize the difficulty with that, but, perhaps it should be related to each camera characteristics, much like the camera’s native DRT is.

Starting to wonder what the 3 dot colors space and color gamma assignment does to the HDR controls.
I thought before watching this that it would take the manufactures middle grey as a set point. But after watching this I tested it and changing from one LOG to another with that menu all the zones stayed the same but the histogram trace moved.
Is there any sure way to test exactly what it does changing it there?

Sharing a quick experiment: attached are screen grabs showing how the HDR Palette is plotting mid gray and the surrounding zones with three different mid gray cards: one for ACEScct, one for LogC, and one for Davinci Intermediate. In each case, Timeline Color Space was set to match that of the gray card being used.

So which one is which? There’s no way to tell, because the results are identical, which is what I’d expect. While this quick test doesn’t rule out the possibility of localized bugs, it’s clear that the intended (and actual) behavior is exactly what we’re asking for in this thread: middle gray being defined by the declared color space, and the zones being drawn relative to that point.

Hey Cullen….

I can confirm what you’re demonstrating. Now, let me ask a question that confuses me. Instead of using the three dot menu, add a CST node converting the 709 grey card to the T/L space, say Davinci Wide Gamut. In order to get the grey card to align with ‘0’ on the HDR display, I have to turn off tone mapping, saturation mapping and EOTF. This implies that in order to get a “proper” transform of the grey point, with EOTF, tone, and sat mapping turned on, a different grey point needs to be used. For example, the native grey of Davinci WG is 344 or 86 IRE. With the transform remapping turned on, the grey point shifts to 100 IRE. So, which is the correct grey point?

I think a few things may be getting confused here, but the first is that I’m not quite sure what you mean by “709 card” — there’s really no such thing. An explicit, accurate, and fixed definition of middle gray is only possible in scene space. For a quick demonstration of this, apply LogC->709 transforms to a LogC gray card using RCM, ACES, and Arri’s K1S1 — each will plot that same input to a different output position. This relates to your discovery that attempting to map a display state image/value back into scene state isn’t a hard science with single solutions.

This is all to say that want to evaluate and work with mid gray independent of any display transform, and this would start by generating your initial mid gray value for evaluation in a suitable scene space. The math is fairly straightforward, but you can use my mid gray cheat sheet and/or Exposure Chart DCTL to make even quicker work of it. Hope this makes sense!

ahhh. I think I understand what you’re saying. 18% grey(what I called a 709 grey card) exists only in scene space. It doesn’t translate to a mathematically unique number in display space. Even tho’, that’s what I’ve been wanting to do to establish a baseline exposure in display space….in this case rec709.

Thanx, Cullen. Greatly appreciate your time.

Wow, thank you for all the discussion about my drp deliverable question.  I will say that in the past I’ve delivered a drp and when the output file they made came back to me for some other work, it looked very different, which is something I even warned them about.  So that is definitely a valid concern.  Also, I once had to create luts and deliver along with a drp since I used a 3rd party plug-in, not fun.

One thing that was not mentioned much in the discussion: if you do work for Amazon, Apple, Netflix, and a few other major studios, they do insist on “owning” all the session files used for their project. I think their fear is, “what if we need to come back in six months and the colorist got hit by a truck?” So there is a justifiable concern.

The post supervisors I’ve talked to tell me they get the actual Avid edit session (or the Premiere session), the full Pro Tools session, and the final color session as part of the entire deliverables package they assemble for the studio. Of course, they pay a premium price for this, particularly when you consider there could be 4-5-6 passes for different HDR versions, different aspect ratios, theatrical vs. broadcast/streaming, and so on. Even worse for 3D and large format theaters.

If I have to freelance for a specific company and use their facility, then they own the session at the end of the day. I accept that, because that’s the freelance world out there. In my own boutique room, I own the session and nobody gets it. When you go to a fine restaurant, you pay for the meal — not the recipe.

Everything is always subject to negotiation, and I won’t tell somebody “no” — I’ll just remind them that in our deal memo, we specify that we keep all session materials and that the client only gets the final renders. I’m open to offers, but my guess is for a feature, I’d want the equivalent of another 10-hour day for the file, just out of principle.