Learn about using built-in component of Chroma key Studio to improve the key alpha matte.
- [Instructor] We're back to the unicyclist who's been chroma keyed. Let's see if we can improve the quality of the matte. This is saved out as 4_2 by the way. Now go back to the unicycle layer, and back to the Chroma Key Studio effect. As I mentioned there are built-in components such as Matte Cleanup and Matte Choker that can help us. Let's start with Matte Cleanup, I'll turn it on, expand that section, and this has a gamma, which effects the contrast of the matte, and a black level and a white level that determine what is black or transparent, and what is white or opaque.
For example let me go and turn on my Chroma Key Matte view, we'll zoom in to the bottom where we have noise on the ground, and we'll increase the black level. As I do that, the noise disappears. For example, enter 27, what that means is values between zero and 27 are pushed down to zero, so the dark gray that was there, becomes zero or transparent. I can do the opposite on white level, I can lower that to try to get rid of some of this gray left in this clothing.
If I lower it, it starts to become white. For example, 60. So now it's a bit cleaner. We'll leave gamma as is. Let's move on to the next component, which is Matte Choker. Matte Choker affects the quality of the matte edge and some of the results are only visible when you look at the final composite. So let's switch back, final composite. Now once you turn it on it works right away, so here I see that I'm starting to lose his fingers. Let's make some adjustments, there's a built-in Blur which blurs the edge in RGB, there's a Choke which erodes or expands the matte edge, and the Gray Soften which affects the softness of that Choke.
So let's see, let's try to expand the Choke so it's more aggressive. Now, more of it disappears, but I can also use the Gray Soften simultaneously, and adjust that to come up with a better result. So maybe 100 Choke, and 85 Gray Soften. There's also Blur, which again blurs that RGB edge, now if I go really high it really starts to show a white line on the edge, we don't want that.
If it's zero I see some stair-stepping. So let's just leave that at three. Now I should test this on other frames. Now, we still have a problem with our bike wheel. The bike wheel itself looks better, but the spokes are still missing. We're going to have to deal with that in a separate step. If all those edges look good-- now there is one issue here I'm not crazy about, and that's the fact there's a little bit of green trapped in some of the corners, left over from the green screen.
Now I can be more aggressive towards that, remove more of that, but it might lead to some other problems. All these components, see how they interact with each other, in other words if I turn on Matte Choker and Matte Cleanup, those settings will affect the matte in combination with the Chroma Key part and so on. So once you activate a new component, you might have to go back to an old component and readjust that until everything's balanced out. In terms of this trapped green in the corners here, what I could do is go back to my Chroma Key section, and adjust my red, green and blue weight balance.
For example, if I increase the green weight, it's more aggressive towards the green and I start to get rid of all these corners. Now that might lead to some other problems; for example, it might really start to erode the tire again, or parts of the bike seat that are really reflective. So I have to be aware that I might have to go back and forth between all these components and try to balance them all to give myself the best overall result, even though it might not be perfect now.
I think I can go ahead and live with my previous setting for green weight, I think that looks better overall, and in terms of those green corners I was talking about, I think that won't be a problem, because eventually we're going to add Light Wrap to this, and composite this on a new background that's very bright, so I don't think those will be visible. So I think this is the best overall average in terms of settings. That is one issue, you have to think about what it's going to eventually be over the top of. Okay, I think that's a good place to stop for now, I think we've improved the matte overall, and we can deal with other issues like color, and then placing this over a background in later steps.
VFX expert Lee Lanier begins by exploring shared Boris Continuum controls, and then shows how to apply stylistic effects. He explains how to work with the PixelChooser and Boris Lights, and discusses how to color grade and warp footage. He also takes you through using the Boris Chroma Key Studio and working with Mocha Pro for motion tracking, as well as how to add particles and work with 3D text.
- Overview of Boris Continuum
- After Effects preferences
- Applying stylistic effects
- Relighting with Boris Lights
- Adjusting colors
- Changing the time of day
- Warping footage
- Keying green screen
- Motion tracking
- Adding particles
- Working with 3D text