Config - Add cdl per shot

[sbaykal]

Hello,

I am trying to create a view in the OCIO config that matches to the grading of the DoP.

I managed to match the colo in Nuke from the exr with a mov provided by the lab. Here is how I did it in Nuke :

If you compare the outputs of the two last node in Nuke the colors matches.

But I do not know how to reproduce these steps in the OCIO config. I tried to follow this answer but the image doesn’t match and I don’t know what to try.

ACEScct LUT to ACEScg

So here is a modified version of the Redshift config to use with a LUT. What you need to add yourself is a folder next to the config named luts and place your ACEScct based LUT there with the name showLUT.cube or rename it to whatever you want it to be and also change that name inside the modified config file. The lines that I changed/added in the config are: search_path: "luts" to add the folder luts to the search locations for using external files inside the ocio config. Under shared view…

Thank you

[shebbe (Shebanjah Klaasen)]

Hey @sbaykal ,
Sorry to hear you haven’t been able to implement it into an OCIO config. I’m not a total expert when it comes to customizing OCIO but I think CDL files should also be supported. What is the current code of your added look?

[sbaykal]

Hey @shebbe thank you for help, here what I added in my config.

in shared_view :

  - !<View> { name: ShotGrading, view_transform: ACES 1.0 - SDR Video, display_colorspace: <USE_DISPLAY_NAME>, look: shotgrading}

in display :

  Rec.1886 Rec.709 - Display:
    - !<View> { name: Raw, colorspace: Raw }
    - !<Views> [ACES 1.0 - SDR Video, ACES 1.0 - SDR Video (D60 sim on D65), Un-tone-mapped, ShotGrading]

in looks :

  - !<Look>
    name: shotgrading
    process_space: acescct_ap1
    transform:
      !<FileTransform> {
        src: path/file.cc,  # this is a pseudo path
        interpolation: linear,
      }

I get no error but it’s not matching

[shebbe (Shebanjah Klaasen)]

Is it matching that of only loading the .cc file with CDLTransform in Nuke and bypassing the FileTransform .cube file? Since your look is not including both that seems to be expected that they don’t match. You would have to make a look that defines both files. To use multiple operations it needs to be a group transform. Something like this.

 - !<Look>
    name: shotgrading
    process_space: ACEScct
    transform: !<GroupTransform>
        children:
            - !<FileTransform> {src: cdl.cc}
            - !<FileTransform> {src: showlut.cube, interpolation: tetrahedral}

[sbaykal]

We are close, thank you !!!

To check if the process is correct I try to compare it in Nuke :

• I set my viewer to Raw to not add any transformation
• I use an OCIODisplay to call the view ShotGrading (purple backdrop)
• I redo the same transformation with the CDLTransform and the FileTransfom

At this point it does not match as I expected because we are applying a view transformation (right ?), so I try to invert these transformations. I get close but still a difference

[sbaykal]

Here the difference :