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CHAPTER 8 260
Superimposing and Compositing with Transparency
Compositing
Special effects for film or video are often created by shooting a scene against a color screen.
After the footage is digitized, the color screen is then made transparent with a key. The first
scene, or clip, is placed over a second clip, which usually includes some sort of background
scene. The result forms a composite, where the background is visible wherever the first clip
is transparent, making the first clip appear to belong with the background.
You often see such composites in feature films, where an actor appears to dangle from a
helicopter or appears to be floating in outer space. In this case, the actor is shot in an appro-
priate position against a color screen, and after making the color transparent, the actor’s scene
is composited onto the backdrop. Color screens are usually blue or green because these colors
are relatively absent from skin or hair color.
Fading
In addition to making portions of a clip transparent with keys, you can also adjust the opacity
of the entire clip to fade it in or out. You can use fading to create additional transitional effects
or to create simple superimposing.
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