Intro to refining mattes in Motion

Keying is rarely a one-step process. Although adding a keying filter is the first step, additional work is often necessary to create a good key that retains detail around the edge of your subject. You can use the mask tools and alpha channel filters to turn a decent key into a great one:

• Create a garbage mask to crop unwanted background objects in the shot that can’t be keyed, such as the edge of a blue screen stage, lighting rigs, or tape that appears in the background.

• Create a holdout mask to restore part of a foreground image that has been removed by the key.

• Add a Matte Magic filter to refine matte edges.

• Add a Spill Suppression filter to manually neutralize a key color.

• Use multiple keys to isolate difficult-to-key regions in your foreground subject.