Left Toolbar > Compose Nodes > Blend
The Blend node blends two images, background and foreground, into a single output image, using a blend function, and a mask input image.
On the left toolbar choose Compose Nodes > Blend. >
Drag the Blend icon into the Node Graph.
Connect the first input image to the Bg input socket.
Connect the second input image into the Fg input socket.
Connect the third input image into the Mask input socket.
Set the attributes to control the Blend output.
The background image.
The foreground image.
The mask image.
The composed Image.
Sets the blending mode:
The opacity of the foreground image in the blend process.
If a background image is not connected to the node, this color is used as background.
If a foreground image is not connected to the node, this color is used as foreground.