Resolve difference between ACES/NCM Colortransform Node

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So, after some testing I figured out that resolve in ACES mode applies the Color Space transform differently to non color managed mode.

Afaik the processing pipeline when no IDT or ODT are checked in resolve does the following->

INPUT- AP0->CC(T) --> Grading Tree --> CC(T) —> AP0 --> OUT

LUTs get applied in a selectable space, either CC(T) or AP0 , but OFX seems like it gets fed CC(T) data, but not really? I dont really know whats happening here as the results are different, they are also different between CCT or CC modes.

When I use a LUT the results are the same between aces and NCM , in my case I went with the LIN->logC Lut/Tranform.

It would be expected that is does. From what I understand you are using Color Space Transform to manage an asset in AP0 Linear?

Have you ever used the Aces Color Transform instead of the “regular” worklfow? I’ve completely dropped using the standard ACES workflow with Resolve.

Cheers

yea I tend to also not use the aces mode at all and just do everything with nodes as I dont like things not being transparent. this is one of those reasons…

aces transform is sort useless as it only goes one way for man operations.

It shouldnt touch stuff at all when there is no idt or odt, colrospace transform is just touching gamma,

In this case I am just troubleshooting something as we couldnt match a nuke ocio stack in resolve in aces mode but have no issues in NCM mode, which sounded weird to me, wven though the sources are really lin/709 with custom tonemapping luts so not aces , I should be able to replicate it even in Aces mode if I reverse everything aces mode does under the hood.

But yea very intransparent .

I found that applying LUTs in “regular” ACES mode in Resolve does not yield good results. There’s somehting in the way it’s managing the LUTs that is “not correct”. With the OFX it’s much more straight forward and way more “Nuke like”.

SO you have 709 tonemapped images that you are pre-applying a LIN to LOGc LUT? I’m not sure I’m totally understanding what you’re trying to do.

Thanks

hmm I had no issues with luts, I just select apply in Ap0 and it does what I would expect.

So the long story is, Full CG production, everything is rendered in Linear with 709 primaries.
We use a setup of colortransforms and Luts for tonemapping those into display space (all this from before the aces days) .

Its just a lin-> LogC Gamma Only transform + custom LogC->sRGB Gamma only 1D LUT .

So basically nothing is changing the primaries or whitepoint they just stay “as rendered” so 709/sRGB and D65 Whitpoint. only doing tonemapping. Similar to how tonemapping option in lets say Octane or Vray or Unreal would do it.

Now I was trying basically for Research to do the same transform chain in Resolve ACES , mostly to understand the “under the hood” stuff of resolve Aces, as Ive always found it “weird” anytime I tried it and just resorted to doing everything with nodes… seems like I will just stay in nodes world :smiley:

Ah ok! Yes you’d need to stay with nodes. Or use DCTLs to revert from one gamma to another inside ACES. But, NODES are much clearer for this (as you now know).

One big problem I have with the “regular” ACES. mode in Resolve is how all things created in edit (transitions, titles etc…) just slams into ACES unmanaged (for example). With nodes I can bypass these problems.