DaVinci Export Linear EXR for VFX w/ LUT Round Trip - Help!-

I am a grad student in VFX trying to learn a proper round trip workflow to take graded footage shot on a RED (or any camera, actually) that has an existing grade in Rec709... Write out a Linearized EXR image sequence.

Then take that Liniarized EXR Sequence into NUKE, add a bunch of VFX, add the LUT for viewing/approval renders... then when approved, strip off the LUT, write out a LINEAR EXR Sequence... and take that Linear Sequence (now with VFX) back into Resolve, Reinsert it into the Timeline, and reapply the grade.

What I have MOSTLY works... I am using sample footage from the RED website, one clip of the girl with the Spydercheck Color Chart (Dragon 6K), and one clip of the timelapse of the 110 at night (Gemini 5K)
red (dot) com/sample-r3d-files


I am following this video as my base, since it is exactly what I am trying to do, and I've not found anything so exactly parallel anywhere else. The problem I think is, he is using v15 and I am on v16... so there might be something ... some switch or setting that I need to turn on or off...
vimeo (dot) com/433414213


You see, I'm the VFX lead on another student's GRAD FILM project, and I have to write up this procedure for Editorial and Post Supe (they go into Production next week) so I have to have this procedure worked out before Editorial finishes their cut, or I'll be holding up the pipeline.

Below is my workflow that I have written out.

It all "looks" right up until the very end... when I set my RE-IMPORTED, ROUND-TRIPPED linear footage back into my timeline, in the WORKFLOW, where I set the clip to BYPASS ... the Re-IMported Linear looks perfectly equal.

Problem: When I return the original clip from BYPASS to my timeline colorspace, I cannot get the Round Tripped clip to match... Because that Round Tripped footage is still in Linear... What am I doing wrong... ??
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---- Workflow So Far ---

Code: Select all

STEP #1 Turn on Color Management    We need to turn on Davinci YRGB Color Management. Open up the project settings and under COLOR MANAGEMENT, at the top group, "Color Space & Transforms" we want Color Science pulldown menu to be Davinci YRGB Color Managed.

STEP #2 Disable All Serial Nodes
     If you did your debayer using the only Camera Raw menu, or if you used a chip/color chart, and did not create any serial nodes, you are good to skip to step #3.

     If you did any manual primary grades using the Color Wheels or the RGB Mixer, then we need to disable those nodes.   a Ctrl+D or CMD+d on the nodes you used for each clip to disable them.  Do this for each of the clips.

STEP #2 The Bypass
   After making a copy of your sequence as a backup,  Righ-Click on each of the clip you are going to create EXR sequences for, Mouse over "INPUT COLORSPACE" which opens up a bit list of color space choices... mouse up to near the top, and set it to BYPASS.  Do this for each of the clips.  At this point, the clips in your timeline should look exactly like they did as if you had done nothing but import them.

STEP #3  Linearize the Output Colorspace:
      From the Project Settings, Color Management Tab, go to the OUTPUT COLOR SPACE pulldown and set that to LINEAR.  This will instantly make all your footage look darker.  Don't worry, this is supposed to happen.  We've just linearized all the gamma curves and converted the footage to Linear colorspace.

STEP #4   OUTPUT TAB
    On the Output Tab, under Export Video: 
          The FORMAT pulldown menu, set to EXR.
          CODEC pulldown menu, set to RGB half (PIZ COMPRESSION) <-- this is a lossless compression that will take color pixel values to 16 decimal places, which is more than plenty to preserve perfect color information for photographic images.

 ALSO: Scroll down a little under the ADVANCED setting and check on:
          Force Sizing to highest quality
          Force debayer to highest quality

STEP #5  Ready to Add to Render Cue and write out the EXR image sequences for your desired shots!   ** when you are done exporting, don't forget to go back into your settings and return your output back to its original value,
          (Most likely, the "Input Color Space", the "Timeline Color Space", and the "Output Color Space" will be all the same thing, so if you forget what it was, it should be easy to figure out.) 

 ** Note: when you output your image sequence, it may be important for your workflow to set the timecode/frame count of the EXR sequence to match the timecode/frame count of your SOURCE footage, NOT your timeline... because based on your edit, your TIMELINE frame number/timecode might change, but your SOURCE timecode/frame numbers will never change.

 ** Remember: go back into your PROJECT SETTINGS and put your OUTPUT colorspace back to whatever you were using before we started!!!

--- GIVE TO VFX TO DO WONDERFUL AND AMAZING THINGS ---

 ROUND TRIP, BACK INTO RESOLVE
When VFX sends your files back, they will be just as you sent them out, as Linear EXR.  So, we need to import them BACK into the project AS Linear (We bring BACK exactly what we Rendered OUT in Step #4)

VFX Return  Set To Linear
     When you bring BACK in the Linear VFX footage with the VFX on it, when you FIRST bring them into your Media Pool, they will look dark. This is part of the process. Davinci has by default, assigned them the default colorspace, and we need to tell Davinci, "No! These are LINEAR!"

     When you drop the new clips back into your timeline, go to the COLOR tab, and find the clips.  RIGHT-CLICK on the clips and assign the INPUT COLOR SPACE to LINEAR.

Now the footage looks just like where we were when we wrote out the LINEAR EXR back in Step#4!!

READY TO ADD THE GRADE  You are ready to re-apply the primary grade onto the clip, since it basically mirrors your raw footage (Only with the VFX in it now!) 

DONE!

---- end current workflow ---


1. Render the .exr sequence from Davinci Resolve as default setting "Davinci YRGB".
2. Import Sequence into the Nuke set "input transform" to Gamma 2.4 in the read node
3. Done

Import sequence back to Davinci Resolve
1. Import the .exr sequence to Davinci Resolve
2. Right Click on the Sequence Select "LUT"
3. Select "VFX IO"
4. Select "Linear Gamma 2.4"
4. Done

i'm circleing back to this as an editor i'm working with refrenced this post for pulling VFX plates from Arri RAW -> EXR

the basic issue with these instructions is this workflow forces RAW into display refered 709, and then exports a display refered / log encoded image baked into into a 16bit continer.. ouch....

750Ml bottle of fine wine, and. all but 10Ml are sent down the drain, an then the few remaining drips are put back in a diffrent 750Ml bottle...

i need the full dynamic range and gamut of the Arri35 for an HDR finish tho, so this is not a workflow that can be suported in my use case, might be useable for TV, although Prores444 also might be a better fit for workflow, but TV is not my show's targeted deliverable, HDR and theatrical @ P3 is

so to get RAW into EXR without crapifying it on the way:
set project to ACES
set debayer to camera (unless there's a reason to override, and the setting are agreed with the colorist before hand)
set IDT = none
set ODT = none
set ACES gamut compression to none
tag outpput. as AP0 / linear
set deliver to EXR -> RGB -> float -> compression of your choice (zip1/4 is most common)
hit go
walk away happy

there's other ways of getting there, this is the simplest / cleanest way IMHO

and might save another editor trying their best to not waste their time, as log encoded / display refered will not cut against the shots on both sides working in ACES, and displayed on an HDR device, so would need a re-do

it was caught beforehand in this case, trying to avoid future cases