Expert: Joseph Silver - 11/6/2006

Question
sir, may I know about Mattes in After Effect ? what is matts (travelling matte, alpha matte, etc.). What's the basics fundamentals behind it ? How it works ?

Answer
Mattes are used to reveal or hide. They are used in many different ways; one common use of mattes is to hide a flaw that was shot in-camera. For example, say you are shooting a person against blue-screen and there is a boom in -frame that you want to take out - in this case, you will use a matte or traveling mattes to hide the boom (a "traveling" matte is a matte in motion, created by the use of keyframes). Another common use of mattes is to separate a person from the background he is shot against. For example, say you shot your person in one scenario but you wanted to put them in another - then, you might (tediously) cut mattes around them, creating an "alpha matte" which you could then use to help you composite the person into another scene.

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