The Blend Matte tool lets you mix two images using a matte image to define the areas of visibility between the front and back images.

To blend two images using a matte:

1. Drag a Blend Matte tool from the Composition folder in the Tools tab to the dependency graph in the Schematic view.
2. Connect the front, back and matte images to the tool.
3. Select the Blend Matte Channel: Alpha, Red, Green, Blue, or Luma, as appropriate for the image you are using as the matte. The default choice is Alpha.

   Select Invert if you want to invert the result.

   

4. Select the tool output: Composite, Front, or Front and Matte.