Refining the Ultra Keyer

- While I often view Ultra as a basic keyer, it does offer a surprising amount of control. Let's explore some of the most essential controls that will improve your results. I've already applied the keyer, and I'll set it back to the default settings. Now, what I'm noticing is that we have a little shadow here under the nose. And we can really refine the transparency a bit on the shot. Viewing at 100% is most useful, as you can better see what's happening. But what I'm noticing here is that we have a little bit of a shadow being cast on the green screen, and that's creating a slightly rough edge. Now, I'm going to switch the output to view just the alpha channel for a moment. And this makes it easier to visualize that edge. Now, you'll see several categories here: matte generation, matte cleanup, spill suppression, and color correction. Matte generation is the initial control that you need to tweak. This is what's creating the transparency. After that's done, we can refine it and then get into other things like color cast or spill that's left over from the color being reflected onto the subject or the need to adjust the color from foreground to background for better results. Let's refine a bit here, starting with matte generation. We'll start with transparency. As I adjust this here, you can see how it starts to bring back some partial transparency to other areas. Now in this case, that's way too much because you see details in the sweater and the skin are starting to fall through. But by refining this, we can get just the right balance, little transparency or a lot. Generally speaking, you want to get a little bit more aggressive and keep that somewhere near the middle so you start to see some falloff in details like the hair. Now, using controls for highlights and shadows, we can refine. This is a little easier to see if we actually view the composite. This is making subtle changes in the brightest areas. Not bad, but I'll just come down right to the tolerance controls which control how aggressive the effect is. By increasing this, you'll see that it starts to go after more areas. And now, let's work with the cleanup controls. Now, I'm going to switch back to view the alpha channel. And you see, we have a little shadow here under the nose that we want to remove. Using the choke controls, we can go after that a bit. You see that that starts to contract the edges. Do a small amount of choke and put a little bit of contrast in. There we go. That's helping. And I can move the midpoint a little bit as well. And that starts to favor either the whites or the blacks. And you see how that's cleaned up the shadow under the nose. Now, once you get aggressive like that, I'd recommend you drag through the image a little bit to check the edges. And then, flip back over from the alpha channel to the composite view. That's looking pretty good, but I'd like a little bit of softness in there. So, under the controls here, I can introduce some softening to the edge. Don't go too far, or you see it continues to erode. But a little bit of softness, and then even possibly backing off the choke a bit will help. And that gives you great edge detail. The nose looks clean, and I don't see the problem area of the shadow along the edge of the arm. So that's really cleaned up well. If we continue to scroll down, we see two more zones. Let's take a quick look at spill suppression here. And what we're looking for is what's happening on the edges. I'll adjust the amount of spill correction first. Setting it to a lower value starts to introduce some of the green back in at the edges there. Bumping that up to a higher value, it pulls that out. And you can adjust how much it desaturates that edge as well. If you start to see green halos around the edges, continue to play with spill suppression and the desaturation controls. Let's zoom out for a moment, and you'll also see that we have some color correction controls here which allow you to adjust things such as the saturation of the clip. We can make this a little more washed out because of the bright backdrop. And let's shift the hue slightly. And you see, we can put a little bluish color cast in there. There we go, just a slight hint. And we'll brighten that up just a little more. And now she starts to look like she's in the same outdoor lighting. Let's preview that. And it looks like a very good key. Now you may notice that it does not play back in total realtime the first time through. If you start to adjust some of those tolerance options for softening, Premiere may have to cache a few frames. But it should still give you close to realtime playback even on a laptop. And with one or two passes through, it should then switch back to realtime performance once those frames are cached. You see here that fewer frames are dropped this time through. And probably the third time through, they should be completely cached to memory. Now, this was a pretty straightforward clip, but let's tackle a difficult clip, one that has lower resolution. And I'll show you how we can really refine the controls inside of the ultra effect to get good results.