Using ACES

Different 3D software have different OCIO configurations, and the versions may also vary. Would using them directly cause inconsistent color conversions? Should I download the latest OCIO configuration file from the OpenColorIO official website and set it as a system environment variable “OCIO = Path/.ocio” in Windows to ensure that all software can use this OCIO configuration?


Between ACES 1.0.3, 1.2 and 1.3 nothing has changed in a way that would change your color. The only thing that is new in 1.3 alongside some new color spaces is the introduction of the Reference Gamut Compression. I don’t know if any 3D packages or renderers are already utilizing this. This only works in 1.3 which uses an OCIOv2 config. The main difference in the v2 config over v1 is that the transforms are analytical instead of LUT based so they are more precise. It shouldn’t affect your work too much though, maybe only in some extreme cases.

Workflow wise some software may have their own ‘simplified’ versions of the configs with only the transforms they think the user may need within their package. If you find this practical for your use case it is totally fine to use them. However having your own edited config (or just the full CG or Studio config) allows for more flexibility and synchronizes your color I/O throughout all your apps making it more streamlined and consistent.

Thank you for your reply. I am an independent worker and no one provides pre-compiled OCIO configuration files for me. In this case, using the software’s built-in OCIO configuration may be better. Even though they may have different versions, the ACES space should be consistent. However, I am concerned that repeated conversions between different versions of ACES configurations may cause issues, such as inconsistent results when converting from sRGB to ACEScg and then back to sRGB.

Is it possible that inconsistent color conversions are unavoidable? Even if I use a unified OCIO configuration file, should I not worry about this?

You don’t have to worry about inconsistencies, the math for conversions don’t suddenly change, they are based on the color space/transfer function. Maybe down to a few decimal places the numbers can be different with v2 configs over the LUT based v1 but that shouldn’t affect your output. If anything I’d try to stick with using either v1 or v2 based configs throughout your entire project instead of both mixed.