This is the main compositing operation. The Over operator takes an image (combined with a matte) and lays it on top of the second image. Intuitively, people understand compositing with a matte channel as if the matte were a cookie-cutter which removes all excess information from the foreground image and the result is then pasted on top of the background.
We assume the foreground image already having a built-in matte channel and the foreground's color channels have already been pre-multiplied by that matte channel.
Name | Description |
---|---|
name | Object name [string] |
input_a | "A" input bitmap [bitmap] |
input_b | "B" Input bitmap [bitmap] |
output | Output bitmap [bitmap] |