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OCIO Color Management

Nuke uses OpenColorIO for color management. All of the colorspaces in Nuke, whether those shipped with the application or custom colorspaces, are defined in OCIO config files.

Depending on the OCIO config file that you are working with, there are a number of colorspace options and roles (aliases to colorspaces) that you can set in Nuke. There are also default options, which change depending on what file type you are working with. When the default option is selected, the colorspace that Nuke has set for it is listed in brackets.

Tip:  Use the options in Preferences > Project Defaults > Color Management to apply them to all new projects.

1.

The color management dropdown determines whether Nuke uses the LUTs read from the configuration specified or the Nuke native LUTs. Selecting OCIO makes the relevant OCIO LUTs available to the Read and Write nodes in scripts on a per project basis.

All OCIO configurations except nuke-default automatically switch this control to OCIO.

2.

Set the OpenColorIO Config you want to use for this project.

Nuke ships with a number of default configurations, but you can:

• use a custom OCIO config file by selecting custom from the OpenColorIO Config dropdown and then entering the file path, or

• add your own config to your .nuke file. See Adding OCIO Configurations for more information.

Changing the configuration updates the Default Color Transforms accordingly. If the selected configuration is invalid for certain transforms, a warning displays.

3.

The working space transform determines what colorspace files should be converted to (Read) and from (Write) - it's the colorspace used by Nuke under the hood.

Note:  In earlier releases of Nuke, this colorspace was hidden because linear was always chosen as the working space. You may find that some operations work better in colorspaces other than linear. For example, some transforms work better in the CLog colorspace.

4.

You can use Default Color Transforms dropdown menus to override how clips in the Viewer, thumbnails, and so on are converted to and from the working space.

When the Nuke is selected, Reads and Writes work the same as in previous versions of Nuke, with no integrated OCIO transforms. When OCIO is selected:

• Reads and Writes use OCIO transforms, with no Nuke built-in LUTs applied to the image.

• Read and Write colorspace controls are populated with the list of colorspaces defined in your currently selected OCIO config.

• The default LUT settings dropdowns are also populated with the list of colorspaces or display transforms defined in your OCIO config. The default value for each menu match the defaults in a Nuke Studio project with the same config. These defaults can be overridden using Python callbacks. See the following path for the default implementation that ships with Nuke:

<install_dir>/plugins/nuke/colorspaces.py

• The working space dropdown allows you to change the colorspace that Nuke uses internally for its image processing. This automatically sets the in colorspace of Write nodes and Viewer Processes, and the out colorspace for Read nodes. This defaults to the scene linear role defined in your OCIO config.

• Nuke Studio-created comps no longer contain automatically injected OCIOColorspace nodes. Instead, OCIO Color Management is automatically set in the comp’s Project Settings, and the correct OCIO colorspace is set directly into the Read and Write nodes.

Adding OCIO Configurations

You can add your own OCIO configurations to Nuke as they become available, such as new versions of ACES. You can also add legacy configs for backward compatibility.

1.

Navigate to the location of your .nuke file as shown by platform. You may have to create a .nuke folder if it doesn't exist.

• Linux: /users/login name/.nuke

• Mac: /Users/login name/.nuke

• Windows: ~\.nuke

Note:  On Windows, the .nuke folder can be found under the directory pointed to by the HOME environment variable. If this variable is not set (which is common), the .nuke directory is under the folder specified by the USERPROFILE environment variable - which is generally of the form drive letter:\Documents and Settings\login name\ or drive letter:\Users\login name\

To find out if the HOME and USERPROFILE environment variables are set and where they are pointing at, enter %HOME% or %USERPROFILE% into the address bar in Windows Explorer. If the environment variable is set, the folder it’s pointing at is opened.

2.

Recreate the following structure within your .nuke folder:

~/plugins/OCIOConfigs/configs/<config name>

3.

Copy the contents of the config into the config name named folder. There should be a luts folder and .ocio file at the bare minimum.

4.

If Nuke is already running, relaunch the application to apply the change.

5.

You can now select your configuration from the Project Settings > Color > OCIO Config dropdown.