I wonder if the 1.0 clamping issue happens with LUTs only, or if it will
also happen with a custom OCIO config?
Also not sure if the issue is in the OCIO code, or if it's just in
Silhouette. The CSP and Houdini LUTs work fine in Nuke's
OCIOFileTransform node (Nuke 6.3v8 from May 1012). I may just be using
an old version of Silhouette (4.5.3) with an older OCIO - I'll see if I
can try a newer Silhouette version, maybe the bug was fixed!
Silhouette isn't doing any clamping of its own, so this must be happening in the FileTransform.
Also, I bring up DPXs because if I use DPX in Silhouette, I can set its
"Interpretation" to "linear", and then simply apply the 3D LUT (a .cube
that accepts CineonLog input) and it will look perfect! However there
are a few downsides to this:
- We'd need to convert our EXRs to DPXs.
- It's not exactly a linear workflow, e.g. the "Gain" slider applies
gain in log space instead of scene-linear space.
We put the Gain transform before the FileTransform because that is what Mari does/did. I can see the reasoning of that, if the file LUT is meant to model a specific special display.
Sounds like a custom Config is the way to go.