Join Steve Wright for an in-depth discussion in this video Basic setup, part of Nuke 6 New Features.
We'll start by taking a look at the basic setup for an Ultimatte composite. The first thing we want to know is how to connect things up, so if you'll select the read note for your blue screen, you can go up to the Keyer tab, select the Ultimatte node, and it'll hook itself into the foreground input. There we go. The bg is the background input. We'll connect that up here. We'll take a look at this others in just a minute. Now I'm using a checkerboard as a test background. I've set the format to match my foreground image, and I've set the size of the squares to 16. Using a checkerboard like this is a better way for getting your initial key setup, rather than doing it over the actual background, which has different colors and luminosities that may hide defects.
So let's take a quick look at the tabs in the Ultimatte node. The first tab, Ultimatte, is used basically to set the screen color, and it has a few other controls, which we'll come back to. The Density tab is used to dial in the density of the matte, and you have controls over different parts of the picture. The Screen Correct node is actually used to dial in a synthetic clean plate. Ultimatte is much happier with a clean plate input, but you rarely get that, so Ultimatte actually creates its own internal clean plate. I can show you what that's like over here.
This is what the clean plate would like. The idea is it uses this against the backing region, the blue screen, and it has a matte of the defects in the funny panel lightings and all the other little anomalies in scenes like this, and it uses this to help pull a cleaner key. The Shadows tab is used for dialing in the shadows, but you will have to enable it first. It comes default disabled. The Spill tab is default-enabled, and here you have controls over the spill separation for different parts of the picture: bright, dark, cool, warm, et cetera.
The Cleanup tab is a dangerous tab, and you'll rarely want to mess with this because it'll undo the screen correction, but this allows you to do post- processing on the matte. The Color tab is used to color correct the foreground after it's composited over the background, and it gives you basic color-correction controls: brightness, saturation, and so on and so forth. The Film tab is another tab you'll rarely mess with. The basic story here is that some blue- screen and green-screen shots suffer from a problem called cyan undercutting, where the foreground meets the backing color, and this completes a red fringe around your composite.
This tab is designed to allow you to dial that down. All right, let's go to the Ultimatte tab and see how we select the screen color. First, we turn on the eyedropper and we select the screen using Shift+Alt+Command. In other words we're adding the Alt key in order to do the sample through to the original blue-screen plate. Otherwise you could be sampling the composited plate. I am going to switch the viewer to the alpha channel, and watch what happens as I sample in different parts of the picture.
Remember, Ultimatte is only allowing you to select one single value for the screen color, so where you sample has a profound effect on the resulting composite. We'll put that back to RGB. In our next video, we take a look at the other inputs to the Ultimatte node.
Nuke 6 New Features was created and produced by Steve Wright. We are honored to host his material in the lynda.com Online Training Library®.
- Exploring NukeX
- Working with the new paint tools
- Using the Clone and Reveal tools
- Reviewing the Keylight matte controls
- Creating Keylight holdout and garbage mattes
- Performing multipass keying
- Working with mattes in Ultimatte
- Creating specialized keys
- Drawing and warping splines
- Exploring the MotionBlur2D and ZBlur nodes
- Navigating the Dope Sheet
- Making gizmos