That was a tease Aaron ;). Sounds great you got it working in your
pipeline though. The thing with the RED gamma curves is that they are
often used for offline editing, and what happens is that directors
gets quite attached to the look compared to say a Rec709 viewing lut
in Nuke. I haven't found any documentation on the Redline stuff, but
I've heard it from different sources.
Jermey, I will send you some files off list. Would be superb if we
could get it working within OpenColorIO.
Cheers,
Simon
2012/3/22 Aaron Weintraub <aa...@mrxfx.com <mailto:aa...@mrxfx.com>>
Hm... I thought I had mentioned it on ocio-dev during the "Got Lut
Formats?" thread. But it's not exactly your run-of-the-mill LUT
format.
We've kind of cracked it, but it's been tricky, and really only
works for us in our specific use case. There are a lot of
parameters in the RMD files, but only some of them get used,
depending what colorspace you're using to decode the R3D files.
When you look through the XML, you see a whole lot of information
that looks like it would be useful, but it turns out that most of
it is ignored. Not to mention, the colour science behind what
each parameter does is totally in Red's black box SDK, and it
seems to change slightly with every version of their software, so
keeping up is a little bit difficult.
Our scenario is that we receive DPX files in RedLogFilm
colourspace without any metadata applied. Call these the "raw
scans" where the only thing you need to know when decoding is what
ISO and colour temperature the camera was set to. Typically (and
hopefully) these are set and locked down once for the show, or
perhaps there are two or three variations for different
environments (kind of like choosing your film stock). We work on
the log material and then want to apply the RMD at the end for
delivery back to editorial, while keeping the ungraded shots clean
for delivery to the DI (since the RMDs, while useful for dailies,
are basically tossed when the DI session starts so they can grade
from scratch. This isn't always the case, though.)
The problem is that the RMD can only be applied at the time that
the R3D is decoded, using either RedCine-X, Nuke, Hiero, Scratch,
etc. Simon's mention of Redline being able to turn the RMD into a
LUT that can be applied after the decode is interesting though...
I haven't heard of that, and if it works, that would certainly
solve this whole issue. RED themselves have told me that this
wasn't possible, though this was like 8 months ago, so much may
have changed.
What we ended up doing was taking an R3D, decoding to RedLogFilm,
and then figuring out how to achieve the effects of the RMD
parameters using standard Nuke nodes. This was a bit of a data
collection experiment, wedging out increments of each knob to
absurd extents and fitting curves to figure out exactly what they
were doing, and then deciding what node to use to get the same
result in some simple, predictable fashion. Wrap all that up in a
gizmo that looks up the correct LUT for the shot from Shotgun,
parses the XML, and then dumps the parameters back into the gizmo
to apply the various colour corrections. It actually works really
well and saves us a ton of time we'd otherwise have to spend
creating throwaway grades just to be able to submit shots to
editorial (though they will help get your shots approved... )
It's not totally 100% though. I'm pretty sure that when you apply
the corrections in the R3D decoder (either manually, or looked up
from an RMD), they are wrapped up in the full decoding chain that
makes it impossible to really duplicate the result perfectly. As
well, as Nuke's tooltips accurately state, the RED SDK returns
16-bit integer data from its colour correction operations instead
of the nice floating point workflow that Nuke has.
If you've read this far hoping for some code snippets, I do
apologize. I'd love to share it, but I'm probably not allowed, at
least at this time. I can tell you that it's definitely possible
and it's a fun science project to get it all working. Happy to
share tips and answer questions. Sorry for being a tease :)
-A
On 03/21/2012 12:27 PM, Jeremy Selan wrote:
This is the first I've heard of adding .rmd support to
OpenColorIO, but by all means if you send me some example files
(off list) I'll be happy to look into it.
-- Jeremy
On 03/21/2012 02:46 AM, Simon Björk wrote:
Hi all,
I remember a few weeks back there was a discussion of creating
viewer luts for Red r3d files using the sidecar .rmd
files. Apparently luts can be created using Redline, but I
haven't found any documentation on this. Has
anyone successfully created a for example lin2Redgamma viewing
lut? Maybe OpenColorIO could be extended to read rmd files?
Cheers,
Simon
--
--------------------------------
Stiller Studios
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Stiller Studios
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Stiller Studios
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