About Linear Compositing

[chun9]

Hello.

These days I'm studying about Linear compositing.

Not just the CG compositing, about RAW materials(Sony F65, F55, Arri, Red etc)

To Composite Raw materials, maybe I use the ACES workflow(space), right?

What I confused is... ACES proper to a working space?

In lejeune Cedric's Recording, Titled "ACES as connecting color space in Flame", mentioned that ACES is good for workflow but not proper as the working space and tools don't work what I expected.

I understood his explained, but another recording, Tilted "Comping sRGB source in ACES in Flame Batch", He shows ACES compositing method.

Then... What's correct or recommend way for Raw materials compositing? ACES can handle Raw materials(linear) compositing?

And After compositing, If I delivered to Color Grading Tools(Lustre or Davinci or Baselight), What format is good for this?

[slavi1492]

Actualy it doesn't matter how you gona work, the only thing that matters is the final result. What ACES gives you is that it's unifys different cameras. Lets say that you have footage shot with Alexa and in same conditions another footage shot with RED. In theory if you convert those two footages in ACES color space they have to look the same. So you can use ACES to unify all your footages from different cameras.

How do you gona work after that conversion is something of your choise.

In the end what you are delivering again depends on what you are asked for. If colorist asked for ACES footage you can easily convert your final result to ACES color space without any loses, if you work 16bit float.

As colorist I would never asked for ACES footage, because it's difficult to grade directly in ACES. Most of the time I asked for 10bit DPX linear or with 2.2 gamma.

In resume:

1. ACES unifys your different footages in one color space (if something is shot in same conditions, even if there are different cameras it should look the same).

2. How do you gona compose is something you have to find for your self (my only advise is to work floating point).

3. You are delivering what you are asked for (different studios, different workflows).

[IgorRidanovic]

Strictly speaking, compositing or any post production work on RAW images is not possible until they are debayered (turned to RGB). At the time RAW is converted to RGB some processing decisions are permanently recorded into the image. These processing choices can be based on the metadata instructions, or can be completely improvised.

ACES implementation in most if not all software packages is a work in progress, as ACES itself is evolving.

[cedriclejeune]

Hi, you can use ACES as a working space, but it usually works better as a connecting space. In the "sRGB sources" video I show how to bring content into ACES, but you don't have to comp in ACES. ACES is a linear encoding space, so when you get raw material it gets linearised in ACES. Then from ACES you can deliver either Print Density log encoded material (Cineon like DPX flies) or linear EXR files, depending on what the grading facility requires. Hope this helps. 

[chun9]

Thanks for your answers.

But I'm still unclear about working space. If I use ACES as a working space, The tools(like colour curve, Keyer etc) are performed correctly?

Compare to keyer result in ACES and Rec.709, ACES has more red color. Is a characteristics of ACES? or depend on a working space, tools perform differently? The source has 16fp.

What part do I miss?

And If I composite CG Linear sources & just one Raw(convert to ACES) source... What view is right for this? Linear or ACES v0.7 to current monitor?

[cedriclejeune · Accepted solution]

About the tools, it's you telling if it works for you or not, I'm not a big fan of how they behave. It's pretty easy to try, as you have seen, tools perform differently, then it's a matter of choice. If you comp Raw and CG you can choose ACES as a working space, or whatever you want, my favorite being Linear with P3 primaries. Choose your display settings accordingly.