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In After Effects CS5 Essential Training, author Chad Perkins discusses the basic tools, effects, and need-to-know techniques in Adobe After Effects CS5, the professional standard for motion graphics, compositing, and visual effects for video. The course provides an overview of the entire workflow, from import to export, as well as detailed coverage of each stage, including animating text and artwork, adding effects to compositions, working in 3D, and rendering and compressing footage. Exercise files are included with the course.
Now this is a lot more along the lines of the typical green screen job that you will be faced with. And I've already gone ahead and keyed this out for you, but I just want to show you some of things that contribute to a bad green screen. So, in case you have some kind of say in the production workflow, you can tell the production crew what to look out for so that could get a better key. Oftentimes, when people are a working on a film set, they are pros with lights they are pros with cameras, but they are not really sure of what we need in postproduction to get the best results. And so being able to know some of these tips to be able to pass those down the line so that when you get this footage it looks better.
Well it really pays to know some of things. So, I am going to apply Keylight to this and again I am going to click the Eyedropper and click the green. Now you'll notice they we're having some issues here. We have some light green here and some darker green here and typically for the best green screen as we saw in the last movie you want a uniform green. That's the ideal. In this case, we really don't have that so I'm just going to pick a green that I think is kind of representative of the whole, like an average. And you could see instantly, as opposed to the last movie when we had a really great key right after, that this looks obviously very terrible.
So, what I am going to do is change this to Status and when we change it to Status that way we can see the little squares here. These little squares are because of the compression artifacts. We are not getting an even key because of the way this was compressed. You could tell as I go into the Screen Matte area and I adjust Clip Black as before is that we're having a lot of uneven edges because, again, of this compression. Now I am just going to go ahead a turn this layer off and turned that Complete layer on. The Complete layer is me just so basically getting somewhat of a good key out a Keylight as best as I could, but we're still seeing a lot of jagged edges and I have some like wispy hair.
This is never going to be a perfect key because the footage is terrible. That's one thing that you can understand and pass on your clients is that you can do some great things, but you're not a miracle worker. You can't take terrible awful footage and make it perfect. Thankfully, in After Effects CS5, there is a new effect called Refine Matte and if we apply this here to this footage, we'll get some help with this bad key. It's not going to make things perfect, but it definitely saves you a lot of time in trying to solve problems. The first thing that it does automatically with this Smooth value, a default values of two here, is it smoothes the key out.
So, if we zoom in extra-- and it's going to look a little pixilated because we zoomed it so close. But here is before with the Keylight key and here is after with Refine Matte. So, it's smoothed things out considerably even though it is a little bit too smooth. I might want to take this down to maybe 1.3 or so, which is putting a little bit of a corners back in these edges here. We could also feather our matte. We could also choke meaning restrict the matte. If we increase this too much, we could see that like it starts eroding away at the edge around here.
But it's a subtle fine-tuned adjustment so you don't have to worry about completely destroying the edge of the matte, and it also goes into negative value to expand the edge if you want that too, but just be aware that it's here. Generally choking is though of kind of like a cheat. So, don't eat away at the edge of your matte unless you really need to. In this case, we might need to. I'll leave this set to a value of eight for the time being. Chatter, we talked about all of these settings when we talked about Roto Brush earlier on. But I am going to increase Chatter to hundred percent so that way from frame to frame I have less jitter on the edges of my key.
And one of the cool things about the Refine Matte Effects is that it also looks at motion blur when there is motion blur, and it decontaminates the edges from motion blur. At one point, I move my hand around pretty quickly here and you could see that there is a motion blur. And typically, this is really hard to get a clean key when there is motion blur because you get green from the background in the motion blur and yet Refine Matte somehow manages to decontaminate those edges for the motion blur. There is some junk going on here, what we could use go here to the Increase Decontamination value.
Actually it's called Increased Decontamination Radius and what we can do is increase this very slightly. This parameter is very sensitive, so increase it too much and it starts looking like that, which is not good. So, just a little bit. It helps get some of that junk out of the fingers, but all in all, I mean this is the before, and this is the after. We lost a little bit of hair, so you may have to go fiddle with this a little bit more, but all the same, we got the decontamination out of the motion blur. And again, this is what it looks like before and this is what it looks like after Refine Matte.
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