[Bf-vfx] Blender's colour pipeline

[Xavier Thomas]

Hi,

Good to see you here Matt. There was effectively some discussion about the
pipeline but if I recall well everybody ended agreeing that the pipeline you
set-up is OK and just need to be made "configurable", ie letting the option
to the user to force a specific color space for some specific input/output.

The open questions was:

- Wich CMS to uses? Apparently only lcms2 and OpenColorIO can handle
properly 32bit flat imagery. OpenColorIO seems to be the preferred choice
because it is oriented CG/Vfx and tightened to OpenImageIO which might make
his way into blender (Cycles). However some people where disappointed that
OpenColorIO does not handle the full ICC 4.2 spec. Personally I think it is
not necessary and people making graphics for printing (CMJK but often still
images and not animation) should do the CG in blender linear and the color
correction/composting in a program more intended for the purpose (Gimp,
Photoshop, ...)

- We need a good proposal for specifying the display profile(s), ideally one
that would work with multi-display, calibrated display and professional
studio monitors. One settings in the user prefs do not cut it. One settings
for each image viewer or compositor window/area type would not make it clear
which profile to use in the UI for the color pickers. Personally I would go
with a setting per window (real window, not area) and put it in the info bar
next to the render engine selection.

-We should take more care of the info that does not need conversion. For
example if you store world position and normals in a buffer to do some
relighting in the compositor, even if the values are stored in an image they
should not be handled by the CMS, or the CMS should recognize those and just
use a pass-trough.



2011/7/18 j.bakker at atmind.nl <j.bakker at atmind.nl>

> Hi Matt,
>
> Thanks for this clear explanation! It gives me understanding about the
> ideas behind blender's colour management. Possible steps could be:
>
> a) Which CMS to use and why?
> b) Link the chosen CMS to blender's image loading and writing (there has
> been several discussions on OpenEXR compatibility the last week on IRC)
> c) Attach to the display routines, replace colour management inside blender
> d) Apply CM in other area's like compositor, color picker, multi-display
> setup and others
>
> a, b & c IMO is a project on its own. After that d could be a simple step.
> A task that needs to be designed with care is the blender internal renderer
> multilayer openexr (save buffers).
>
> This project looks like a large undertaking to get it working in all areas
> (but also with big benefits).
>
> BTW I saw a compositor node that converted the internal color information
> to rec709 and back again. If I understand correctly this needs to be
> revisited?
>
> Jeroen.
>
>
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