OCIO Color Management - ACES

This article is an overview of ACES implementations in different VFX software packages I use and will be constantly updated. At the bottom you'll also find further links and additional resources.


If you're looking for a detailed breakdown of the workflow I can highly recommend this article by Chris Brejon.


Software implementation


Nuke & Nuke Studio


Export Plates as EXR in ACES2065-1 (AP0) from Nuke Studio.

Work in ACEScg (AP1).

Export in original source color space if necessary.

In this instance I'm exporting the image in the ARRI LogC color space. I've also created a toolset you can use as a viewer input node for viewing ARRI footage as seen with their Rec709 LUT. The LUT was generated with the ARRI LUT Generator.

ACES_logCRec709_LUT
.rar
Download RAR • 225KB

Affinity Photo


Export plate from Nuke as ACES AP0 (ACES2065-1) or any other ACES color space (just write the according color space e.g. ACEScg in the filename for Affinity Photo to interpret it right).


Do your paint work in 32bit and export as EXR (same rule; color space depends on file naming).


Note: I've noticed that ACEScc files tend to be smaller due to the logarithmic compression without compromising image quality.





Photoshop


Export plate from Nuke as ACEScc

Install sRGB ACECcc ICC Profile for Photoshop

Enable Proof Setup in Photoshop and do your paint work.

Note: ACEScc is a log encoded file format, therefore offset should be used as an exposure control to check image in different exposures

Import Matte Painting back to Nuke as ACEScc

Davinci Resolve



To export ACES AP0 EXR files you have to disable the ODT in the project settings. (The image looks now the same as if you set your Nuke viewer to RAW)


Export LUTs

  1. Apply Grade

  2. Disable ODT

  3. Export LUT

Import LUT inside Nuke with the OCIOFileTransform Node and use working space as used in Davinci (ideally you write that information in the LUT filename e.g. shot010_lut_v01_ACEScct.cube).


Maya & Arnold


Go to Preferences Color Management Tab

  1. Enable Color Management

  2. Choose ACEScg as Rendering Space

  3. Choose ACES RRT as View Transform. The view transform is applied to Viewport 2.0, UV Editor and Render View. It is also applied to color pots in the Attribute Editor including solid colors, ramps etc. The View Transform should be the same tone map that is used in the comp application (e.g. Nuke).

  4. Leave "Apply Output Transform to Render" off, if you are rendering final images (everything that goes to comp and needs scene-linear values). If however you want to perform an output transform, keep in mind that Maya still applies the View Transform in the Render View. In the Arnold Render View Display settings switch the View Transform to raw (=off) to avoid looking at the image with double transforms.


Arnold render settings



Color Space is set to "Use Output Transform" by default. As long as you leave the "Apply Output Transform to Render" off in the preferences, you can keep the default. No output transform will be applied and this setting equals the option "raw", that is also available in the drop down menu. If however "Apply Output Transform to Render" is enabled in the preferences, setting Color Space to "Use Output Transform" will apply the transform specified in the preferences.


Additional info

  • if you want to use a custom OCIO config you can set it up via the OCIO config path

  • "Apply Output Transform to Playblast" should be turned on, so playblasts can be viewed on devices/software that do not apply appropriate view transform to scene-linear images

  • in the Color Management preferences you can also create rules, how image (e.g. texture) files will be read in. By default it will read tx, hdri, exr as raw and everything else as sRGB

  • Maya color management preferences


Houdini

  • Open the Houdini environment config file. You'll find it here:

Linux: ~/houdiniX.X/houdini.env

Mac: ~/Library/Preferences/houdini/X.X/houdini.env

Windows: %HOME%/houdiniX.X/houdini.env

  • Add the following at the bottom:

OCIO = " the path to the OCIO config file, like ...../ACES_1.0.3/config.ocio , with quotes "

More info: https://www.sidefx.com/docs/houdini/io/ocio.html

  • In the render view right click and enable Color Correction. Now you see options for the ACES ODT. You're now rendering your images in ACEScg.



Cinema 4D




Additional resources:

https://github.com/ampas

https://github.com/imageworks/OpenColorIO-Configs

https://cgrenderdna.blogspot.com/2019/06/updated-acescg-workflow.html

ARRI ACES Workflow

Video Tutorial about color grading in ACES and the theory of ACES

Autodesk ACES

Getting to know ACES by MixingLight.com

An Idiot’s Guide to ACES by toadstorm

ACES Central User Guides

OCIO ACES in VFX Pipeline - Falk Lude
.pd
Download PD • 11.22MB
cinematic_color_ves
.pdf
Download PDF • 6.00MB





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