If you've tried out Premiere's new Title Designer tool, used the Motion Settings dialog box, or worked on video effects that use alpha channels, you have already composited?that is, layered graphics or video clips over other images.
Compositing can add immeasurably to your video projects. Sometimes the impact is obvious?sliding videos in boxes onto the screen sends a clear message that you have done something out of the ordinary with your production. Other times it's subtle. We don't think twice when we see a TV weatherperson gesturing at a map or graphics. As shown in Figure 14.1, in fact that TV personality is standing in front of a green or blue wall and watching some monitors to see what he or she is pointing at.
Every computer game with live actors and many movies use compositing. "Green screen" studios let game developers place actors in science fiction settings created with 3D computer graphics. Such sets let actors work in relative safety while the finished product has them dangling from a skyscraper, hundreds of feet in the air.
For most budding professional video producers, such high-budget studio access may be out of the question. But you can add some nice composited special effects to your projects simply with a few tweaks of Premiere's tools.