Green Screen Compositing


Adobe® After Effects® for Beginners


Lesson Info

Green Screen Compositing

This is something that is scary to people, a swell because they lend people are attempting to do it, and they're having a hard time with it. Well, obviously, one thing that you'll see in my eye promo there, and something that I really drive home is probably ninety percent of your success of getting a good green screen composite is in the shooting and the lighting and the materials you're using and all of that, and I really drive that, you know, into you when you read my book or watch my videos, because without that, everything else is a fix you're trying to fix something, and I'm going to go through this last segment, I'm going to show you, starting with this project, which is, um, great footage provided by pair homes that that from what hollywood camera work, and I don't know if that's dot uk or I don't think it's dot com hollywood camera work not no s on the end, just google that, and you'll find it he's provided a bunch of great educational clips and things that you can use to pract...

ice green screen with because he shoots a bunch of stuff hey has his own workshops that he does is well, but he's given us permission to use this clip, and so it may be a familiar to you you may have seen this clip in in use before, but this is a perfect example of well lit green screen well, that model ah lot of the problems that people have, like hair transparency and the clothing things like that and that's why this is this works out to be just a really good model teo to start from so going to cover a few things in this inn best practices basically of getting a good composite if you start with good footage, your chances are you'll get a good composite and why I typically don't say key because keane is a technical term that people use in tv for king out the weatherman or whatever that's typically something that's done with hardware, not with software, but everybody calls it keen, so I'll break down and call it keen, we're going to key out the green, so we're going to eliminate the green out of here and there is and reveal our background, which in this case I used this nice photo from greece I believe that's from my stock photo s o we've got this thiss foreground in this background we can use and I'm going to get rid of the green so the background commission and I come up here, I've got my layer selected, then I come up to effect, then keen and then down here to key light and key light is where all the magic happens this is built in to aftereffects it's not a third party plug in it's actually part of it and I start right here with this little eyedropper right here right next to screen color start with that tool that lets me come out here and select my background of course I click it once in voila there's uh there's an instant composite of sorts but I like tio what? It went away command let's come back green there ago I think when I did the zoom it went away the first thing I do is yes this looks good and that's a good first start but what you really have to look at is the mask or the mat that is created from that composite and this tells us a lot of things ah we can look in here and I can zoom in and I can see if there's any issues here if I look closely I'll see that there are is a little bit of noise back here in the black you see it's a little splotchy looking and I also look here I look around the head and the skin I see there's some transparency here that's a good thing because we want that to be transparent but I also see there's might be a little bit of green spill right here on her dress I don't want that in there because that means that she's going to be transparent there is going to be ghosting a little bit we don't want that in in our green screen so I'm gonna pull us back out so we can see what we're doing and I come down here to the screen matt setting and I twirl that down right down here screen matt so I've got clipped black and clip white in these two settings I'm going teo make an adjustment so before I do that I'm going to zoom back out so I'm going to just crank up the clip black just enough until that noise disappears up here in the corner so it's just a few little notches up and I'm going to do the opposite with the clip white I'm going to come down just a little bit till that ghosting goes away right in here so just down a little bit because I don't want any of the green on her skin teo make her transparent so now I can go back out and look at my final result and I can see I've got pretty good uh composite there it's not bad it's still because it was done in a studio in the background was done outside. There are some things I could do to kind of make that bland a little better now I've got one here that I've already done and I've got a few uh a few options here I can try different backgrounds and play with some different color corrections on those and that's probably where I would start um I've got my levels here where I can play with the levels and I can just like in photo shop I can use similar settings in after effects on some think so I've got my levels which let's start from scratch here let's get rid of that one and just so you know where to find them so I come up here to effect then color correction and then I come down here to levels and I'd like to use levels because it's built in it's not a third party thing and if you're familiar with photo shop it works exactly the same way so you can play