Hello everyone, I’m new here. I also posted this on WeSuckLess, so I’ll just copy-paste the text. Please let me know if doing something like that is frowned upon, but I figured since this is a Resolve/Fusion and ACES issue, why not ask both communities?
I’ve come across an inconsistency in how I would expect the CSTs to work in both Resolve and Fusion but I’m guessing I’m missing some information. My hope is that someone can help me understand what’s going on and if my workaround is somehow affecting quality in some way.
For context: I do independent freelance VFX work for independent productions, so anything close to a color managed pipeline for the whole project is too much to ask for BUT I want to stablish my own roundtrip workflow to be able to deliver back files that’ll cause no issues when color grading etc. I wanna use ACES for this, partly to teach myself and get used to the ecosystem. I want to make my VFX Pushes and Pulls in EXR.
So, here’s the issue: applying a CST inside Resolve from source to ACES (AP1 cct), then ACES to my monitoring display gives me one, correct, reference look. From Resolve I export EXRs on ACES AP0 Linear and bring them into Fusion. If I use a CST node to take them from AP0 Lin to my monitoring display, it looks as if it had a different gamma, HOWEVER if in Fusion I first use a CST node to do AP0 Lin to AP1 cct, and then another from AP1 cct to my display, it looks exactly like the reference. What am I doing wrong to be needing two transforms, or what do I not understand about ACES?
Full procedure:
Inside Resolve I’m in a non-managed timeline, I bring in the camera originals and manually add a first CST node to bring them into ACES AP1 ACEScct, from there I add another CST node, this one to the whole timeline, to go from AP1 cct into Rec.709 Gamma 2.4, because that’s the display I’m monitoring in and what my final output will be. Doing this process gives me what I’ll call “Look1”, which looks correct (in color and gamma) to me and we’ll define as the baseline. My VFX monitoring inside Fusion should match this Look1, because I’m literally using the same computer and displays, and that’s the whole point of ACES.
That was just to have the reference and know the roundtrip worked properlly. To export the EXRs I use a CST node to bring the camera originals from whichever gamut and gamma they are in, into ACES AP0 Linear. No other nodes are applied. On the delivery page I make sure it tags them as AP0 Lin, and export EXR RGB half (piz).
As stated above, inside Fusion using a single CST AP0 Lin to Rec.709 2.4 node would give a different look to the baseline “Look1” I’m seeing in Resolve, so I gotta do a two step CST process: AP0 Lin to AP1 cct, AP1 cct to Rec.709 2.4, and use this node as my viewing node. To roundtrip I then do another two CSTs: 709 2.4 to AP1 cct, AP1 cct to AP0 Lin, and then to a saver node, Open EXR, with output color and gamma set to Keep.
Back in Resolve, doing a CST from AP0 Lin to 709 2.4 gives me the correct “Look1” that’s exactly as the baseline reference stablished earlier. Pixel peeping the waveform and vectorscope shows no changes between the reference and the roundtrip’d, once they’re both in 709 2.4, so I’m assuming it worked, but I’m very curious as to what I might be doing wrong that Fusion needs a two-step CST transform to look exactly like Resolve, when back in Resolve the same AP0 Lin file can look exactly like the reference with a single CST.
I hope I’m being clear, both on my question and my process. Thank you to anyone who might know what’s going on.