Chapter 25. GreenBlue Screen Keying

Chapter 25. Green/Blue Screen Keying

As you learned in the last chapter, keying involves replacing elements of one image with those of another. Green and blue screen keying keys out the green and blue information from one image, making it transparent so other images can show through. Using green and blue screen keying techniques, you can make a person appear in different locations or environments. In the Lord of the Rings films and the last remake of King Kong, for example, green screen tarps were hung up around actors and blue screen sets were constructed to enable full flexibility for incorporating computer-generated background elements in hundreds of shots.

In this chapter, you will learn how to set up and light a green/blue screen shoot, as well as how to key out the recorded green/blue elements in Premiere Pro. The first lesson provides an overview of setting up your shoot and of the tools you can use to make green/blue screen keying much easier and more accurate. The second lesson takes some imperfect green screen elements from Chapter 27's live multi-cam shoot and shows you how to key out the green screen to introduce different backgrounds for the material. You also will use Garbage Mattes to clip sections of your image, removing excess material in a single action. Finally, you'll investigate using the new Secondary Color Correction effect in the Three-Way Color Corrector to clean up and strengthen your green screen for better keying results.

To get things started, let me first give you some tips about the fundamentals for setting up a good-looking green screen shoot.