Keying is the process of making one element in an image—a shade of gray or a particular color—transparent, so that you can put one image on top of another image.
You began exploring this, though not using this name, when you were looking at titles in Chapter 11. The process of inserting text on top of another clip is one form of a key. However, this chapter focuses on the most popular types of keying: luma key and chroma key.
Keying is used every day in productions big and small. This chapter shows you how to use this technique successfully.
The reason keying became necessary is that many times, due to cost or physical impossibility, a script calls for putting an actor someplace where they can’t go—for instance, standing ...