with your overall tones your saturation your your gamma all of that I go into here and I can either like lighten it up just a little bit bring it so it's not quite his contrast you bring my contrast down a little and then I can come into my individual channels and I can start adjusting my foreground and background so I can try to blend in match that way so I probably want her to remain fairly neutral there because I don't want her to go to to read or to blue I might come down to the blue and just kind of play with it again this is subjective you go to blue, she starts looking pale you go to two yellow and starts looking green so it's a very subjective thing is to the background how you want to match the lighting, the color of the saturation all of that so you play with your levels just like you would in photo shop and then you could do the same thing with your backgrounds. Well, what was brought up earlier is how do you get a little more depth in your depth of field or fake the depth of field? And this is where I like to play with this a bit, so if I take my background and I come up to my effect and then I come down here to blur and sharpen and I do my camera lens blur, then I applied that by default comes up with the blur radius of five and if I crank that up, we can see that we're going really ridiculously out of focus, which could be a cool effect actually in something like this or we could do what I have mentioned it earlier and do kind of a simulated rack focus. So what I would do in this case is this is about toe twelve seconds long maybe I'll start with her blurred and then bring in the background again we're going to introduce some key frames so most your plug ins have these little key frame a ble items properties in there s o I'm going to just affect my blur radius across time here, so I think right about in here around oh, the four second point I want to set a key frame for my blur radius and that's just a quick way to get to it. If I come down to that layer I hit e for effect uh, then I control down my camera lens blur and there it is there's my first key frame it's right there on the timeline. So that's where it's going to be at that full effect in the background at that point. So I want to make sure that it's at the effect that I want let's go to like, you know, nineteen, maybe so that's going to end at that point and I'll come over here to about three seconds and I'm kind of going to come over here and click zero so that way it goes from zero to nineteen. Now what I'm going to do to make that, uh, work just the opposite is I can do this quickly. I could just select the effect right on the layer copy, command, see or control see if you're on a pc, then I can come up to my, uh top player the one that's been green screen and I can hit paste and that's going to duplicate that effect right on the on the stack I come down here and I look at my effects and see, there it is I got key light first then levels and now I got the camera lens blur well, I don't want it tio move at the same rate as the other one I want it to be just the opposite so what? I'm going to do it because I have these key frames that came with it I'm going to move that what was the first key frame for the background? Moving it right to the same place at four seconds and I'm good drag this one back here too three seconds so what I've got is she's blurred while the background is in focus and then as I do that little pull through there it's going to bring the focus to her so let's do a ram preview on that and you'll see what the effect really looks like that's enough so we see if we got this like simulated rack focus there so it looks like the camera lands is really, really shooting a live set here and this is part of what brings things into believability it's a matter of making sure you pick if you've just got green screen footage and you have to make a background match, you don't have the preplanning capabilities, then you have to do a lot of tricks like this to make that work but something like this really helps to sell the shot this doesn't look is much like a composited shot is just somebody stand in front of a green screen of some arbitrary background behind her this's you know, very usable now one other cool trick uh that I like to do iss and this is something you actually use in the background I mean in real world is to change the backgrounds quickly the client says no she can't be in greece she has to be in the desert so how we do that and still apply all those attributes to it? Well, one quick way to do it is to come out here in your project panel I've got all of my, uh blur settings everything on that background maybe I had animation or something happening I just need to replace that background file very quickly and leave all the attributes to it so I just select it and I come out here to my project panel and that I hold down the option or all turkey and I click and drag it over that selected background file and then let go and we'll see that it automatically replaced that file now I've got a little issue here with scale so I'm going to go up and scale it up a little bit but that's not animated so that shouldn't be an issue so now when I uh render this back, it'll have all the same effect to it and everything. Um, that the that the grease photo had so and that will do that rack focus and there we go. So that's a really quick, you step one, two, three type of process of going through, making a believable green screen composite with