Visual Math – Building A Subtractive Saturation Node Tree In DaVinci Resolve

Is there a difference in output between using a CST node and a combiner to right clicking menu a node to HSV and switching of the r,g channels? And if these two options differ only in style is there a guiding reason choosing this more explicit way? As in a philosophy, style guide or a set of best practices? As in using standardized building blocks, node tree idioms or design patterns.
Same goes to using an invert color effect vs flipping in the curve tool.

P.S. thank you Cullen. I find your tutorials extremely insightful.

Hey Jonathan! The main difference between using a CST vs setting color space by right clicking a node is that the latter only affects that particular node, not any nodes that come after it. So if I want to convert to HSV and then split/combine the channels, I need to use a CST. If I just set my node to HSV and then create a splitter combiner from there, I won’t have H, S, and V channels.

Re inverting color, I simply trust the Invert Color plugin more than my hands — IMO there’s no benefit to introducing the variability inherent in performing the inversion with curves.

Excellent tutorial! Keep these subtractive color videos coming. I will pay money to understand in depth best practices/methods to create subtractive color.

Awesome tutorial Cullen, clear and very useful. More stuff like that it’d be much appreciated!! Also, it would be nice to see how you can build a look with this technique. Like where would you put it on your node structure? Or can I use it as node to control the saturation (as opposite to Saturation know which we know it does other stuff as well). Thanks

(aka Bill Ravens) I’m a devoted follower of Cullen’s various presentations. Over the past few months he has completely affected a change to my workflow with his tutorials. The net result is not only a more consistent result, but, a much easier node graph.

Thanks for the insight, Cullen. I was just curious if you need to put a CST after all of this to bring the OCS back to its original value if this will be used in a dedicated pipeline with secondaries and look design afterwards. I would think so, since it essentially means everything after that first CST would have HSV Color space, correct? Also, if this is pocketed away in a compound node, does that Color Space stay nested away in there, or does it continue outside the nest as well?

Glad you found it useful Austin! More videos coming on this topic for sure

Great question David! No, you don’t need a CST at the tail, because we’re not actually in HSV. We’re simply calculating HSV in a separate “dead” branch, then borrowing only the ‘V’ channel, which we subtract and ultimately add back to the original image. Hope that makes sense!

My guy! Glad you’re seeing great results, you’ve been putting in the work of pushing your knowledge and asking great questions

Thanks Antonino! Yes, could be fun to demo deploying this in a practical node tree, will chew on this!

Thanks, Cullen! I think it does. It’s due to the first node being in RGB, then having the HSV Value branch layered/mixed over top, correct? In that way, we’re essentially staying in RGB since it’s the bottom layer of the mixer, but dipping into HSV just to get the parts we like to use. The “Branch” of HSV stops at the layer mixer, which is why we need to send it out to another lone node in order to have the HSV V mix into the second layer mixer, right? I’ll dive into the Resolve Manual and see how it discusses layer mixers in regards to color space awareness just to touch up on it some more, always more to learn!

David – The key to these latest Insights from Cullen (more coming) is the Splitter node. Once you flip the node colorspace to, say, HSV, all RGB operations within that node now happen within the HSV color space – but only within that node!

BUT – if you immediately attach a splitter node, you can extract the internal color model of that node and reroute H/S/V (or whichever model you’ve chosen) to R/G/B in whatever channel order you desire. From that point on in that node branch, you’re technically performing RGB operations – but upon the channels that got split out. Then, to get back to R/G/B output, you’ll either use a Combiner node to put the channel back in proper order OR you do what Cullen is doing in this series and use a Layer Mixer node to use ‘operators’ to interact with an underlying RGB signal.

Does that explanation help?

Also – here’s a series on the Splitter-Combiner: https://mixinglight.com/tutorial-series/using-resolves-splitter-combiner-nodes/

I’ll add this to the Related Insights on this post.

Gotcha! That helps a ton Patrick. I’ve never had the need for splitter nodes within my current workflow, but it’s always good to continue learning should the need to use them ever arise.

Excellent tutorial! Please keep making more of these!