Hello everyone, I’m an assistant colorist and in process of learning ACES. We were trying ACES VFX workflow for a Resolve Color Managed project and created a test render following the guidelines of creating ACES Linear (AP0). Rendered ACES image was compared to the original raw footage by applying the grade and there was a slight saturation boost for the ACES Linear (AP0) EXR compared to the orginal file. Grade was bypassed and checked again (now in the vectorscope only) and still a small saturation difference. The AP0 Linear was tested in ACEScct in Davinci Resolve and in Filmlight’s T-Log/ E-Gamut 2 in Baselight Look, but in both cases the AP0 Linear EXR matched exactly with camera raw footage. We tried color managing with nodes by bypassing the color management for the individual clip, and couldn’t solve the problem.
I have attached two screen grabs showing the difference in saturation in the vectorscope. First is the ACES 2065-1 EXR file and second is the Camera Raw file.
To notice the difference easily look between the yellow vector and skin tone line in the scope, the saturation in the camera raw(2nd image) appears trimmed off at the left edge compared to ACES EXR (1st image).
Is this a color management mistake and could it be solved by manually managing with nodes or is it a common issue?
Not sure from vectorscope if your image would have values affected by the Reference Gamut Compression, but do a quick check to make sure that the RGC is being applied (or not applied) consistently. This is usually a checkbox option wherever “Input” settings are being configured - e.g. in an ACES Transform node or in the Color Management Settings Menu under the Input Transform dropdown.
If that’s not it, then could you either edit your post or reply with an attempt to more clearly just describe your steps for each as a “block diagram”?
e.g.
Cam Orig → ACES Transform Node with Input Transform → Grade → scopes image 1
vs
output of above rendered out to AP0 → ingest as AP0 → ACES Transform Node with No Input Transform → scope image 2
(or something like that?) I’m finding myself a bit confused what the two things your’re comparing, and which is which.
I have attached two screen grabs showing the difference in saturation in the vectorscope. First is the Camera Original file and second is ACES 2065-1 EXR
1st image → Camera Original → Original Saturation
2nd image → ACES 2065-1 → Saturation Changed in Resolve Color Management
To notice the difference easily look between the yellow vector and skin tone line in the scope. The saturation in ACES 2065-1 is more compared to the Camera Original.
Now I will try to demonstrate how I got the ACES 2065-1 image and how it was used in RCM using screengrabs, as I felt it would be easily understandable compared to block diagram.
Now, the color management for the original project, resolve detected the input transform automatically with the metadata with color primaries → ACES (AP0) and gamma → Linear.
Also uploading the footage I have used for the test along with a single EXR file (the first frame of the raw footage is what is shown in the Vectorscope).
For your braw to match the ACES EXR in Resolve color managed, simply uncheck that gamut compression)
…If you need that braw gamut compression to be baked into the ACES AP0/Lin EXRs, you would probably need to work non color managed and do it all node-based.
Wow! Thank you for figuring it out. I hope the solution is common for Sony too, I used Blackmagic Raw since it’s raw sample files from their website. Our original file is from Sony Venice. Looks like it’s the same problem there too. Will update it here as I try it.
In Sony camera raw section in resolve couldn’t find the gamut compression option, but looks like it’s happening internally. If there’s an option to turn off Gamut Compression please update. Ideally baking in the gamut compression to the ACES 2065-1 EXR works best for us. Just for the clarity with what I’m getting, uploading the Sony Camera Orginal and First frame of the EXR along with the vectorscopes for both.
Do you want to work in ACES or in non color managed? And do you want the X-OCN to match the EXR or vice versa?
…That gamut compression is unique to braw.
One thing you’re probably butting against is:
ACES color managed will debayer X-OCN using S-Gamut3/Linear with Venice primaries.
Non color managed will debayer with non-Venice primaries.
Venice primaries are only enabled/available in ACES. It’s been painful. There are ways with multiple CST nodes to make one match the other, but it’s a real headache.
We have started the project already with Davinci YRGB Color Management and wants our ACES EXR to match with the X-OCN. Since the colorist does the grade first with X-OCN and applies that grade to EXR after VFX is finished. Along with this I want to learn how it’s done using multiple CST nodes, the one you mentioned. Also can you mention are there any other camera formats having this problem?
Not the non-Venice/Venice mismatch between the Output of node 1 and Input of node 2.
Sony Venice (1 and 2), and I think Burano. Basically anything X-OCN is the only format which this issue. …Well, that and potentially ARRIRAW LogC3 when not shot at 800 EI, but let’s table that can of worms for another day
(Feel free to toggle on gamut compression on node 2 if you want it/need it)
Trying this first thing tomorrow. Also is ACES 1.3 the correct version for EXR conversion? I used ACES ver 2.0 (VFX team is using both After Effects and Fusion).
