Keying Greenscreens in After Effects

In this After Effects tutorial, we'll learn how to key greenscreen or bluescreen footage in After Effects. Software required: After Effects CS5 and up.
Course info
Level
Intermediate
Updated
Dec 1, 2010
Duration
50m
Table of contents
Description
Course info
Level
Intermediate
Updated
Dec 1, 2010
Duration
50m
Description

In this After Effects tutorial we'll learn how to key greenscreen or bluescreen footage in After Effects. Using greenscreens is a common practice in today's VFX workflow, so understanding how to get a good alpha from greenscreen footage is very important. We'll begin this tutorial by learning what a chroma key is and what we need to look out for while we shoot the greenscreen footage. From there, we begin keying a sample shot using the Keylight keyer. We'll then learn how to refine our matte and edge using the various built-in modifiers. Finally, we will composite our keyed footage over a background and learn about spill suppression and some compositing tricks to integrate our pieces of footage. We'll end the tutorial by learning a method of treating compressed or chroma subsampled footage to pull better keys. Software required: After Effects CS5 and up.

About the author
About the author

Chris is a VFX author at Pluralsight. Along with creating and recording training, he also manages the support team and works closely with the production development team. He began his career working freelance and quickly realized that he wanted to find a company where he could use his talents to help people succeed in the CG industry.

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Section Introduction Transcripts
Section Introduction Transcripts

Introduction and Project Overview
Hello, I'm Chris with Digital-Tutors, an Adobe authorized training partner. In this series of lessons we'll learn how to key green or bluescreen footage in After Effects. I'm going to use the term greenscreen to refer to either screen color. Using greenscreens is a common practice in today's VFX workflow, so understanding how to get a good alpha from greenscreen footage is very important. Now we'll begin this project by learning what a chroma key is and what we need to look out for while we shoot the greenscreen footage. From there we will begin keying a sample shot, using the Keylight keyer. We'll then learn how to refine our matte and edge using the various built-in modifiers. Finally, we will composite our keyed footage over a background and learn about spill suppression and some compositing tricks to integrate our pieces of footage. We'll end by learning a method of treating compressed or chroma subsampled footage to pull better keys. This series of lessons will take a step by step approach at the keying process inside after effects. Creating alpha or mats using green screens will allow us to composite two pieces of footage together much faster and with a much higher degree of accuracy. So with that, let's go ahead and get started.

Keying Greenscreens in After Effects
In this lesson, I'm going to hand it over to Justin in a Visual Guide team to talk about Chroma Keying, which is the basis of almost all greenscreen work. After you learn about chroma keying, we'll take a look at how to shoot green screens and then we'll jump into our compositing application. In this lesson, we will learn about Chroma keying. Chroma keying is the compositing technique of using color information to create a matte or cutout that will allow us to remove part of an image or video. You've probably heard of actors being filmed on green or blue screens and this is part of the chroma keying process. After we have the greenscreen video or film, we can use a chroma key to take all of the green in the image and make it transparent, enabling us to put our actor onto a different background. A chroma key works by looking at each pixel in an image or video and comparing it to a color of our choosing like this bright green. If the pixel matches our green color, then the chroma key sets that pixel to be transparent. You can control the range of colors to remove more shades of green for a tighter matte or fewer shades for a noisy, but more accurate matte. You might need to pull multiple keys of the single video and blend them together in order to get a nice result. So if you need to create a transparent area or remove a foreground object from its background, you can use a chroma key to remove areas of solid color.