Hello,
Apologies if this is a poor place for this post as it focuses on questions for a linear-sRGB color management workflow (for VFX) instead of ACES, but it is based around OCIO.
In the case of working with a linear-srgb color management workflow with OCIO 2, how should one navigate it? OCIO 1 released the spi-vfx, spi-ani, and nuke-default (OpenColorIO-Configs/config.ocio at master · colour-science/OpenColorIO-Configs · GitHub) which from what I can tell are based around linear-srgb CMWs. I also found the filmic blender config, which is also built on OCIO 1. Because of the backwards compatibility I know I can use any of these configs with OCIO 2, but I don’t know if they are the right choice.
The only prebuilt configs for OCIO 2 that I have found are the ones from Releases · AcademySoftwareFoundation/OpenColorIO-Config-ACES · GitHub, which focus around ACES, and the modified ones that ship with software like Maya 2023. In the case of the cg-config-v1.0.0_aces-v1.3_ocio-v2.0 , it does contain a linear sRGB profile with Linear Rec.709 (sRGB) , and then of course the sRGB - Texture colorspace. However, there is no sRGB gamut space with a log gamma to be used in the role of compositing_log or color_timing . Additionally, when loading this config into Maya and setting Linear Rec.709 (sRGB) to my working/rendering space, I get an error message from V-Ray saying “Unsupported rendering color space linear rec.709 (srgb)”.
The OCIO 2 config that ships with Maya 2023 doesn’t have this issue with V-Ray with their scene-linear Rec.709-sRGB space used as the rendering space, and it does have non-ACES log colorspaces (Although only the Log Film Scan ADX10 space works when I use the Maya config in a software besides Maya). However, when it comes to tone-mapping/applying a view transform, I initially thought untonemapped was correct but after learning some more I’ve heard that in linear-srgb tonemapping is for sure correct so that when turning down light intensities your scene doesn’t “lose energy” (“1D lut example” section from Chapter 1: Color Management - Chris Brejon). With this config, the views that seem to be meant for final images are ACES 1.0 SDR Video and one meant to reproduce the look of Unity’s tonemapping (Help). In a linear-srgb workflow it doesn’t really make sense to me to use a view transform intended for ACES, and the tonemap from Unity seems like an random arbitrary choice to make for tonemapping.
Overall though, it seems difficult to use the OCIO 2 configs that I’ve mentioned with a linear-sRGB workflow. I have seen good things with the Filmic Blender config, but the fact that it is an OCIO 1.0 config throws me off slightly. Even though there is backwards compatibility, I feel like I should be trying to use a current workflow, but let me know if that worry is unfounded.
I’m wondering if a good solution is to author my own OCIO 2.0 linear-sRGB config, but I don’t really know how I’d navigate doing that in terms of getting the correct transforms. However, I think all that I would need in terms of colorspaces is linear-sRGB, sRGB - Texture, Output - sRGB (inverse view transform), some sort of log colorspace for the compositing_log and color_timing roles, and a view transform with tonemapping. I would also be worried about getting error messages in V-Ray with my linear-sRGB rendering space like I did when I tried to use it as the rendering space from the cg-config-v1.0.0_aces-v1.3_ocio-v2.0 .
What advice do you have for navigating using a linear-sRGB color management workflow with OCIO 2?