Color Pipelines & Compatibility

Blog

By: Jesse Korosi, Director of Workflow

In today’s world there are a ton of different ways to go about trying to get the best looking color correction on your dailies.

How I look at our role as Workflow Producers is that we need to think big picture.  When it comes to color, it is important to consider how different departments flow together and how we can ensure that choices made up front are compatible down the line.

One huge issue is that there are so many different software companies going about their own way to create these awesome coloring techniques within their software…But it doesn’t automate into the other necessary departments!  And I use the word automate as that is very key.  A few examples may be:

Colorfront’s enhanced coloring tools.  Awesome…But VFX can’t use them

Resolves secondary’s – Awesome.  But again, VFX can’t use them

BLG’s from Daylight. Filmlight at least has a plugin for Nuke. Fantastic. One issue, however, is that for any VFX reviews, they can’t apply this color.

The one and only method I have seen that we can always guarantee will work is CDLs.  Yes, we are restricted. However, we can at least guarantee everyone is going to see the same thing across the entire job.

I thought I would share an example of a CDL workflow we recently ran on a feature and just how many different departments were able to use our color.

On Set:

– Alexa shooting ARRI RAW

– Live grading using the software Live Grade

– The live feed had a CDL > Output LUT

– RED material had an input LUT converting RedLogFilm to LogC and then we applied: CDL > Output LUT

– The Rec709 output LUT used on set never changed and this was a LUT given to us by the finishing facility to closely resemble the P3 LUT they will be using for projected final color correction

– CDLs were then given to the lab per setup

Within the lab:

– CDLs were applied (+ the Rec709 output LUT)

– Tweaking was done shot to shot to ensure that everything matched

– These CDL values on a shot by shot basis, were put into the Avid Bins for editorial

Editorial:

– The looks were, of course, baked into editorial’s DNXHD files

– Any time the VFX Editor would request a VFX pull from us, he would export an EDL, but contain the CDL values from the Avid Bin within the EDL

VFX Pulls:

– We were then conforming back to the negative and exporting EXRs in Linear

– With each turn over for every VFX pull, we provided the original EDL that came from editorial, as well as the QT reference, a .cdl file for every shot, but now this CDL was renamed to match the VFX shot name, as well as the EXRs, of course.

VFX:

– When the VFX vendor worked on their shots in Nuke, they applied a Linear > Log conversion.  And then they had the CDL values they could turn on or off to see the intended color

– They would render two final files after they finished their work:

– Final DPX frames in LogC

– QT DNXHD115 file for editorial > with the color baked in

– The VFX vendor would provide an ALE back to editorial with the tape name populated with the file name, as well as the original CDL values. Therefore, when editorial brings this QT into Avid, they will not lose the tape name and they will also still maintain the CDL values come conform time!

VFX Review:

– Now, back at our facility, we can open the DPX frames from the VFX vendor.

– We were using a Baselight for our review sessions, so the DPX frames were brought in using the ALE that came from the VFX vendor.

– This ALE contained the CDL values, so the color was automatically re-applied in the base light upon import.

Editorial:

– Just to reiterate, as this was super important, the VFX shots that came back as QTs to be dropped into the edit now had the EXACT same color that the original dailies had.  Therefore, when playing back in the sequence again, it doesn’t jump when cutting between VFX and dailies.

Final Turn Over for Conform/Color:

– Editorial exported out an AAF and an EDL per track

– The AAF/EDL that was turned over for our conform also still maintained the CDL values.

– Once we conformed the movie, we had all of the CDL values present.  This was super useful as we had a few reviews where people wanted to watch the locked conform split screened against the reference QT from editorial.

– After the conform was complete, final DPX frames (+ an EDL with CDL values) were rendered and sent to the final colorist for color correction, as this was actually happening at another company.

– When the final DPX frames got to the facility doing final color, they loaded up the CDL values within Resolve using a Color Trace from the EDL we gave them.

– They then compared this against the QT reference that came from editorial to ensure that nothing had been screwed up on the LogC render of the final dlx frames.

– This color metadata was then accessible for reference.  (NOT a starting place, but a high resolution reference, versus looking at editorials QT ref)

Stereo Pulls:

– The stereo vendor eventually had frames pulled for them as well.

– They needed access to the color information, so we treated these pulls just like a VFX pull providing them the original pull request EDL with CDL values, as well as a .cdl per shot (renamed to match the stereo name).

Stereo Reviews:

– Stereo shots would come back in LogC and we would drop these into our locked 2d conform, therefore, we had a running 3d conform.

– We had the original CDL values already loaded from the 2d conform, so now when we wanted to host people for Stereo reviews, we were able to easily pay back every shot with the original color applied.

Stereo Conform / Color:

– Same process as 2d outlined above

So, in this workflow, the DITs color on set literally travelled (as meta data!) through: The Lab, Editorial, VFX, Stereo, Conform, Final Color.

As you can see from the workflow outlined above, there are a lot of steps to consider when choosing a color pipeline. There are always going to be exceptions where it’s not possible to keep everyone looking at the same thing. But this is where we simply need to weigh the pros and cons out. But to weigh these out, means someone needs to be on the line who fully understands how each department is going to be affected by the decision at hand.