G.O.A.T. Trees: Demystifying Node Trees For Color Grading in Davinci Resolve

Introduction

This week, we're announcing a new series coming to the #KnightLight YouTube channel called G.OA.T. Trees. In this series, we'll be decomposing the Davinci Resolve node trees of some of the greatest colorists in Hollywood. As a harbinger to this new series, I wanted to write an article explaining what Node Trees are, how they're structured, the different kinds of nodes used to build the trees, how groups are used for speed and efficiency in grading larger productions, and more.

The use of nodes as a linear approach to color grading is what separates Davinci Resolve from the other Nonlinear Editors (NLEs) like Adobe Premiere and Final Cut and it also is what makes it more powerful. Davinci is not the only NLE that supports node-based grading. Assimilate Scratch also uses a node-based color grading structure. While some may consider it too formulaic, I however, being an O.C.D., linear thinker, appreciate the rigid and formulaic structure of node-based grading. I often look at color grading as a journey to a final destination (or look) and each stop along that journey being the nodes in the node tree.?

The most important rule of node-based editing is that the order in which the color correction and color grading is done matters (read: first-in-first-out (FIFO)).?

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Nodes

Let's work from bottom-up and look at what a node is first. Think of nodes as the leaves of the tree with each interconnected node able to be surgically graded at an individual level. Each node represents a particular adjustment or operation (discussed later) in an orderly, interconnected sequence to achieve a desired look. This offers a far higher degree of flexibility and control over the image not offered by competing NLEs.?

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Different Node Types

There are different types of nodes within the tree, each behaving differently.

1. Serial Node: Serial nodes are the most straightforward and commonly used node. They process corrections sequentially, with one node affecting the output of the previous one. This setup is useful for a linear workflow and creates the FIFO order of changes I discussed previously. Each node has an ingress and egress marked by a colored arrow.?Green and blue arrows serve specific purposes and indicate the direction of data flow between nodes. Understanding these arrows is crucial for comprehending the workflow and the influence of nodes on each other.
2. Green Arrows:?Forward Data Flow: Green arrows represent the forward data flow, indicating the order in which data is processed from one node to another from left to right. The green arrows on the left of the node are ingress points to receive output from a previous node and the green arrows on the right of the node are the egress output of the changes that node applied to the data it received from the previous node. Each node processes the image data and passes it along to the next node in the sequence through the green arrow. Think of each node applying its changes on top of the previous changes it was given by the previous node like layers of a cake.?
3. Blue Arrows: Data splitting and merging: The blue arrows are used to split and merge data within the node tree allowing a copy of the image data to be sent to another branch of the node tree, make adjustments there, and then emrge the modified data back into the main sequence. Blue arrows are also used for parlallel processing, with different corrections or affects being able to be applied to the same image data simultaneously without qaffecting the sequential processing in the main branch. This is particularly useful for creating complex corrections or experimenting with various looks without disturbing the original grade.
4. Parallel Node: This node type allows you to make corrections without affecting the previous nodes in the same branch. This is ideal for creating multiple correction paths that can be mixed together or compared. It's an alternative to the linear editing of the serial nodes where every node stacks its changes on top of the previous node.
5. Layer Mixer Node: This node lets you blend different corrections together, providing control over the intensity of that correction or adjustment. It's particularly useful when you want to combine different looks or masks together.
6. Key Mixer Node: Key mixers are used to combine separate keys or mattes allowing you to create complex or very precise masks by combining multiple keys in a single node.

?But why nodes? Why does it even matter and what's the value of it??

1. Non-Destructive Editing: Changes can be isolated to individual nodes allowing for an ordered approach to color correction and grading as well as the ability to roll-back changes at a node level making undoing certain changes far easier. Additionally, Davcinci Resolve (Version 18.6.2 as of this writing) allows nodes to contain versions of each node embedded within it, allowing not only changes to be rolled back at an individual node level, but also the ability to create different versions of nodes as well that allows the colorist to compare versions of different grades.
2. Precision: Node trees enable a more precise and creative color grading pipeline allowing the colorist to layer multiple nodes to apply various corrections, masks, and effects, giving the colorist not only segregation of changes, but also the ability to layer/mix those looks together as if each node are multiple transparencies layered on top of each other under an overhead projector.
3. Efficiency: The fact of the matter is, time is money in color grading. Colorists need to be able to do their best work at the fastest possible pace. Node trees are also designed to make colorists more efficient in their pipeline by allowing the color to save a "Still" of a final grade into a "Powergrade Album" that can be used to replicate the same exact node tree on future clips and projects.

Clip Groups

While each clip can have it's own separate node tree, clips can also be grouped together allowing the colorist to grade more than one clip at the same time in a group of clips that all have roughly the same exposure and color balance. This creates a far more time efficient workflow, especially for larger projects like feature length films or TV episodes. When clips are grouped together, two groups are created in addition to the individual clip node tree, a PRE group and a POST group.?

1. Pre-Group: The PRE-Group applies the node tree to every clip in the group. It's typically used to prepare footage before secondary corrections and look development. Conversion of the clip is used when the working color space isn't being managed automatically by Davinci Resolve. When in Color Managed mode, Davinci will automatically determine the capture/camera color space and gamma and convert the LOG footage into Rec.709 or the working color space of the colorist. Additionally, noise reduction is typically performed in the pre-group along with sharpening for detail enhancement and basic color correction, like white balance, exposure, and contrast.
2. Clip Group: This is where and secondary color correction is performed along with look development. Primary color correction includes adjusting the color temperature, exposure, and contrast for a "natural" look. The colorist can isolate color correction to specific areas of the image using masks, depth maps, and qualifiers. Next, the actual look development or "color grading" is performed giving the clips a unique look or style, such as split toning (E.g. orange and teal look).
3. Post-Group: This node tree is applied last after the clip group tree is applied. This typically will contain another color space transform node to convert the working color space into the delivery color space if the two are different. For example, converting an ACES working color space into Rec.709. Choosing to give a "filmic" or "cinematic" look to their project, colorists will also add film looks to the post group so it applies to every clip in that group or will even place it in the Timeline group which applies to every clip in the timeline. This includes applying film grain and texture, any fine tuning final adjustments.

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Summary

The rapidly evolving Hollywood landscape ushered in by digital transformation has affected practically every phase of production from pre-to-post. Over the last two decades, film cameras have all but disappeared replaced by digital cameras and camera-to-cloud. Now, even $80 million dollar movies are being shot on $5,000 DSLR consumer cameras. With all of these advancements happening on set, the color grading suite in post-production has had to keep up.?DaVinci Resolve's node-based approach to color grading is unparalleled in sophistication and creative control by other NLEs. In this article, I detailed how node trees work and detailing the various node types -- each giving limitless possibilities to the discerning colorist. The juxtaposition of green and blue arrows, signifying the orchestration of sequential and parallel data flow between nodes underscores the finesse inherent to Davinci Resolve. DaVinci Resolve's node-based structure gives colorists the power to craft images with unrivaled, repeatable precision, fostering a world where non-destructive, efficient editing converges with boundless creativity. Throughout the G.O.A.T. Trees series in the Knight Studios community forum and on the Knight Light YouTube channel, we will analyze the node trees of some of the greatest Hollywood colorists of our time and explain the? idiosyncratic nuances and decisions behind them with each colorist.