Am Donnerstag, 13. Oktober 2016, 12:53:12 CEST schrieb Seweryn Niemiec:
> Hi
> Colour transformations using 3D LUTs (Look Up Table) are popular in
> cinematography but no so in photography (probably one of the causes is a
> lack of support for it in software). I use them a lot and I usually drop
> using Darktable for those cases and switch to Natron, but this solution is
> far from perfect (I love Darktable for many reasons).
> LUT transformation have to applied in pipeline after basic exposure and
> colour correction and before some other luma and colour corrections.

Well, there are several places where a LUT can be applied. Once in the 
beginning, to get you recorded video data to a known state (kind of replaces 
input color profile), then there are final looks LUTs that are to be applied in 
the very end (to make the linear pixels look ok, adding a gamma curve and 
maybe some film emulation, so basically the final grading). And then there are 
intermediate ones like you ask for.

We discussed that a few times internally and while I would like to support 
that, there is the problem of WHERE to have such a module in the pipe. Or if 
we should add LUT support in a single new module plus the the input/output 
color profile modules? So many options ... If you have more insight I would 
like to hear about it.

> AFAIK, ready to use implementation of this transformation is provided by
> OpenColorIO library via LookTransform function. It is used in most
> compositing programs (like Natron, Fusion, Nuke) and reads all popular file
> formats (3dl, cube, csp...)

I wouldn't like to add that dependency as it's a rather big one and somewhat 
opposed to the ICC based workflow we use. But we don't need it anyway, I 
already have written some test code that reads cube files and applies them.

> A have created issue for this
> Was there in the past any discussion about such iop?


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