Andreas Bengtsson

jsmack
a cube lut is usually applied using a shaper space, since they map 0-1 input values to the output values. Inspecting their reference config, they use a log2 allocation space as the shaper space. Are you replicating this transform in your config? I haven't tested this config so I don't know if it works in Houdini.

Good observation jsmack. I have replicated the lg2 allocation in the Houdini config, but I am not sure whether Houdini can interpret it correctly or not.

I'm trying to implement Khronos Group's "PBR Neutral" tonemapper into an OCIO config in Houdini, but I do not get the results I want when I render with Karma in Houdini 20.0.

Values above 1 still clip to o1, where the behavior in Nuke or V-Ray standalone is as expected - a nice falloff in the highlights. SDR values (below 1) seem to behave roughly as expected.

The tonemapper is basically just a .cube LUT, and my hypothesis is that Houdini can't handle the LUT correctly. My implementation is to edit the existing Houdini OCIO config to include the info from the PBR Neutral OCIO config (with the LUT moved), but I have to admit I'm a bit of a rookie working with OCIO.

Has anyone else tried to make PBR Neutral work in Houdini?