Trying to transform and .exr sequence from linear to Alexav3log using oiio tools

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shaun...@gmail.com

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Oct 2, 2018, 1:16:39 PM10/2/18
to OpenColorIO Users
New user here
anybody able to help me understand how i can map the the AlextoLog configuration from Nuke into a config file
that i can then use to transform colors ? Currently im doing 

as basic -i [source.exr] --iscolorspace linear --tocolorspace rec709 -o [targetname]
works fine but need this to be linear to AlexaLog from Nuke. 

not sure how to do that 
Any help would be great

need to eventually loop this over python but i want to understand it first

Michael Dolan

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Oct 2, 2018, 10:57:47 PM10/2/18
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With oiiotool you can use

--colorconfig /path/to/config.ocio

to specify a OCIO config. You could then point it to the "aces_1.0.3/config.ocio" that ships with Nuke, or download the "aces_1.0.3" dir from the OpenColorIO-Configs GitHub repo and point to the config in there.

Alternatively you can set your system "OCIO" environment variable to the config path prior to running your command, which is what OCIO uses by default. 

Then it's just a matter of giving oiiotool the correct color space names to use from that config, for example:

oiiotool --colorconfig  /path/to/aces_1.0.3/config.ocio -i [source.exr] --iscolorspace acescg --tocolorspace logc3ei800_alexawide -o [dest.dpx]

If you're using the same config as what you're using in Nuke, you can use the same color space names you have set in knobs (i.e. match the Read node "colorspace" knob value; with surrounding quotes if the name has spaces).

Hope that helps,
Mike


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Michael Dolan

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Oct 2, 2018, 11:08:12 PM10/2/18
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Actually, rereading your question you probably want the "nuke-default" OCIO config instead of the "aces_1.0.3" one. That also ships with Nuke and is on the OpenColorIO-Configs repo, so use it in the same way.
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