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EXR Workflow Questions...

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Alexander Higgins
EXR Workflow Questions...
on Mar 19, 2012 at 8:45:57 pm

Hello Everyone, I am just wondering how people are doing workflows with EXRs.
In our shop all EXRs are rendered in LINEAR, but it seems that DaVinci is sRGB. So when I bring in Linear EXRs they are of course dark and when I write my own LUT from NUKE using the color matrix I can get them really really close, but not exact, the blacks are still a hair off.

Can anyone let me know how people are using EXR's in DaVinci and if they are using LINEAR EXR's, HOW?
Are you guys using a LINEAR to sRGB LUT?
If so and its better than MINE, can I have it?

Thanks.


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Martin Wehding
Re: EXR Workflow Questions...
on Mar 19, 2012 at 11:46:31 pm

we are using exr's in a r3d workflow for vfx shots. Try and set the colorspace in the write node in nuke to rec709 instead of linear.


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Teo Rižnar
Re: EXR Workflow Questions...
on Mar 20, 2012 at 7:26:18 am

Rec709 in EXR out in Nuke will clip info and would not be the same like linear render and than lin-rec709 LUT. I will be doing similar thing soon. Will post my progress if I get somewhere ;)

Color grade reel:
Cofounder of http://nuframe.si postproduction


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Jimmy Christensen
Re: EXR Workflow Questions...
on Mar 20, 2012 at 2:08:33 pm

Since when did Nuke clip info in Rec709?


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Timor Kardum
Re: EXR Workflow Questions...
on Mar 23, 2012 at 4:19:02 pm

Try to set the R3D in Davinci to "RedLogFilm" and then export to EXR.

To be hosest: i am not 100% sure this is correct, we are still checking it, but where quite successful with it so far.

We will now test ACES and open-colorIO, lets see where this leads us...

Timor

http://www.omstudios.de


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Frank Maier
Re: EXR Workflow Questions...
on Mar 25, 2012 at 1:56:00 am

Had a similar issue with After Effects. In my case AE used a different Iso settings on the R3d files then Davinci. After dialing in the same value for the iso it was pixel-perfect...


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Jimmy Christensen
Re: EXR Workflow Questions...
on Mar 28, 2012 at 12:27:31 pm

Funny you should mention OpenColorIO. The new OCIO nodes in Nuke 6.3v7 actually clips (at 1.25) when going to rec709.
The normal colorspace converter in Nuke doesn't clip anything when going to rec709.


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Adrian Brindle
Re: EXR Workflow Questions...
on May 7, 2012 at 1:52:52 pm

Hi Alexander,
Did you ever get a final answer to this?
I have exactly the same problem and we're fairly sure we need a linear to SRGB Lut.
Or we need to get Resolve to read the file as linear.
Adrian


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Jonathan Berube
Re: EXR Workflow Questions...
on Jun 8, 2012 at 9:42:52 am

Hello,

It seems I'm facing the same challenge. I'm trying to grade full CG frames rendered 16bit Half Float Open EXRs in Linear Color Space.

DaVinci Resolve will let me import and grade away but I'm unable to find the proper sRGB Display LUT for my viewer config.

Nuke's viewer will do the proper Lin to sRGB display LUT conversion and so as RV but no sRGB LUT in DaVinci.

I guess most Colorists are outputting to Film or HDTV (Rec709) but my final out put is web.

Any hints on how to solve this?

-J


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Adrian Brindle
Re: EXR Workflow Questions...
on Jun 8, 2012 at 10:31:15 am

I didn't get any real resolution to my last post, no one offered a lut. (Still welcome if you have it)

What I did was import a scene into after effects which correctly scaled the shot.
I then exported this as a jpeg and imported it into resolve as a still.
I then used this still to build a grade on a node to correctly scale the shot in resolve.
I didn't make this as a lut but I could of I suppose.
This approximation was my starting point and I applied this to all on a node. I then graded on separate nodes after this.
The results were fine and I seem to have access to plenty of latitude.
Bon Change


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Andreas Bravin Karlsson
Re: EXR Workflow Questions...
on Jun 25, 2012 at 5:12:16 pm

I'm a Nuke compositor and do not know Resolve, but I find it really strange that a professional grading application does not have something as basic as a Lin to sRGB LUT. I've exported a LUT out of Nuke that I hope will do the trick for you:

lintosrgb.cube.zip

Let me know if you prefer a different format.

Andreas Bravin Karlsson
VFX Supervisor


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Adrian Brindle
Re: EXR Workflow Questions...
on Jun 26, 2012 at 4:19:51 pm

Thanks. I can't download this as the link doesn't work but is you can send it to me somehow it would be really useful.
adrian@airpost.tv


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Andreas Bravin Karlsson
Re: EXR Workflow Questions...
on Jun 26, 2012 at 5:10:04 pm

I'll send it to you by email as well, but let's give this another try:

4336_lintosrgb.cube.zip

Andreas Bravin Karlsson
VFX Supervisor


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Adrian Brindle
Re: EXR Workflow Questions...
on Jun 28, 2012 at 5:17:15 pm

That worked brilliantly - you Sir are a star!
Many thanks


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Jonathan Berube
Re: EXR Workflow Questions...
on May 14, 2013 at 10:40:00 am

Andreas,

Thank you very much sir. Excellence!

How did you export the LUT from Nuke?!

-J


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Andreas Bravin Karlsson
Re: EXR Workflow Questions...
on May 14, 2013 at 11:22:17 am

I used the CMSTestPattern and GenerateLUT nodes, together with a Colorspace node for the Lin to sRGB conversion. The help message on each node will tell you how to set it all up.

Andreas Bravin Karlsson
VFX Supervisor


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