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A color manager is a connection between Arnold and an external color management library like OpenColorIO or synColor. Color managers hold information about the availability of different color spaces and also transform RGB colors to and from the rendering color space.

Built-in Color Manager

Arnold has a built-in color manager. It implements the open-source OpenColorIO (OCIO) color management system and uses an OCIO v2 config shipped with Arnold. The color manager is configured to leverage the industry standard ACES color encoding system, setting the rendering color space to ACEScg. If no color manager is linked to in options.color_manager, the built-in one will take over. The default OCIO color manager points at the default OCIO config.

The name of the default OCIO color manager node is called ai_default_color_manager_ocio.

OCIO Color Manager

Through the 'color_manager_ocio' node Arnold can access color spaces defined in an OCIO config file. The color spaces are grouped by the families defined in the config file.


A path to the OCIO config file to use, if this is empty OCIO will try to load the config file from the 'OCIO' environment variable.

sRGB color space (narrow)

If it exists in the OCIO config, this should be set to the name of the 'sRGB Gamma' color space. This is used internally for input and output color spaces in 'auto' mode. If set by the user, this color space is also used as a reference to detect the rendering color space gamut and white point.

Render color space (linear)

This is the default linear color space that Arnold will use as its rendering color space. Arnold's default color space is 'sRGB linear, ' but this can correspond to any linear color space if needed. If chromaticities for this linear color space can be guessed or are user-specified certain spectral effects will take them into account, but no other adaptations for albedos, transparencies, etc. are applied.


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