Apple Final Cut Pro 7 - Manual (Page 1223)

This chapter covers the following:
• Ways to Layer and Isolate Elements in Clips (p. 1223)
• Using Keying to Isolate Foreground Elements (p. 1226)
• Overview of Compositing Using the Chroma Keyer Filter (p. 1228)
• Working with the Chroma Keyer Filter (p. 1231)
• Using Mattes to Add or Modify Alpha Channels (p. 1242)
• Using Masks to Replace or Modify Alpha Channels (p. 1245)
You can isolate specific elements of clips from the background and combine those
elements with other clips by using keying, mattes, and masks.
Ways to Layer and Isolate Elements in Clips
People have been layering visual elements together since the dawn of the movie industry.
Although digital techniques have increased the potential number of layers from two or
three to two or three thousand (and even more), the same basic principles are used. The
names vary from one industry to the next, but as film and video merge on a single digital
horizon, the terms are becoming more interchangeable.
What Are Mattes and How Can You Use Them?
Matte, or hold matte, originated with film and photography. It traditionally refers to any
opaque material that, when held in front of a camera lens, prevents certain areas of the
film from being exposed during shooting. Then, the camera can be rewound, and a matte
of the reverse shape can be used to prevent exposure on the already exposed part of the
film while the other portion is exposed. The result is two different images shot at different
times combined together in one frame.
The same principle can be used in digital applications. In the case of cameras, the mattes
are handmade, physical objects, but on a computer they can be drawn and applied
digitally.
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Keying, Mattes, and Masks 72