VFX and the Color Pipeline
In this video, we're diving deep into the relationship between VFX and the color pipeline. Where does color fit in the post-production process? Does it come before or after VFX? Spoiler: It depends!
We'll break down how VFX and color grading often work in parallel, the role of colorists in creating the final look of a film, and how LUTs, color spaces, and alpha mattes are key tools in ensuring seamless collaboration between the VFX and color teams. From day-for-night shots to the precision of Power Windows, learn how these departments must communicate and share resources to create stunning visuals.
If you're an indie filmmaker looking to understand the importance of the VFX-color relationship, this video is for you.
Transcript
Hi, and welcome back to VFX for indies. I'm Paul DeNigris. I'm the CEO and founder of VFX shop Foxtrot x-Ray, and we provide visual effects and mentorship to independent filmmakers and creators. In this video, we're talking about VFX and the color pipeline.
Obviously, the colorist plays a pivotal role in post production, ensuring visual consistency by matching exposure and color from shot to shot, as well as manipulating the mood of the film to match the director's vision. But where exactly does the colorist fit into the VFX pipeline?
Or more precisely, does color come before or after VFX? The answer is it depends. Usually the VFX work needs to happen first so that colorists can have a clean canvas to work with. However, there are situations where color might come before VFX, especially for certain looks and effects like day for night or major tonal adjustments that affect the storytelling.
Mostly you can consider color and VFX to be parallel processes happening during the same phase of post and often passing information and materials back and forth. We've been on plenty of projects where the colorist is doing the bulk of the color grade while we're still working on VFX. And when we deliver our final renders, all they have to do is drop them into the timeline and make tweaks.
But in order for that to work, both departments need to communicate clearly.
VFX and color must work together. In general, the goal for VFX is to make the final shot look like everything was captured in camera. For example, if you're adding a CG building or creating a fully digital background, you need those elements in place before the colorist can accurately grade the entire shot. However, there are certain effects involving color that wouldn't be executed through VFX alone.
A great example, as I mentioned, is day for night, where a shot is filmed during the day and then it's graded to look like it was captured at night. VFX often gets used to add headlights, street lamps, other light sources to shots like these, but only after the colorist has established the final mood and tonal shift needed to truly sell the nighttime look.
In those cases, you may choose to do a rough grade first to help the VFX artists and leave the final color work until after the VFX is done.
The goal is to create a seamless result where VFX and color grading complement each other and not work at cross purposes.
To do that, there must be some common color parameters and settings shared between the two departments. This is where color spaces and LUTs come in. Color spaces such as Rec709, Sony Log, Red Log, Arri Log, are reproducible representations of color that describe a specific, measurable, and fixed range of possible colors and luminance values.
LUTs are critical components in both the VFX and color grading process. A LUT, also known as a lookup table, essentially maps one color space to another, making sure that the colors in your footage align with the overall look and tone you're aiming for. For example, if you're shooting with an Arri Alexa camera, your footage will natively be in the Arri Log color space, and we'll have the very muted tones associated with logarithmic or log color. A LUT would be applied to bring that footage into rec 709, which makes it more palatable to look at.
However, the VFX team, like the colorist, wants to work with that original logarithmic color for the most flexibility.
To facilitate the VFX team working with log color, the colorist can provide them with a working LUT, also known as a "show LUT." This is a temporary LUT created by the colorist to give VFX artists a sense of the final color tone and mood of the shot. They can be applied during the VFX process so the artist can see their work in the context of the anticipated color grade, but continue to work in log color.
This ensures that any visual effects created,
whether it's an explosion, a digital environment, or even a subtle touch up, fits seamlessly into the overall aesthetic of the film. The working LUT allows the VFX artist to design their effects within the color framework that the colorist is planning, reducing the risk of mismatched tones or lighting discrepancies.
The director can see the VFX preview renders with the LUT applied, but final renders will be delivered to the colorist without the LUT baked in for maximum flexibility in the final grade.
A key tool in the colorist workflow is the alpha matte. Alpha mattes are used to isolate specific parts of an image, such as a face, specific objects, or even an entire background, allowing for more precise control over color adjustments.
Colorists sometimes call these Power Windows or masks and they can generate them inside their color grading software, but VFX can also provide alpha mattes to the colorist. This is especially useful in scenes where significant VFX work has been done, like adding CGI elements, screen composites, or green screen shots.
The colorist can use the mattes to isolate the VFX work and apply custom grades, making it blend more naturally with the live action footage. Or maybe we've added digital blood to a shot. And when the colorist pushes it really far into a nighttime blue look, the blood suddenly no longer reads correctly because it's too purple.
Having an alpha matte provided by the VFX team for the blood gives the colorist an easy way to isolate just that element and bring back the red, so it reads correctly on screen. It's important to note that the VFX artists are responsible for providing the necessary mattes to the colorist. For each shot, the colorist will often request specific mattes, depending on what has been touched in the VFX process. This is a collaborative effort that can vary shot by shot as different elements within the scene might require separate mattes for optimal control. Clear communication between the colorist and the VFX team ensures that the right mattes are created, allowing for maximum flexibility and precision during the color grading process.
Finally, don't underestimate your colorist. Some things you might assume need a VFX team can actually be handled by your colorist during the grade. One example is using split screens to merge two different takes together. For instance, if you have two performers in a single shot and performer A is best in take one, but performer B did something you really like in take five, the colorist can merge the two takes together with a simple mask.
Colorists also have the ability to change the color of an object. They can pull simple keys to isolate specific colors easily, allowing them to adjust hues without affecting the entire scene. This means if you want a character's shirt to pop with a brighter blue or you want to tone down an overly vibrant red, your colorist can make those adjustments quickly and effectively.
Even stabilization or adding subtle camera shake, things typically associated with VFX can often be managed by your colorist using advanced tools in their software. Stabilization tools have improved dramatically and can be found in almost Every editing or color grading software commonly used.
So to recap, VFX and color often happen in parallel and must work together with a common language and set of parameters like color spaces and LUTs. When needed, VFX can provide alpha mattes to help the colorist fine tune the grade. And smart filmmakers know to never underestimate their colorist and their capabilities.
Hey, if you found this video helpful, please be sure to give it a thumbs up and subscribe to our channel for more insights into the world of VFX. And if you've got something to add about VFX and the color pipeline, please make a comment below. We'd love to hear from you. Until next time, keep creating and we'll see you in the next video. For Foxtrot X-Ray and VFX for Indies, I'm Paul DeNigris. Thanks so much for watching.
