Houdini Color Management Discussion

Ideas
1

Hey everyone,
Changes in Settings for Houdini color management can be discussed there!

My proposal

Houdini Workfile Color Settings

  • Display: default display, it accepts Colon-separated list of displays, e.g ACES:P3, Read more Active Displays
  • View: default view, it accepts Colon-separated list of view names, e.g sRGB:DCDM Read more Active Views
  • Review Colorspace : Review output transform which exposes OCIO Colorspace parameter in opngl nodes, Read more Houdini OpenGL

you might also want to check: OpenColorIO support

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Unnecessary

Houdini Color Management Research

This is a research about color management in Houdini. Iā€™ve no idea why I included it in this post.

Render Space

Houdini uses scene_linear role as render space.
I donā€™t know if itā€™s possible to override that.

File rules

Iā€™m not sure about file rules for textures input transforms because Houdini seems to have some fixed built in file rules.

Houdini Color Management Research

This is a summary of what Houdini supports in regards to color managementā€¦

OCIO Config Path

Already implemented.

Achieved by setting OCIO before launching Houdini
OpenPype/openpype/hooks/pre_ocio_hook.py at 4f1638b3a7b8a3b2152010552073f28b62bd268b Ā· ynput/OpenPype Ā· GitHub

Render space

Houdini uses scene_linear role as render space
I donā€™t know if that can be overridden without modify ocio config file
OpenColorIO-Configs/aces_1.2/config.ocio at 0857366ee279bd0e091c0b4f593fc17bc9687cb1 Ā· colour-science/OpenColorIO-Configs Ā· GitHub

Display

Display list is the active_displays list in config file
default display hou.Color.ocio_defaultDisplay() is the first item in the active_displays list

OpenColorIO-Configs/aces_1.2/config.ocio at 0857366ee279bd0e091c0b4f593fc17bc9687cb1 Ā· colour-science/OpenColorIO-Configs Ā· GitHub

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Setting OCIO_ACTIVE_DISPLAYS before launching Houdini will override the active_displays list
windows example:

set OCIO_ACTIVE_DISPLAYS=ACES

View

View list is the active_views list in config file
default display hou.Color.ocio_defaultView() is the first item in the active_views list

OpenColorIO-Configs/aces_1.2/config.ocio at 0857366ee279bd0e091c0b4f593fc17bc9687cb1 Ā· colour-science/OpenColorIO-Configs Ā· GitHub

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Setting OCIO_ACTIVE_VIEWS before launching Houdini will override the active_views list
windows example:

set OCIO_ACTIVE_VIEWS=DCDM:sRGB

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Input Transform Guessing

for Background images and Textures.
Houdini is checking file names for token and sets color correction accordingly,
but without them Houdini will assume that
8-bit āž sRGB
more than 8-bit āž scene_linear

Unlike Background images, Textures have few explicit color space options

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ROP Output Transform

Different ROP nodes in Houdini with their color settings

  • OpenGL :support applying output transform, (Render Space āž scene_linear)
  • Arnold : it has an explicit parameter
  • Karma : it has an explicit parameter
  • Mantra : I didnā€™t find any options, I guess it uses scene_linear by default
  • Red Shift ROP : it has an explicit parameter
  • USD Render : I donā€™t know
  • V-Ray : it has an explicit parameter
  • RenderMan : I didnā€™t find any options

I donā€™t know if these parameters affect Render Space or they are just post render transformations.

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2

For reference, Hereā€™s the PR that adds this enhancement.

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