just with perfect conditions. Okay, the next step in green screen compositing is dealing with things that maybe they're not not perfect. You've got to deal with part of the set or other other things that are showing up. So let's, take a look at here. We've got this is a green screen shot that had motion tracking marks on the background because the camera's moving a bit and this is the same lady that beat the guy with the frying pan earlier, so we've got these other things in the set, we have to get rid of that stuff, so what we have to do is actually create a mask out of that. So let me duplicate this real quick, and I'll hide that one layer, and what I'll do is I'll get rid of the mask here, it's already in there, let me get rid of it so we can draw a new one, okay, so here's, my green screen composite basically, I've got think e light has just turned off on it. I've already done all of that, but I've still got that tennis ball and all that other stuff is out there, so I need to do something what they call a garbage matt and that's done with the pen tool creating a mask and this is a great tool for doing this type of work. I just select the layer that I need to draw mask around, and so I just start by clicking the pen tool, which is right up here, and I click right on screen here and then I can kind of work my way around here and I know he's gonna stick his head up there down where I can get to it, so I just draw this around just like I'm in uh, illustrator, whatever dress draw these busy acres there and I've made a rough garbage matt and they just call it that because it gets rid of the garbage. The beautiful thing about masks is that we can animate them, so just like everything else, I've got a little stopwatch here so I can start with my first frame. I'm gonna go back to my selection tool here, and if I shift select one of these little marks here and then selected again, that lets me just get this one point so I can kind of move this around grab these points and moving to where I want him and then I can come down in time and she's okay she's moving that way but it's getting a little close to head up there I'm going to move this one here move that up a little bit move this over a little bit still want to get rid of that marker then come over here and it's getting a little too close to her and and I just come on down the line this is called rotoscoping folks were doing roadwork and that just means you're you're creating uh a mask over time so instead of just doing green screen you're doing roadwork so this is ahh beginner's guide to rhoda work so you just kind of scrub through and see what's happening cia have tto match that up where he's standing up her shoulders kind of touching there so I'm gonna have to move this over a little bit and it's going to in between all these key frames it's going to automate whatever emotion needs toe happen here we go and you want to get paid by the hour if you're doing roadwork right yes you do but nobody will do that it's usually paid by the shot so you have to make sure that something balances out there for you but yeah this again this is like doing that tracking the bird across the screen it's um it's a little bit tedious and but sometimes necessary especially if you're trying to shoot the stuff in your bedroom or you know backyard or whatever you're going to end up doing some of this work to get rid of stuff you don't want so it's important to know that you can move masks and help your green screen project out of it okay he's moving up a lot I'm just kind of speeding through this now so we don't have to spend all day watching jeff do rhoda work ok and she's okay there and then harry comes up a little more got to keep an eye on your motion scrubbed through make sure it's tracking okay so we're starting to see some other garbage but for now I'm not too worried about it just gonna let it go and and he backs up in the camera moves and what's happening here got to move a little for a shoulder okay so now I've got this road o in here I've already done my green screen uh key light so let's turn that on and take a look at that I've also got some levels and their did some color correcting already to match the background so I was able to cool it off so let's go back to this and see if we can render this so we can see our end result now notice that I already had my tracking done in the shot I used those tracking excuse me tracking markers that we just masked out to be able to move this background so if I go to pee for position you'll see that it's got key frames and it was actually tracking those black tracking markers we just hid with the garbage man, so that is how I get the background to look like it's. Actually, part of the scene is by using those tracking markers that's why you put really predominant tracking markers in your background so you can, uh, use them toe move your background and get a little better composite so some questions have come up good. Can we do say a couple words? First question I have here is from todd, australia who says is there a difference between a green screen and a blue screen? I've seen this question so many times I feel in the last few years yes, indeed one is blue and one is green that's the first difference the reason why you would have to they started off with blue screen and that was primarily for film and film stock thie composite er's for that worked really well teo separate out the blue channel is a very thin channel of of blue in the spectrum