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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
Skill Level Intermediate
Okay, the cp input, that's your clean plate; gm, that's the garbage matte; and hidden over here is hm, which is your holdout matte. So how do we use the garbage matte? Well, looking at the original blue screen, we can see that the blue screen doesn't cover some portions of the background. So we make a garbage matte that covers that part of the screen that we want to clean up and then we hook that into the gm, or garbage matte input, of Ultimatte and voila! Get a nice clean plate.
The holdout matte here, let's see how that's used. And we'll look this up here to reveal that, okay. Let's take a look at the alpha Channel of this gal here, and we can see that her shawl is extremely transparent. So let's say that we needed to do a holdout matte to fill that in. So we would draw the holdout matte with a rotor node and then hook it up to the hm holdout matte input of Ultimatte, and boom! A nice solid matte. Of course you're going to have to roto that for the whole shawl, but nevertheless, that's how you hook in your holdout matte.
Let's re-home the viewer, go back to RGB display. So we can take a look at the output mode on the Ultimatte tab. The default output of the node is composite, the foreground keyed over the background, but you can choose a premultiplied output. And of course, here, we have the alpha channel. So this is a four-channel premultiplied image. We'll go back to RGB. And you can choose the unpremultiplied, which of course is hideous and awful, so we'll go back to the composite, a much nicer- looking presentation.
Now let's take a closer look at the recommended workflow for setting up an Ultimatte composite, plus a demonstration of what each tab does. I've reset Nuke so we can step through the recommended Ultimatte workflow and see how the Film tab and overlay features work. Step one, as we saw before, was you select the eyedropper to sample the screen color. Make certain you don't sample any of the shadows. So again, Alt+Command+Shift+Drag to sample the screen color, which then goes up here. Now this is the point where you'd check for the cyan undercutting.
We'll jump to the Film tab, zoom into a part of the picture, because remember that cyan undercutting will put a red fringe around things. Now the Film tab doesn't work until you enable it, and I'll show you how it works. I'm going to punch in a strength of 300 in order to exaggerate the red fringe. So as I toggle this on and off, you can see that red fringe come and go. You have adjustment to shrink it, adjustments for transparency, and you can dial it in the brights and the darks individually.
So I'm going to disable that so we're back to our original plate, because this particular one, although it had the red fringe, it wasn't very severe. So I'll go back to the Ultimatte tab and re-home the viewer. After you've got your screen color and done the Film tab as necessary, the next step is to refine the overlay. So let's take a look at the overlay. Here is the overlay pop-up. By default, it's off, but you can choose screen or subject. Let's start with screen. By the way, there is a duplicate pop-up list right here.
So what the overlay is showing you is the backing region that Ultimatte is going to repair using that synthetic clean plate. We can refine the overlay by selecting the plus, and now if we hold down Alt+Command+Click and drag, we're telling it we want to add this area to the overlay. If part of the overlay covered our characters or subjects, we could hit the minus key and click and drag to select that. Next, we can set the overlay to subject, which of course puts the overlay on top of the subject.
We can then use these plus and minus keys to add or subtract the overlay off of the subjects as well. The important thing to realize that these overlay plus and minus strokes are in fact adjusting the screen-correct parameters. Here I'm going to reset the screen correct, and I'll set the overlay to screen, and now when I hit the plus key, watch what happens to the screen-correct parameters. As I click and drag, you see, the parameters changed. I'll reset that again and show you that you can actually accomplish the same thing by adjusting the sliders themselves.
This slider will shrink the overlay, and these sliders will adjust it in the darks and the brights, and so on and so forth. I'm going to reset that and dial my reds back small again, so I can show you the Orphans button. What's the orphan? Let's take a look at some orphans. Orphans are this little leftover bits and pieces that it wasn't quite able to clear out. So the orphans pop-up allows you to choose the radius, if you will, of the kernel. So if I set it for Medium, you see the orphans got smaller. Some went way.
If I set it for Fine, they come back, a little too much, so my best setting is Medium. Okay, we're done with this Screen Correct tab. We'll go back to the Ultimatte tab and set the overlay to off and home the viewer. Next, we'll take a look at the Matte tools in Ultimatte.