Work with planes

To...	Do this
Copy image data from one image into a plane of another image	Create a Channel Copy node. Connect the compositing node (usually a [File node\|Node:cop2/file]) containing the color image to the first input, and the compositing node containing the deep raster plane to the second input. In the Channel Copy node’s parameters, set Source to "Input 2" and set Target to the name of the deep raster plane you're importing.
Create planes from scratch	Add a generator node and on its Image tab set the Add plane parameter.
Use one image as the alpha channel of another image	The Switch Alpha COP moves the alpha plane from its second input into its first input.
Use color data as the basis for the alpha channel	See keying .

Tip

You can also use the Channel Copy operator to swap image data between planes/components or inputs.

Compositing