for film so they able to separate that out really easily they went to green mohr when they went to video a special with standard definition because green is also the luminous channel in video I'm getting technical because I really need to answer that question correctly but green green has separated rgb we've seen that a bunch in photo shop we see that in after effects of the rgb so the g part of the rgb is the luminous that's where all of the black and white information is that's where the brightness the contrast all of that is in that channel it also carries the green color information so it has the most information in it that out of all three channels s o that's why they started going with green of course cameras now are capable of shooting much higher resolution they've got more pixel depth in the color range of the sensors they're still getting better but green is just such a standard because that bright green doesn't really exist that much in nature you know? So in people unless you're wearing green it doesn't exist so it also is very easy to key out people in animals and things like that with us that's why green has been kind of the standard but if you have an object that's green somebody's gotta wear green in their outfit or their costume or whatever uh or you've got a green object maybe it's plants something like that then they will use blue they just have to put a lot more light on it and make sure that they've got really good separation between the two thank you for an answer. I wondered. Yeah, so just inspect hopes you understand his questions. How dowe ikey blurred background. I shoot on big sets, so the green screen in the background has a feathered edges and it's hard to get a smooth key. Not quite understanding that just because it sounds like hiss feathering is between his foreground in his background. So it's a deal? If that's the case, then he's gonna have a lot of trouble with that. But with that said, key light is pretty amazing at understanding that because you get something like motion blur, which is somebody's hand moving in there shooting at film rates, which is twenty four p or twenty four frames per second there move somebody's moving their hand quickly in front of the green screen it's going to create motion blur. So what you get on a single frame is this big, fuzzy hand. You know, you get this blur of this blob and somebody's arm is moving it's just a big blurry blob. Well, you need to make sure that the keir software that you're using is going to be able to recognize that and just pull out the green information but allow all of that blur to stay in there, and if it doesn't, then you have to do what I just did here and you're going to have to go in there and roto all of that out and that actually is a good lead into our next project to show something like that uh in the case so let's go to the very next project because this one and let's see let's hide this because I want to make sure I grab the right project for this now this project is actually one that is yes and it's looking for real smart motion blur which I don't have installed on this machine so we won't see all of the effect in its entirety this particular project is one that's in the green screen video workshop which eyes part of the grand price winner today the video workshop that is going to be available also with an updated version eventually with peach pit peach pit video is going to be handling that whole thing so they're getting the whole new green screen master class I have to give them a shout out for this because this is one of the lessons in that as well so I've got this guy jumping off uh this is actually a roller coaster and he's jumping off and the intention was to green screen the guy we can see it pretty poor leader it's got wrinkles in it it's got shadows hey jumps away over it it's just kind of a nightmare so what do you do with a shot like that? Well, we have to do several things. The last thing we do primarily is the green screen portion of it so you can see there's a lot of motion blur there's a lot of things going on well, I'm using something that is called the road o'toole rodeo brush tool and again that's probably a little more advanced than we're going to get into with the beginner's class here but just to show you what can be done with compositing and let's see here what I've done here is a couple things again everything's on, eh? On the timeline here with key frames so let's, look here at our mask first for the very first layer and I've got this mask you see all these key frames for it? What he does is he breaks through the board there so you can see that I just had to track the board all all along there. So if I come up here and I actually solo that one frame out, this little icon down here in the bottom left this little round ball there that lets you solo out that particular layer just a little f y I there so I'm soloing out this layer some hiding everything else and I can see what's happening on just that layer alone you can see I've had to make my mask follow that board that's flying off as he's breaking through it so we can see that's going through there and it follows him now it's kind of a kind of a sharp harsh edge that I've got on it because what I was doing is after the fact I was using really smart motion blur and that adds in more blur to it because it's something that's actually moving so that's missing because we don't have the plug and installed here again we've got another mask which