Before we get into detail about specific keying methods and when to use them, here is some top-level advice to remember when creating a matte:
Figures 6.1a, b, and c. The choice of background influences what you see. Against the default black, almost no detail is visible (a). With the checkerboard turned on, you can begin to see shadows (b). Flaws in the matte become clearest with a bright, solid, contrasting background (c). (Source footage courtesy Pixel Corps.)
Figure 6.2. The keyed layer can be soloed at any time, revealing it against the background of your choice.
Figure 6.3. A coyote ugly, chewy matte is typically the result of clamping the foreground or background (or both) too far.
Figure 6.4. A glimpse of the alpha channel can reveal even more problems, such as faint holes in the foreground, which should be solid white. This is the matte from Figure 6.1.
Keep these basics in mind as you reveal the various keying options. You are also encouraged to review this list when it comes time to apply a key to your own shot, especially if you're new to keying.
Linear Keyers and Hi Con Mattes
Section I. Working Foundations
The 7.0 Workflow
Selections: The Key to Compositing
Optimizing Your Projects
Section II. Effects Compositing Essentials
Rotoscoping and Paint
Effective Motion Tracking
Film, HDR, and 32 Bit Compositing
Section III. Creative Explorations
Working with Light
Climate: Air, Water, Smoke, Clouds
Pyrotechnics: Fire, Explosions, Energy Phenomena
Learning to See