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RED footage and Exporting color accurate EXRs

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Jack Chavez
RED footage and Exporting color accurate EXRs
on Aug 6, 2019 at 7:29:03 pm

Okay, here's the big picture. I'm overseeing a project that was shot with a RED WEAPON (image pipeline IPP2, RedWideGamutRGB, Log3G10). It's being edited in Premiere Pro. The typical pipeline at this facility is to roundtrip any VFX type shots (corner pinning, sky replacements, etc.) using AE and then send the locked picture via an XML to Resolve for the colorist who will then deliver baked ProRes files to be relinked in Premiere for conforming with the final audio mix.
So: Premiere>AE(some shots)>Premiere>Resolve>Premiere.

The issue is that the assigned colorist wants to keep everything as R3Ds for him to have maximum flexibility. He is rather set in his ways. He wants to grade only the original footage and then have the VFX team do their work after he's done with the grade.
So:Premiere>AE(some shots)>Premiere>Resolve>AE(some shots)>Premiere

That works okay for certain shots, but I'm sure you understand why that won't work as well for things like sky replacement because it essentially forces the compositor to take on colorist duties. It also means that in order to get to picture lock in the first place, the VFX shots have to be rendered (at least) twice: once before picture lock and then again after color.

I'd like to offer up an alternative approach to the colorist which would be to use After Effects for the VFX work upfront and render DPX or EXR sequences to be used in Resolve. I prefer EXRs, and so I've set up some tests but things are not working out as I had hoped.
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TEST 1
Using Fusion, I loaded an R3D clip with the default RMD settings and rendered it out as a 16 bit EXR sequence. Loading the EXR sequence back into Fusion, I created a rectangular mask for the R3D "layer" and then overlaid it over the EXR "layer" using a merge node. The result: perfection. There is no visible difference between the R3D and EXR. Fusion is linear by default so this is what I expect given that both the R3D's and the resulting EXR formats are linear.
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TEST 2.
I bring both the R3D clip and the EXR sequence into After Effects.

Project Settings: Depth-32 bits per channel (float), Working Space-sRGB IED61966-2.1, √ Linearize Working Space.

RED interpret footage settings:
Assign Profile-Rec.709 Gamma 2.4
Interpret As Linear Light-On for 32bpc

EXR interpret footage settings:
Assign Profile-Rec.709 Gamma 2.4
Interpret As Linear Light-On for 32bpc

Same approach. I apply a rectangular mask to the R3D layered over the EXR. This time, the images are displayed differently. While similar, the EXR clip has brighter highlights and there is a visible color difference.



I've fiddled with settings every way I can think of but keep hitting a brick wall. I've tried other working spaces, including ProPhoto RGB to see if there might be a distortion or clipping of values, Preserve RGB checkbox on and off, etc. No dice. The problem seems to be how AE interprets the footage, or I just have the wrong settings applied.

Any insights? (Yes, I've read old posts but haven't come across this particular issue, though Color space and OPENexr Delivery advice needed by Christopher Stewart touches on the output side which I haven't even gotten to yet. I'd appreciate insight there as well if you have it to give.


Thanks.


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