Re: reversable, but not 1D color transforms in config.ocio


Troy Sobotka <troy.s...@...>
 



On Thu, Feb 2, 2017 at 6:55 PM Andrew Wood <andre...@...> wrote:
Can you expand on that?    Looking into CTL now, does look like I could define L*a*b* there, but how would that tie in to a config.ocio?  I haven't used it before, got some reading to do

Tacking onto Sean's comments, roughly:
  • Use ociolutimage --generate --maxwidth 4225 --cubesize 65 --output all-in-one.exr to generate an all-in-one RGB EXR.
  • Roll that through your L*a*b* CTL functions via ctlrender. Generate two variants, one for to_reference and one for the from_reference, which would be the to L*a*b* and from L*a*b* respectively, assuming you want to do some work on the image in L*a*b* briefly
  • Use ociolutimage --extract --input ctl-rendered.exr --cubesize 65 --maxwidth 4225 --output foobar.spi3d for each of the to and froms.
  • Use the transform sparingly when you need to blur the first channel or whatever in your node chain, and get back out. Make sure you use proper shapers on the head and tail to shape and unshape accordingly to optimise your 3D LUTs.
With respect,
TJS

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