this one doesn't move because the camera's not moving so that just masks off the rest of the railing and then I've got another one that's a shape layer which is the rope and I just took a line tool with the shape player let me zoom in here just a little bit and on that shape layer I've added a layer style which is bevel inem boss just like you'd use in photo shop and I've given that just let me click off it for a second here see if you can see if I really zoom in here you can see there's a little bit of an edge on this rope I've gotta light direction on it and I just cheated and used a layer style on that to give it some cem curvature and some depth and again cheating is is more than okay in this type of work so this is my intermediate um rodeo on this particular that I don't think I've got rhoda brush on this not not yet. This is it here that's my second one so this pass has the guy is jumping but he's got the rodeo brush already uh applied to him and I can't really go into all of the details of the road a brush but it's basically it's this tool up here the rodeo brush tool and let's see if that information is on this layer here I mean zoom out and see if by chance that is on there again I'm not sure what level this is and maybe it's in this one here because I do have it on one of these uh no, it isn't it isn't in this one so this was actually a project file teo to pull that out, I was hoping that the road oh information would show up here but it's it's not for some reason, but the roto brush basically I can show you here quickly what it does so you have to actually double click the layer and work on the layer itself. And so let me zoom out just a hair. So I want to roto this guy and I don't want to have to sit there and trace everything he does well, the rodeo brush does a lot of that for me, so I just come in here and I click around on just somewhere inside him with this brush and it goes out and looks for the edges and it does a pretty darn good job of just finding the pixel edges for me so I can use my alter option key and say I just want to d select this part here because that's not part of what's moving okay and then I can play forward and it should find the edges and it misses a little bit here and there so I kind of lost his head there is this head pokes up I just go in there and say that please at his head and it does pretty good job and space forward let track a bit um it starts to lose his arms correction here and I'm just doing this very loosely of course if I was spending a lot of time with it I would take a little more care with it but this is just kind of gives you an idea how much this does automatically for you uh it's pretty amazing that's a very helpful tool that's the rodeo brush so what I do is after I go through this whole scene here with the roto brush and let it find its way it's way then I'm able to apply the the green screen to it the great key key light to it and be able to pull out a decent math so let's skip ahead here just a little bit okay so what I've done is I've got my mat, and what I ended up doing was making a black and white movie of it actually isn't is color, sometimes I make him black and white, sometimes I make them color, and then I go into duplicating it and create a, uh, another mat from from the original matt, I'm getting a little bit ahead of myself here with this one, because this goes down an area I'm trying not to take you to deep into the compositing effects, because this gets a little more complicated, but let me just skip ahead to the final here, because this is where everything's in there so we've got our matt everything's been color corrected, so you see our key lights there, real smart motion blur, it tells you, it's missing that's sad, but it's a great plugin. Trust me, it's! Great! Then we've got our boards and our railings and the rope in the background and let's, just do a quick ram preview here and see what the scene looks like without the motion blur added back in, and we can have a little more believable scene of this guy jumping off with a rope off the edge of this scene, so that's a little more complex, that's, using all the different tools for compositing in this one scene and that's, why my more advanced training goes into that direction for people who are seriously doing compositing like this we're using masks with key frames were using the rodeo brush which is a built in feature we're using the rope well is the shape tool with motion blur and you combine all those different things those are all touching on things we've covered earlier and again it all comes back to key key frames you're looking at the bouncing ball we go all the way back to the very first thing we cover today and we do the balancing ball and that's you know that's the root of it all how do you how do you manipulate those key frames the same way you manipulate all of these key frames? So even though we kind of went to a more advanced level at this point this just shows you that even the more advanced features of the more advanced compositing techniques use a lot of the same basic principles there just a little deeper in so I'm going teo do you have questions popping up that relate to our green screen in any way so let's go ahead and take those before going any further that'll help us okay moon set fly says jeff, should you try to stick with blue and green for king or would it be better to use a contrast for complimentary color so what you don't want to keep? Um well obviously