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Re: RED footage and Exporting color accurate EXRs

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Andrew Somers
Re: RED footage and Exporting color accurate EXRs
on Aug 13, 2019 at 11:27:13 pm

[Jack Chavez] "R3Ds — In both AE and Fusion, I've started with the default interpretation, which references the metadata for deBayering, so to my mind they SHOULD match on the scopes, but don't for some reason. Perhaps AE is doing some soft-clipping.
Since Fusion is a default linear workspace, there is no reason to default to a softclip. BUT

Since AE is not a default "linear" workspace, and many use it in a gamma encoded way, Adobe seems to keep their presets/defaults oriented toward that workflow. Linear in AE was something they added when they incorporated CMM/ICC, which....
[Jack Chavez] Didn't know that about ProPoto. I've seen it recommended in a few different places but, yeah, in the Adobe documentation for sure.
...Using ICC profiles and a color management engine seemed like a neat idea... at first.

Here's the problem: It's not well suited to video/film workflows.

Color Management using ICC profiles was created for the purpose of going from a D65 RGB color model to a D50 CMYK color model, using profiles specific to the output device.

To do that, the image data is transformed from D65 RGB into the D50 "Profile Connection Space" (PCS) which is either CIEXYZ or CIELAB. This requires both a Bradford transformation matrix (for white point), and the matrix into the PCS (though the math can be combined). Then it gets transformed to the CMYK space of the output device via another matrix/LUT of the profile. That's a lot of transformations, but was the solution to make a "one size mangles all" solution for desktop printing and prepress.

For video/film we don't need all that. We need a LUT to display on our computer monitor what the image will look like through the show LUT (the look that is developed for the show). OpenColorIO is one way to use LUTs instead of CMM/ICC profiles, and avoid relying on color management in AE.

The problem with ProPhoto, is that it was intended for photo editing for print, which is D50, and so by using ProPhoto you can work in RGB without clipping, and also not have to do the Bradford transformation when converting to CMYK etc.

ProPhoto is good for that, but bad for Video/Film (something along the lines of using a metric socket wrench to hammer rusty nails into a Ming vase)...

[Jack Chavez] If I export an EXR sequence out of AE with certain settings it does match the AE interpretation of the R3D. Same for Fusion to Fusion. Not for Fusion to AE so far. EXRs from RED Cine-X look nothing like the original image."
This sounds like more or less expected behavior (not prefered behavior, just expected LOL).

My suggested workflow is:

Choose one method to create the EXRs, and create all that same way, then use the EXRs for the entire workflow.



Andrew Somers
VFX & Title Supervisor

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