Posted by Richard Crowley on 10/02/05 19:53

"Rick Merrill" wrote ...
> So why would one want the key(hole) to be on one channel and the
> fill(background) on another?

So that you can independently manipulate them.

> How would this be used to put a 'bug' on screen?

As Mr. Kujbida already observed, the "key" (or "Alpha-channel")
is how we determine pixel-by-pixel how much of the background
imagse vs. the "bug" (or "insert") appear on the screen.

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