blew in green screen are them the major key colors? If you were there times where you may want to use luminant ski, which is using a contrast ing white or black background, depending on what your contrast in color is, I've used luminant skis when I've I had nothing else to work with, and that's typically when I've got somebody's head is in the sky or something on and it's not blue it's a, you know, like a grey overcast sky, but they had dark hair well, they can kind of make a mask around their head and do a little luminous, keen or luminous masking just on their head again. That's a little more advanced features, but that is definitely an option. Typically, if you're doing a scene in your shooting a scene you want to use, the stuff you know is going to work that's typically, why you want to use a green or blue screen if you're going to do a full scene composite when you don't have a choice and you're given footage and you have to remove something, use every trick in the book to get there that's kind of what we had to do here cool, really cool from new york city asked how dependent on resolution is all of this? The more is better, you know, garbage it is garbage out so if you've got your more resolution this actually the original file for this was a four k file right out of a red camp so I had a lot of detail a lot of information that's you know, four thousand pixels wide it's it's a lot of information. Luckily, the final print on lee went to about two k so we're able to have all this data to work with and then squish it down everything all tightens up really nice and clear of the end so resolution helps the more the better the more information you have to work with definitely the better how long have you been doing green screening? Um green itself has been often on for about, you know, fifteen, sixteen years I was doing blue screen with some, uh, preproduction work for film earlier than that and again so much of it it's like self taught I because I really didn't know what to work with. I was just trying to make things happen and I was doing blue screen on some pre visualization stuff for a couple of movies and it was then done because after effects was so new at the time that I would use after effects to assemble all the stuff that I did in photo shop otto I was using plugging in photo shop was using two or three other utilities I cobbled together my own workflow, and we made it work somehow. But since after effects has such great features, and they have for a long time now, um, they've just made it easier and easier and easier for people to use its more accessible to the average person. Now. So that's, why it's becoming more popular for people? You can get a portable green screen, shoot people to do that, dear little web videos, and it really isn't just for the pros anymore. I mean, average person can shoot, and it produced a decent looking green screen and have professional results cool. So one more question west would like to know for beginners. What your best advice on getting rid of the green cast? Um, that's, actually, well, for beginners, it's a little. A little trickier depends on it. Depends on how it's shot because there's so many answers to that question. The first answer is, if you have, if you have the opportunity to take care of the problem before it's a problem that's your best bet, and that means getting the person away from the green screen. Ah, lot of times people will just stand right in front of the green screen because they see the weatherman do it well, I can do it, too, and that's different because the weather man, they're using hardware keen and they can deal with all of that and it's a little different technology than trying to do it in post in software. Eso getting the person away from the green screen to eliminate the spill in the first place is the first step. That's. The first thing I would try lighting the green screen correctly getting the person at least eight feet away from the green screen and lighting them separately. That's going to be your first bet? Uh, if that if that ship's already passed, it's already sailed and you just have footage you have to make make work. I deal with that in some of my workshops as well and in the book, but there are settings in key light that you can use that will help eliminate some of the spill there's. Some spill suppression settings. There are still suppressor plug ins you can try on, then there's a different, more advanced way of stacking layers and using using masks and mats it's a much more advanced process. But typically your green screen plug ins have some kind of spill suppression in there that you can try to doctor things up with a little bit, and that helps.

Class Description

Adobe® After Effects® for Beginners is part of our special week-long event Adobe Creative Apps for Beginners.

Join author and Adobe® Certified Expert Jeff Foster for an in-depth tour of the industry leading program for creating motion graphics and animation - Adobe® After Effects®. During this course, Jeff will teach you how to import your images from Adobe® Photoshop®, create engaging motion graphics and export them so that you can share your work with the world.

Adobe® After Effects® software lets you deliver cinematic visual effects and motion graphics within minutes. Plus it allows you to extend your creativity with built-in text and shape extrusion, mask feathering options, and a fast, easy-to-use 3D Camera Tracker.

Software Used: Adobe After Effects CC 12.0