I've resumed looking into integrating OCIO into RV, now that RV's Python support is non-beta \o/

(I should qualify that with "thirdparty OCIO integration, as my affiliation with Tweak is no more than "happy user"!)


Only the very basic functionality is there currently (applying a colour transform a source), but the rest should be relatively straight forward:

https://github.com/dbr/OpenColorIO/blob/rv/src/rv/Python/ociorv.py

https://github.com/imageworks/OpenColorIO/issues/109


There's some things I'm not sure about:

1. Most important question: what should the default shortcut for "change view" be?

For example, we use "d" to cycle between the View's, "raw", "lin2log" and "project"them

Should there be a shortcut for switching display devices, or is this uncommon enough to just belong in the menu?

(I'll make sure the shortcuts can be customised by env-var or something)


2. How best to allow customising "what colourspace is this" and "what context variables for this source" functions? Particularly the former for facilities where the "parseColorSpaceFromString" method will not work

I was thinking just have simple callback functions along the lines of:

try:
   import ocio_rv_custom
except ImportError:
   in_space = cfg. parseColorSpaceFromString(path)
else:
   in_space = ocio_rv_custom.colorspace_for_path(path)

..although this isn't ideal


3. The "file LUT" does a lg10 to SCENE_LINEAR transform (depending on input, of course), so the exposure control acts correctly and so on.. Then the "look LUT" (applied just before viewer) does a SCENE_LINEAR to output-colorspace.

However the last part is probably 3D, and has no prelut, so values >1.0 get clipped.

To create the look-LUT, what series of colour-transforms should I perform?

Currently it does:

- input_space to SCENE_LINEAR (probably as 1D LUT)
- RV's grading controls
- SCENE_LINEAR to output_space (probably as 3D LUT)

Should I use the allocation vars to create a prelut? Or would I be better using the input_space like ociobakelut uses the "--shaperspace"? I.e:

- input_space to SCENE_LINEAR (probably as 1D LUT)
- RV's grading controls
- SCENE_LINEAR to input_space (probably as 1D LUT, if not, use allocation vars)
- input_space to output_space

Hope that makes sense - basically I need to bake out 2 LUT's - one from input to SCENE_LINEAR, and another from SCENE_LINEAR to the output space


4. Maybe a question for Tweak support, although I think Jim and such are on this list(?) - can RV menu items be dynamically added/removed?

I was thinking of having a "OCIO > Display Device" menu which lists "Rec709", "P3" etc, then a separate "OCIO > Views" menu which lists "raw", "lin2log" etc

The View menu would need recreated when you change display, as the lists are not necessarily the same. Is this possible?

Mostly just curious - there's a bunch of other ways the menu could be structured, which would avoid the need for this (e.g "OCIO > Rec709 > raw", "OCIO > Rec709 > lin2log", "OCIO > P3 > raw" etc)


5. Beyond the basics of "looking at an image with the correct display transform", what other features would people like to see from the RV/OCIO integration (either sooner or later)?

- Per-source context variables (would be a fairly high priority for me)
- Ability to apply a arbitrary "Look" transforms (without adding a new display-View)?
- export grades as .ccc (maybe belongs in RV itself, rather than OCIO, but would be fairly easy to export the exposure/saturation/offset/etc values as CDL)


Err, this email is slightly longer than I intended..
- Ben