Using Masks to Aid Keying Effects
Keying is rarely a one-step process. Although adding a keying filter is the first step, there
is usually additional work that must be done to create a good key that retains detail
around the edge of your subject. You can use the mask tools and alpha channel filters
presented in this section to turn a decent key into a great one. For more information
about using Motion’s keying filters see
When using masks with keying, apply any masks after applying the keyer.
Using Shapes, Masks, and Paint Strokes