Building Custom ‘Lum vs Sat’ Curves In HSL Using Resolve’s Node Graph

April 21, 2022

In Part 5 of our 'Visual Math' series, learn how 'vs. Curves' work from within Resolve's node graph by building your own in HSL space.


Visual Math Part 5 – Learn how ‘vs. Curves’ work for nuanced image control

The Curves family of tools within Resolve are among the most useful in the entire program. In this Insight, you gain a deeper understanding of how these tools work by building your own version – right within the node graph!

The point of this exercise isn’t just for fun or education – the point is that it expands your creative control over your images in very nuanced, and new, ways.

The ‘vs. Curves’ in DaVinci Resolve aren’t the only way of achieving these results. Learn how to ‘build your own’ so you can apply them to alternate color spaces for differing creative effect.

Understanding the math behind ‘vs. Curves’ – for creative effect

The best way to gain a deeper understanding of the ‘vs. Curves’ toolset – or any other toolset – is to build it yourself. Regardless of whether you use your own version or go back to the default for your next color grade, you are left with a deeper connection to the tool and a greater skill in wielding it.

In addition, there are hidden opportunities for achieving different visual results than what’s possible with the original tool! By breaking down how to use the ‘Multiply’ and ‘Divide’ operations in a layer mixer, you gain an operational understanding of ‘vs. Curves’. Then, you’ll see how you can wield that understanding for nuanced differences in your creative work.

Don’t just watch, try this yourself!

They say that the learning is in the doing. This Insight is definitely in that category. The setup for building your own ‘vs. Curves’ is actually pretty simple. For this reason, we’ve decided not to share my final node graph. Instead, build it yourself!

It’s easy, using me as your guide.

The long-term value in doing this yourself is developing the muscle memory. As you build this node tree, and then break it down, you’ll grow your understanding of Layer Mixer composite modes – and much more deeply than just sitting back and watching this Insight.

What you should take away from this Insight

My goal with this Insight is for you to learn:

  1. How an “X vs. Y” curve works: Its end results, as well as the math underlying it
  2. The creative possibilities of working in different color models such as HSV and HSL
  3. The importance of ensuring a “net zero” node graph to confirm we’re only affecting our image in the way we intend

Use the comments, let me know how it goes!

I love hearing back from all of you. Let me know what you think and feel free to share your variations on this approach.

– Cullen

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Homepage Forums Building Custom ‘Lum vs Sat’ Curves In HSL Using Resolve’s Node Graph

Viewing 3 reply threads

    • Jamie Dickinson

      Here’s a question /challenge… This is a really cool concept and I’m wondering if something like this could be used to create curves within a RGB Mixer? To change the way the blue channel affects the red/cyan but only in the low lights for example. I did a video years ago about the way the Quantel Pablo ‘fettle’ curves work and how this was possible, although I never really tested it enough. Seems to like an interesting experiment.

      • Cullen Kelly

        Really cool idea Jamie! You could absolutely do this. Also, stay tuned for the coming installments in this series, we’ll be tackling this exact technique with a slightly different approach…

        • Jamie Dickinson

          Great – looking forward to more from this series! Thanks

    • Pourang

      Thank you so much, Cullen, for sharing a powerful concept with a node tree. Setting up other “VS. Curves” using this method will be fun. I’m searching for those color model DCTLs you mentioned, but it would be great if  you could share a link or two when/if you have time. Much appreciated. 👍

      • Cullen Kelly

        You got it! When my time allows I’m going to try to and put together a Github repo of the various models I’ve built in DCTL..

    • Pourang

      I followed the insight and created the remaining “Vs Curves”. It looks alright and it works as expected (unless I’ve made a mistake). The link includes the nodes in the insight too (there was an error uploading the zip file).

      • This reply was modified 3 weeks, 2 days ago by Pourang.

      • Cullen Kelly

        Nice work Pourang!

    • David C

      Hey Cullen! Really appreciated this insight and have already began implementing this into powergrades for multiple color spaces. I had a quick question regarding different color models not available within Davinci, and perhaps not as a DCTL just yet (unless my search through Github or the the web was not as deep as it should have been). I’m trying to find a DCTL conversion to LCH but am having difficulties. I am willing to dive into creating a DCTL that will convert a color model into it, as well as another going out. I’m assuming if I look through a few conversion DCTLs that I can find a bit of the language to get there, but definitely would need the correct model mapping to get in and out of that space. Where could I find that info?

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