Nuke14 Aces2065 logc4wide to rec509 issue

Discussions - Using ACES VFX
1

Hello, I don’t know if this is the place to post a topic to ask for a hand (thank you for your patience).

I have to set up a nuke workflow with the specs of a lab but I can’t find my way around.

Here is the production context for VFX:

source: Arri Alexa LogC4 ARRI Wide Gamut 4 (the lab indicates to provide in ACES Linear AP0 2065-1, but the meta data clearly indicates that the rush exr is in LogC4 ARRI Wide Gamut 4)

and the lab notes this to work;
ARRI Alexa, Colour order of operations for Rec.709 Quicktimes:

ACES 2065-1 AP0 => Nuke: OCIO to LogC4 ARRI Wide Gamut 4 => CDL Grade > Rec709
Show LUT (full range) Scale to Rec709 legal video range (16-235) 2.4Gamma

(this whole part is a mess ! I precise i’m a junior)

I tested by putting my project settings in aces2065, in aces cct or acescg but impossible to make an export that looks like the lab reference video.

I feel like I’m at a dead end, so someone can guide me?

Thanks in advance.

Friendly

2

Hi,

I am not sure if I understand the workflow completely correct, but it sounds to me that this could be the order of operations.

Alexa35
Alexa351920×1080 142 KB

Best
Daniel

1 Like
3

Hello Daniel, thanks for your help.
I will test asap today!
Bests regards,
Papy

4

the second DOT node should be labeled as Read in as ACES 2065-1!

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5

I think I guessed, but thanks for clarifying anyway !
Sometimes we forget the obvious things :wink:

I will test at the end of the day; thanks again

6

Hello @TooDee ,
I switched AriLogC4 to Linear Arri Wide Gamut 4 and now i’m close to match the result; it’s much better but It seems there is a little shift somewhere (gamma and color) to match the lab reference.

Thanks for your help again !

7

The plates you receiving are in ACES2065-1 according to the spec so you need to convert these to LogCV4 apply the provided cdl and then apply the supplied display lut using the file transform nodes. This is a pretty standard ACES hybrid workflow.

Your config needs to be an ACES OCIO config so exrs are treated as ACES2065-1 currently I see the read node set as Alexa Wide Gamut v4 this is not correct they are giving you ACES 2065-1 encoded files

The read node should be set to ACES 2065-1 which will put the colour into ACES cg working colourspace of Nuke. Use a colorspace node to convert from ACEScg to Alexa LogCV4 then apply the cdl and the provided display lut. It should match the reference then.

8

Hello, thank you for your valuable information; I was finally able to find the solution that corresponds to what you describe!

it was necessary to put the project in Acescg; the read in Aces2065 add an ocio look transform from Acescg to Arri Logc4; then cdl and lut.
So we have a perfect match with the ref edit of the lab!!

Thank you everyone :wink: