OCIO 2.3 Release


OpenColorIO 2.3 was delivered in August 2023 and is in the VFX Reference Platform for calendar year 2024.

New Feature Guide

New config editor GUI app ocioview

There is a new GUI app for inspecting and editing OCIO configs called ocioview. As of the 2.3.0 release, ocioview is currently in an alpha release (please see the README in the apps/ocioview directory for details). Documentation and tutorials will be forthcoming and we are looking for contributors to help with this and other tasks.

Built-in Configs

An updated set of built-in CG and Studio configs is included in the 2.3 release. These include the updates from the OCIO Configs Working Group over the past year. The updates include:

  • Addition of Apple’s Display P3 as both a texture space and a display

  • A texture category to allow filtering of color spaces typically used for textures

  • More appropriate color space assignments for the matte_paint and texture_paint roles

Additional updates for the Studio config include:

  • Support for CanonLog2 CinemaGamut color space (in addition to the existing CanonLog3)

  • Addition of ACES Transform IDs to better support the ACES Metadata Format (AMF)

For Users

The following URI strings may be provided anywhere you would normally provide a file path to a config (e.g. as the OCIO environment variable):

To use the updated OCIO CG Config for ACES, use this string for the config path::


To use the updated OCIO Studio Config for ACES, use this string for the config path::


This string will give you the current default config, which is the latest ACES CG Config::


Because there are now several built-in configs, there is now a short-cut to referring to the latest versions:

This string will always give you the latest CG config::


This string will always give you the latest Studio config::


For Developers

As the built-in config collection evolves, special names such as ocio://default and ocio://studio-config-latest will point to newer versions of those configs. Therefore, it is recommended that application developers not save those strings and instead save the string that refers to the current version of that config. That way, it’s guaranteed that there will be no change of behavior in the future. For example, as of OCIO 2.3, ocio://default should be saved as ocio://cg-config-v2.1.0_aces-v1.3_ocio-v2.3.

The method for doing this is to use the new ResolveConfigPath function. For example: ResolveConfigPath("ocio://default")

And if you intend to present a list of built-in configs to users, be sure to filter the list of configs returned by the BuiltinConfigRegistry and only show the ones where isBuiltinConfigRecommended is True so that you are only presenting the most recent versions of each of the built-in configs.

Improved Lut1D and Lut3D performance via AVX SIMD intrinsics

In some cases, this gives more than a 2x speed-up in CPU Renderer performance.

For Developers

The library now contains multiple Lut1D and Lut3D evaluation routines and the appropriate one is selected at runtime based on which SIMD instruction set is supported by the chip. Please let us know if you encounter any issues as you test on various flavors of x86 hardware.

Improved support for macOS ARM chips

For Developers

SSE SIMD intrinsics are now converted to the equivalent Neon intrinsics when building for the arm64 platform.

In addition, the build process for generating macOS Universal Binaries has been improved.

OCIO command-line tools are now available via PyPI

For Users

Doing a pip install opencolorio now gives you the command-line tools such as ociocheck, ociochecklut, and ocioconvert.

Enhanced methods to find an equivalent color space between configs

In OCIO 2.2, several methods were introduced that used heuristics to identify a color space in a user’s config that matches one of the known color spaces in the default built-in config. In OCIO 2.3, these methods were improved and extended as follows:

  • IdentifyBuiltinColorSpace Searches a user config to find the name of an equivalent color space to a color space in one of the built-in configs. For example, “What is the name in this config for the sRGB - Texture color space from the default built-in config?”

  • IdentifyInterchangeSpace Identifies the pair of color space names to be used as the interchange space to allow conversion between color spaces in a user config and one of the built-in configs. This is now the fundamental function that contains the heuristics for trying to identify known color spaces and is used by IdentifyBuiltinColorSpace and in the GetProcessorFrom/ToBuiltinColorSpace methods.

This improves upon and extends upon PR #1710. One piece of feedback on that PR is that it would be helpful to be able to use the heuristics to extract the names of the interchange color spaces rather than a Processor. This gives the application more flexibility in how that information is persisted and may reduce the number of times that any heuristics (that search through a config’s color spaces) need to be run.

Finally, an issue was fixed in GetProcessorFromConfigs so that the returned Processor is a no-op if either of the color spaces in the two configs is a data space.

Note that if the official interchange role(s) are present (as is required in configs with ocio_profile_version 2.2 or higher), the above methods simply use those rather than relying on any heuristics.

Breaking API Change

For Developers

For developers that have customized their GPU Renderer by overriding the GpuShaderCreator class, there is a minor breaking change in the API. The addTexture and getTexture virtual methods now take a TextureDimensions parameter. This was necessary to give client apps full control over whether 1D or 2D textures are used for Lut1D ops. Please see PR #1762 for an example of how to update your implementation of these modified virtual methods.

API Enhancements

For Developers

You may find the following additions to the OCIO API useful:

  • There is now a clearProcessorCache method to clear the Processor, CPUProcessor, and GPUProcessor contents from the cache present in a Config instance. This is useful if a LUT file on disk has changed since the Config instance was created.

  • The setAllowTexture1D method on the GpuShaderCreator/GpuShaderDesc class allows your GPU Renderer implementation to always use 2D textures rather than 1D textures for Lut1D ops.

  • The Config class now has GetProcessorFromConfigs variants that allow converting from a source color space in one config to a display/view in another config.

  • The Config class now has an isInactiveColorSpace method and getRoleColorSpace method.

  • The CPUProcessor now has the isDynamic and hasDynamic methods that were present on the Processor class.

  • The ResolveConfigPath function converts one of the built-in config short-cut strings into the unambiguous full URI for the current config.

  • The new IdentifyBuiltinColorSpace and IdentifyInterchangeSpace methods are described above.

New Built-in Transforms

For Config Authors

In config files with ocio_profile_version set to 2.3 or higher, config authors may take advantage of the following new transform:

  • DISPLAY - CIE-XYZ-D65_to_DisplayP3 To implement a display for the Apple Display P3 color space

Release Notes

For more detail, please see the GitHub release pages:

OCIO 2.3.0