ACES and Arri LogC4 in After Effects

Hello everyone. Thank you again for all the work you’re doing with color. And thank you all for your previous answers to my questions here. My studio currently uses After Effects 2022 and Fnord’s OpenColorIO plugin vs 2.1.1 to do our film and television animation work.

The most recent ACES config set we could find with all the pieces prebuilt is version 1.2, which has worked for us for the last few years. However we now have several projects coming in that require us to be able to convert to Arri LogC4, which is not a part of the 1.2 collection.

As proof of concept, I was able to take a plate delivered to us in ACES-2065, convert to LogC4, apply the CDL and then apply the Rec709 LUT that was provided and got a match to a baked Rec709 quicktime in the non-commercial version of Nuke, but I had to use the studio-config-v1.0.0_aces-v1.3_ocio-v2.1.ocio setup to access LogC4. I am unable to get this version, which seems to be just a single file rather than a folder and collection of files, to work in After Effects.

I tried to see if the updated Nuke default OCIO configs would work by cheating ACES into LogC3 with aces 1.2 (as I’ve done in the past) and then using the Nuke defaults to go from LogC3 to LogC4, but the reds are bit more intense and the image is slightly brighter. I’m doing this in After Effects by using multiple OCIO effects with different configurations loaded in each. To be clear, it’s not way off, but it’s not a perfect match like it is in Nuke using the studio config.

There’s clearly something wrong with this cheat, so I’m reaching out for help to find a solution. Perhaps there is a way to load the newer ACES config into the AE OCIO plug-in as is? I get an error message saying “Color space ‘default’ not be found”.
Or there is a LUT-based version of ACES somewhere that includes LogC4 that I was unable to locate?
Or there is another path to jump from ACES to the Nuke default OCIO configs that we could use.

Any help with this would be greatly appreciated. Thanks.

I believe after effects now comes with ocio built in:

Additionally the fnord plugin should be compatible with an OCIOv2 config. You may just have to edit the config to get rid of the error message

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Hi Gregory,

OCIOv2.x configs only need a config file because most of the required data is already present in the implementation. On top of that the transfer functions and matrix conversions are defined inside the config file rather than being LUT based providing proper accuracy and removing the need for lots of dependencies.

There is a quirk in the fnord plugin that requires there to be a default colorspace role defined for OCIOv2 configs. This isn’t present in the ACES compiled configs but can be added very easily.
Open the config file in a text editor and in the Roles: section (very first block below the config info) add:
default: ACES2065-1
Save it and it should open correctly.

As @Derek mentioned OCIO is also available natively in AE in the latest versions but it still has a lot of quirks workflow wise. Currently in BETA they finally added OCIODisplay and OCIOLookTransform which are highly needed in an ACES workflow… There are other suboptimal aspects to the current implementation so I wouldn’t jump into it yet personally. Beta apps can be installed next to release though so on test machines you could have a stab at it.


The OCIO ACES config files are named so that in theory it is easy to see what they represent:

e.g. studio-config-v1.0.0_aces-v1.3_ocio-v2.1.ocio

if we break this up into tokens …

studio-config-v1.0.0 - This represents a version of the configuration, this will change when we add or remove colour spaces or change the roles, add new display outputs etc.

aces-v1.3 - This says which version of ACES release the configuration is based upon

ocio-v2.1.ocio - this says which minimum version of OCIO library is needed to use this file. As suggested above as we add new features to OCIO directly, we need fewer external LUTs to carry out the colour transformations. A good example of this in an ACES context it support for the gamut compressor was added to OCIO v2.1, so any config file using the gamut compressor needs OCIO v2.1 to work

Native “built-in” support for LogC4 happened in OCIO v2.2, so prior to that you would need a LogC4 → linear LUT and matrix transform from ARRI Wide gamut 4 to your config reference space (ACES 2065-1 for ACES config) for OCIO v2 you can use the file ARRI.Input.ARRI_LogC4_to_ACES2065-1.clf to represent this, or the config file studio-config-v1.0.0_aces-v1.3_ocio-v2.0.ocio shows how to do this directly in the configuration file in a OCIO v2.0.0 compatible way, the colourspace definition in this file can also be used with some edits in an OCIO v1 compatible configuration file, but you will need to bake out a LUT for the Log transform…



Thank you for this.

Adding this line causes it to work and placing the file into a folder and renaming it config.ocio allows it to be added to my list of default configs (this is important in a mixed OS environment so that it will be loaded regardless of the path).

I now have a perfect match between what I did in Nuke, the baked reference quicktime and what I can produce in AE.

If anyone knows how to / has access to the github, creating a version like this would be extremely helpful for others who need to work like I do. The fnord plugin is much easier to share with clients and smaller vendors, especially because they’re more likely to have older versions of AE that don’t have the built-in ACES settings.

Thanks again.

Thank you for this explanation. That makes a lot of sense. I’ll follow your links and research it further.