1.4.1. Blender 3.2 alpha & OCIO v2-beta

Setup Blender 3.20 (alpha) to work with OpenColorIO-Config-ACES 0.2.0 (OCIO V2-Pre-Release)

Just some days ago I installed macOS Monterey 12.3 and now I got Metal support for GPU rendering on my 2020 iMac27″ with AMD Radeon Pro 5700 XT 16 GB graphics. A quick benchmark rendering of the “Junk Shop” scene nearly doubled my render speed from 55s CPU to 29s GPU. Finally!

And now I found a tweet about the first pre-release of a OCIO V2 (OpenColorIO-Config-ACES 0.2.0) config. The beta config can be found on GitHub.

I wanted to test the new config in Blender in the same way I did in the past with the OCIO V1 configs. The instructions can be found on the previous page and also here in a shortened version:

MAC “Automator” script

export OCIO=/Users/daniel/MEDIA/ACES/OpenColorIO-Config-ACES-0.2.0/config-aces-cg.ocio

cd /Applications/Blender/blender.app/Contents/MacOS/

./blender

Blender did not start with the new config because of a version conflict of OCIO V2 that reads:

OpenColorIO Error: This .ocio config ‘/Users/daniel/MEDIA/ACES/OpenColorIO-Config-ACES-0.2.0/config-aces-cg.ocio’ is version 2.1. This version of the OpenColorIO library (2.0.0) is not able to load that config version.
The minor version 1 is not supported for major version 2. Maximum minor version is 0.

Just for fun I changed the first line in the config “config-aces-cg.ocio” to: ocio_profile_version: 2.0 instead of 2.1.

Update:
I received an answer from Thomas Mansencal on ACESCentral.com. It is okay to change the version number in the OCIO.config. In this case it has no negative effect.

For now this did the trick and Blender starts with the new config and seems to run fine. I re-rendered the old scene I used for my Blender&ACES 1.2 setup guide and compared the two ocio-configs:

Blender 3.2 Alpha with OCIO v2 config – viewer set to Rec.709
Blender 3.20 Alpha with OCIO v2-ACES 0.2.0 config – viewer set to Rec709.

The render results are identical.

macOS 12.3 – 27″ iMac (Intel & AMD) bug

As I was setting up this test on my 2020 27″ iMac, I ran into display bug. By default the Device Display is set to “sRGB”. I rendered the first test images, and only the cyan sphere turned partly magenta somehow.

Blender 3.2 Alpha running a OCIO v2 pre-release config.
Blender 3.20 Alpha with OCIO v2-ACES 0.2.0 config – viewer set to sRGB.
Blender 3.20 Alpha with OCIO v1-ACES 1.2 config – viewer set to sRGB.

With the OCIO v1 config this never happened before. This only seems to happen when the Blender “Display Device” is set to sRGB! After I tested around a bit, I found out that changing the Display Device to Rec.1886 / Rec.709 Video does the trick. The image looks fine again.

Further testing and after posting a bug report for Blender, I realized that I cannot replicate the issue on a M1-Max MBP. So maybe it’s not even a Blender but a macOS issue.

https://developer.blender.org/T96590

I posted this “issue” also on ACESCentral in the following thread:

OpenColorIO 2 Configs for ACES


Furthermore I found out that the PNG writer in Blender from the Render View writes out a broken image. The JPG writer works fine.

I will continue testing and looking out for other problems and issues. For now I am happy to see a modern and small config running OCIO v2 that makes the life in Blender a bit easier when it comes to selecting the right colorspaces.

OpenColorIO-Config-ACES 0.2.0 config with a limited set of colorspaces.