How to use Green Screens with Adobe After Effects

This gif shows what you'll learn in this tutorial: Basic Green Screen, Green Screen with Mask, Green Screen with Mask and Motion

The first thing I'll show you in this tutorial is how to do use a green screened video over static video footage and images. Then I'll explain how to mask out areas of your green screen in case you want them to appear behind something. Finally, I'll explain how to add motion tracking to your green screen, which is useful if there's movement in your video and you want your green screened video to move along with the background video.

Basic use of a green screened video over a static background.

First, import your image or video which will be your background. For now, I'm going to use a static background, which which means it won't move and there's no need for me to motion track the green screened video. Drag your background to the "Create a new composition" icon. Then, import your green screened video. Drag the green screened video to your timeline, above your background layer.

Get the green out of your green screen (Keying).

Click on the search box in your effects window that's located to the right of your preview window. Start typing Keylight (1.2). By the time you get to the "L" in "Keylight", it'll appear in your effects panel. Left-click hold and drag "Keylight (1.2)" and drop it into your green screen layer. Click on the eyedropper in your project effects panel that's on the left side of your preview window. Hold down shift and left-click on any green area in your preview window. All of the green from your green screen will now disappear.

Re-size and drag into position.

Re-size your green screen by either dragging one of the corners of the layer in your preview window, or if you want to make it smaller or larger and keep the exact aspect ration, then click on the green screen layer in your composition window on the bottom left of your screen so it's selected, twirl down the layer by clicking on the triangle icon, twirl down "Transform" and increase or decrease the size from there. Then make sure your green screen layer is selected, left-click hold on your green screen in the preview window, and drag it into the position you want it in your background.

Refining the look of your green screen.

Your green screen might need some refining. You'll notice here that Shia is a little translucent. This means some light from the background is showing through his body. To fix this, go to your project effects panel on the left of your preview window. Next to where it says "View" you'll see a drop-down menu that's set to "Final result". Click on it and from the drop-down menu, select "Screen Matte". This will change your green screen layer to look black in all the areas that were green and white in what you want to stay visible. Here, you see that there is some white color in the black areas and black color in the white areas. This is where light from the background is coming through. In the same project effects panel, twirl down "Screen Matte". Increase the value of "Clip Black" until no white shows in the black areas, and decrease the clip white until no black color shows in the white areas. Do not raise or lower these values too much. I generally never increase "Clip Black" to over 20, or decrease "Clip White" to less than 80. When you finished doing this, click the drop-down menu again, and change it from "Screen Matte" back to "Final Result". Your green screen should no longer be translucent.

Refine the edges of your green screen.

Sometimes you might need to refine the edges of your green screened videos. You can see here that Shia has a white haze around the entirety of his body. I want to get rid of that. In your project effects panel on the left of your preview window, twirl down the "Screen Matte" option if it isn't already twirled down from when you did the clip black and white. Decrease the value of the "Screen Shrink/Grow" setting. Don't lower it too much, though, because it'll take away parts you want to keep. Then I increased the value of the "Screen softness" a little bit. If you want to keep sharp edges, then you don't have to do that.

Making your green screen match the background.

Usually, your green screen won't match the background in terms of brightness, color, exposure, etc. To adjust your green screen so that it looks more natural in its new environment, click on the search box in your "Effects and Presets" panel on the right of your preview window. Type the setting you want to adjust or select it from the menu. Here, Shia is in a well-lit room, so I want to adjust the "Brightness" and "Contrast" a little so the lighting looks more natural. I twirled down the "Color Correction" menu, left-click hold and dragged the "Brightness & Contrast", and dropped it into my green screen layer. In the Project Effects panel to the left of the preview window, I increased the value of the "Brightness", and decreased the value of the "Contrast". I'm finished with the green screen. I just pre-compose, save, add any text if I like, render my video, and convert to .gif using Instagiffer. All of those step are explained in my previous tutorials in full detail.

Placing a green screen behind an object in your background.

In the first part of this tutorial I explained how to simply place a green screen onto your background, but sometimes you'll want or need to place it behind an object in your background. To do this, first adjust the size of your green screen and put it into position as I showed you earlier.

Mask out the areas of the green screen that you want to hide.

