10-minute-grade-color-balancing

The 10-Minute Grade: Shot Balancing

June 10, 2020

In this installment of The 10-Minute Grade, Cullen Kelly walks you thru a few different techniques to quickly get shots balanced when time is of the essence


Series

Editors Note: On 6/23/20 we updated this Insight video to show more explicitly the problems with the built-in temp/tint controls in wide gamut projects (in this case ACEScct) as well as share Cullen’s opinion on the Chromatic Adaptation OFX toolset in DaVinci Resolve which spurred his development of his KELVIN DCTL. What’s more, prior to this Insight update, KELVIN was only available as part of the Colloid bundle.

Cullen has made the DCTL available for Premium members at a very special price. If you’re a Premium member be sure to log in to reveal information about this offer.


Shot Balancing

Sooner or later, we all encounter a situation where we need to get a grade on its feet fast.

Maybe you’ve fallen behind due to other projects, maybe you’ve had this one dropped in your lap last minute, or maybe it’s a small budget and you need to be disciplined with your time in order to make it work.

Whatever the reason, in these moments our success hinges on having an efficient and effective approach. Finding that ideal approach for the various aspects of our grades is what this new series, The 10-Minute Grade, is all about. 

In this installment, I’m going to show you a simplified approach for quickly color balancing your shots, covering:

  1. The vital role color management plays in helping us achieve good balance quickly
  2. Visualizing an “X” within our vectorscope to identify where we want to reposition our signal
  3. Repositioning our signal along the color temperature axis
  4. Repositioning our signal along the green/magenta axis

For our color temperature adjustment, I’m using the KELVIN tool from my Colloid DCTL tools. Colloid is a set of user-adjustable Resolve DCTLs for grading, film emulation and look creation. These are tools I’ve developed over the years for my own grading, which are now available for monthly, quarterly, or annual licensing.

You can learn more about Colloid DCTL tools, and get a free 7-day trial of the full bundle at http://www.colloid.cc.

Why use the KELVIN tool instead of Resolve’s built-in temperature knob?

Resolve’s temperature knob is designed to work in a Rec 709 gamma environment, while I prefer to work in a larger gamut log space, where the knob doesn’t yield good results. KELVIN was designed to fill this gap.

In the video, you’ll also see me adjust a node by turning off the red & blue color channels and then adjusting gain.  Why use green gain instead of Resolve’s tint knob?

Same answer — the tint knob has a more complicated response than a gain adjustment, because, like temperature, it’s designed to work in Rec 709. When we’re in a large gamut log space, the cleaner math we can apply, the cleaner our results tend to be.

If you have any questions, thoughts or something to add to the discussion, please use the comments below.

-Cullen


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Homepage Forums The 10-Minute Grade: Shot Balancing

  • This topic has 15 replies, 1 voice, and was last updated 3 months ago by Cullen Kelly.
Viewing 14 reply threads

    • Greg Greenhaw
      Guest

      why not just use the temp and tint controls on page 2 of primaries?


    • Robbie Carman
      Guest

      Greg – Cullen actually talks about this in the body of the post above – Resolve’s Temp/Tint controls aren’t color space aware and have weird behavior in color spaces outside of 709. I’ve had better luck with Chromatic adaptation but will agree with Cullen in a managed project in a WideGamut working space things can go wonky.


    • Pat Inhofer
      Guest

      I’ve updated this post to headline Cullen’s Temp/Tint answer.

      Also – in Rec. 709, the temp/tint controls have a roll-off so they don’t have as strong an effect as you approach black. I think that’s what messes it up in wider gamuts, that roll-off happens where you might not want it to. Personally, my decision to use temp/tint depends on if the balance of blacks is also off? If yes, then I got for more overall tools. If not, then I go for Temp / Tint in a Rec. 709 project.


    • Brian Singler
      Guest

      Cullen, those are red clips on your timeline. Why wouldn’t you just adjust temperature and tint in the the raw controls of the .r3d to get things balanced along your axes (which is a cool way to think about it, btw)?

      Isn’t it “purer” to manipulate the raw data rather than adjusting the data after it’s been essentially baked into your color management pipeline? I’ve always used chromatic adaption for when I have non-raw… like Arri ProRes or say a VFX clip that originated as an .r3d and now it’s a DPX or whatever.


    • clay a
      Guest

      honestly, this should have been listed as sponsored training, it is pushing a paid product


    • Pat Inhofer
      Guest

      Hi Clay. We’re a little confused by this comment since Mixing Light has a long history of demoing paid products (including Resolve Studio) and how colorists use them in their workflow. If Cullen paid Mixing Light for this Insight we would have listed it as Sponsored Content. In fact, he did not (we paid him, as we do all our Contributors).

      We also have a history of Contributors explaining the tools they’ve developed and also sell.

      As Cullen wrote in the article (but didn’t explain in the video), Kelvin is built for Log (in this case ACES) workflows – where he feels Resolve’s native temp/tint tools don’t give him the response he’s looking for. The way Team Mixing Light sees it, Cullen is a pro colorist who develops his own tools using Resolve’s DCTL language to solve problems he’s having as a colorist.

      If you can clarify how you think this Insight is different from the many that came before that also feature paid toolsets then we’ll be happy to consider integrating your thinking into our approach.


    • Davis Alfano
      Guest

      Little off topic: I notice a weird behavior when I use Temp or curves VS curves when I work on ACES (using Prores 422), I can’t figured out why.


    • Greg Greenhaw
      Guest

      Maybe one of Patrick’s helpful gradient tests would expose the issue?


    • Christian B
      Guest

      “Resolve’s temperature knob is designed to work in a Rec 709 gamma environment”

      One could do
      * CST log flavour > r709
      * temp/tint adjust
      * CST r709 > log flavour

      ?


    • Eduardo P
      Guest

      Damn, Cullen, I just love your precision in selecting the perfect tools and approach to fit in the working color space. Question: now in HDR window in Davinci 17, we have a working color temperature knob for ACEScct, dont we?


    • Marc I
      Guest

      Hello, thanks Cullen! Would it be the same to do it with one node using offset/printer lights in a logarithmic space?


    • Eduardo P
      Guest

      isn’t the HDR tint knob also color space aware?


    • Cullen Kelly
      Guest

      That definitely could work! Though one of the things I like about this technique is that it allows you to think in two dimensions (temperature and tint) instead of three (red, green, and blue)


    • Cullen Kelly
      Guest

      Thanks Eduardo! You’re absolutely right about the temp knob in Resolve 17’s HDR palette — this makes KELVIN no longer necessary


    • Cullen Kelly
      Guest

      And yes, it is!

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