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 to simplify the transition to Arnold 5. If no color manager is linked to in options.color_manager, the built-in one will take over.
This built-in color manager only knows about two color spaces:
'sRGB'which corresponds to the sRGB colorspace with its corresponding gamma, and
'linear'which corresponds to a linear color space with the sRGB gamut and white point. This "sRGB linear" color space was the default rendering color space in Arnold 4.
OCIO Color Manager
Through the '
' 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. Select auto to use the default sRGB color space defined in the config file.
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 not other adaptations for albedos, transparencies, etc. are applied. Select auto to use the default render color space defined in the config file.