OpenColorIO COP2 nodes for Houdini as Nuke counterparts

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OpenColorIO COP2 nodes for Houdini as Nuke counterparts
An unofficial HDK plugin to bring Nukes well known OCIO nodes to Houdinis compositing network.

What is OpenColorIO?
Please have a look at this official explanation. []

Where is it integrated?
In an increasing number of applications, amongst them are Nuke [], Mari [] or VRay3 [].

OpenColorIO COP2 nodes?
OCIO (OpenColorIO) is an open source library created by Sony Pictures Imageworks, that is ment to unify and centralize
the color management throughout an animation or VFX production. As an integral part of those pipelines, it makes sense for Houdini to support it.

Here [] is a little introduction video

And some images:
  • Tab Menu []

    OCIOCDLTransform: []
    Applies an ASC CDL (American Society of Cinematographers Color Decision List) grade based on the OpenColorIO Library

    OCIOColorspace: []
    Apply a color transformation based on a .ocio file. Ocio files are yaml based and describe the complete available colorenvironment. The color environment in turn usualy consists of a dozen Lut files which describe transformations to/from the reference color space to the target space.

    OCIOFileTransform: []
    Accepts a path to a specific color lut file and does a color transformation based on it.

    OCIOLogConvert: []
    Do a color transformation from Lin to Log, or the other way round, based on the Lin and Log roles of the given .ocio config file.


    Plugin Status
    Please note that the plugin is currently in alpha status. There are still bugs here and there [] but i guess it's best to release it now, so maybe it will get some true battle testing.
    Should you find bugs, please feel free to submit them on the github issue tracker [].
    Also please feel free to fork or clone the repo and build the plugin for your platform. I currently only supply precompiled binaries for H13 for windows, built with msvc11.
    (I want to supply Linux binaries as well, since i know about its importance in the Houdini community, as soon as i have a Linux build setup up and running).

    Git Repository []


    Download and additional information
    Additional information can be found on my website. []
    Download [] the precompiled binaries here (H13, Win, MSVC11)
    The download contains example images and scenes.

    I hope the plugin is of use to somebody :wink:
Edited by - Feb. 23, 2015 03:32:30
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Is there a way to use these nodes as the Mplay LUT?
823 posts
Joined: April 2008
It would be really nice to know the answer to the question above. []
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320 posts
Joined: Jan. 2015
You might be interested in this:

from H16 documentation (scroll down a bit): []

"Using OpenColorIO for display

OpenColorIO can be used for color correction by setting the environment variable OCIO to a valid OpenColorIO configuration file. The default colorspace can be set using the OCIO_ACTIVE_DISPLAYS and OCIO_ACTIVE_VIEWS environment variables. These environment variables are specific to the OpenColorIO library and are not Houdini environment variables, so they cannot be put in the houdini.env file.

When OpenColorIO is active, the gamma and LUT controls are replaced by Display and View menus. These define the output colorspace for the display. The colorspace within Houdini is linear, and the scene_linear role is used to specify the OpenColorIO linear colorspace.

MPlay can load both linear and non-linear files, such as OpenEXR (linear) and JPEG (sRGB). Renders from mantra are in linear space, and flipbooks from the viewport are either sRGB or linear, depending on the “Render Beauty Pass Only” option (linear when On, sRGB when off).

For sRGB files and sources, the source colorspace used for sRGB is defined by the Houdini environment variable HOUDINI_OCIO_SRGB_FILE_COLORSPACE. If this variable is not defined, the OpenColorIO config file is searched for a colorspace that matches srgb, either fully or partially.

This feature is still under development. The current functionality is unfinished and subject to change, and may have thin or no documentation. Please bear this in mind when using this tool."

and []


61 posts
Joined: May 2018
Awesome job! This is exactly what I was looking for.

Anyone had any luck getting this working with Houdini 17+?
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85 posts
Joined: July 2007
Create a VOP COP2 Filter node, dive in and build this:

Promote these parameters to a separate tab of this VOP container.
Go back to COP level, add a useful name (ie ACESburn) and drag it to the gallery, now you can use it anytime for colour space conversion. This is for ACES, but should work for other OCIO configs.
Edited by xilofoton - Sept. 13, 2019 18:39:17

Houdini_ACESburn_VOPCOP2.png (70.1 KB)
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