You can see how here we need to hide part of Shia's legs so it appears he's standing behind the couch. There are curves on the couch pillows and grooves in between the pillows. First, click off the little icon that looks like an eye next to the green screen layer in the composition window on the bottom left of your screen. That layer is still there, but is now no longer visible. Make sure your green screen layer is selected, click on the pen tool from your top menu, click and drag little points to create a mask starting at the edges of the couch, adjust the curves of the mask to match the couch pillows as you go along, make points on the outer areas which won't affect any part of your green screen, and continue until you complete the mask. This will apply the mask to the green screen layer and allow only whatever is inside the mask to show and the parts outside the mask (those under the couch cushions) to be hidden. Since neither the background or the green screen is moving, this is all you need to do to make Shia appear behind the couch.

Finishing up the masked green screen.

Click the little eye icon back on so that your green screen is now visible again. Twirl down the green screen layer in the composition window on the bottom left, twirl down "Masks", twirl down "Mask 1", and increase the "Feather" a little to blend the edges a bit with the background. Pre-compose your layers, add text or any other effect if you want, save, and render the video as described in the previous tutorials.

Masking a green screen on a moving background.

So, I explained adding a green screen on a static background, but what if it's moving? For this part of the tutorial I'm using a cut scene from GTA V, and a Travolta green screen I edited so that Travolta looks more like one of the GTA V characters. In this scene you can see that there is movement. If I just place my green screen, it'll be static and not look natural to the scene. Here I'll have to do some motion tracking. I explained motion tracking in my Motion Tracking tutorial, so if you're looking for more details, please refer to that. For this gif I'll go through the steps of motion tracking briefly. I already have my background video and green screen imported. I started a new composition with my background video. Right-click on the bottom left composition window, click "New", and click "Null object". Then select your null object layer, click "Track Motion" in the Tracker panel on the bottom right of your screen, and place the motion tracker at a place of high contrast near where you're going to place your green screen (so they're on the same plane).

Motion track your background.

Begin motion tracking your background by either clicking the "Analyze forward" button to analyze the frames automatically, or continuously clicking the "Analyze 1 frame forward" button to analyze manually. The motion in this was pretty slow and smooth, so I started doing it automatically, but then it went off course, so I had to undo and finish it manually to get an accurate result. When you finished analyzing to the end of your Null Object layer, click "Apply", then click "OK" in the window that pops up. Your motion track is now saved to your Null Object layer.

Key out the green from the green screen.

Drag your green screen to the timeline just above the background layer. Key out the green as explained earlier in this gif.

Positioning your green screen layer.

I wanted Travolta to end up facing to the left instead of to the right, so I just grabbed the point on the side of the layer in the preview window and flipped the gif to the other direction. You can rotate, flip, reverse, whatever you want to do to suit your needs. I then left-click hold and drag the green screen layer to the position I want it to be over my background. Then, in the composition layer on the bottom left of your screen, left-click hold and drag the little twirly icon under "Parent" in your green screen layer, and connect it to the Null Object layer that you saved your motion track to. Now your green screen layer will move in the same direction as set by your motion tracking.

Refine and adjust your green screen layer.

For this green screen, I didn't need to change the screen matte "Clip black and white" values because my green screen wasn't translucent. However, I did decrease the value of the "Screen Shrink/Grow" a little because my Travolta has a black outline around him and the GTA V characters don't. I also increased the "Screen Softness" value to soften the edges around Travolta because they seemed a little rough. Because the characters still have clear-cut lines, I didn't soften it too much, though.

Masking with a moving Green Screen.

In my previous tutorial about motion tracking I added a mask to text that was coming out of a door. It that situation, I didn't want the mask to move with the motion tracked text, so I created a solid layer and added the mask to that. Here, because I'm going to mask a part of Travolta that's behind the chair and both Travolta and the chair are moving together, I'm have to apply the mask directly onto the green screen layer because I want the mask to move with it. Click the "eye" icon in the composition layer on the bottom left to make it not visible and so we can see the edges of the chair, draw a mask with your pen tool around the chair and the rest of the area completely around Travolta, click the "eye" icon again to make him visible, and then add a little feather to the mask as we did earlier when we put Shia behind the couch. Your green screen is now finished and if you want to add text or effects, pre-compose the layers and do so. When you're completely finished, just save, render, and convert with Instagiffer.

There are many green screens available to download for free off the internet. If you want to spruce up your gifs with added characters or special effects, you now have the ability to do it.