Inputs

Foreground
Background

These are the colors, structures or textures you want to layer or mix. Both color and alpha portions will be taken into consideration.

Blend Mode

This setting defines how Foreground and Background are mixed. Foreground will be used as the top layer that covers Background if Blend Mode is set to Normal.

Details about the mix or blend modes can be found here.

Alpha Handling

If the inputs used also have alpha components, their layering or blending can be controlled using this menu. The Alpha option has to be enabled in the Node’s Mask menu. Even if no Alpha channel exists, selecting One or Null can simulate a white or black alpha channel, respectively.

• Alpha Compositing: The Foreground’s and Background’s alpha channels are composited and together define the regions of the colors that will be blended.
•  Blend Mode: The Alpha channels will be treated exactly as the color components belonging to the Foreground and Background and are subjected to the same Blend Mode.
• Background/Foreground: Only the Alpha channel of the Background and Foreground will be returned.
• Null: Fills the output Alpha channel with zero
• One: Fills the output Alpha channel with one