User Manual

Merge [MRG]
Merge Node Introduction
The Merge node combines two images based on the Alpha (opacity) channel associated with
the one in front. This node takes two inputs: a background and a foreground image. The
Operation mode determines which method is used to combine the foreground and background
images, supporting the standard Over, In, Held Out, Atop, and XOr methods for compositing
images. Meanwhile, an Apply Mode pop-up lets you use different composite modes, transfer
modes, or blend modes (whichever is your preferred terminology) to combine the foreground
against the background in different ways. This includes such standard modes as screen,
dissolve, multiply, overlay, as well as many others.
The Merge node can perform both additive (premultiplied) and subtractive (non-premultiplied)
compositing, depending on how your compositions and media are set up. However, you also
have the flexibility of using the Additive/Subtractive slider to blend between additive and
subtractive composite results, which has the bonus of providing solutions for problem edges in
some cases.
Ordinarily, the foreground and background input connections determine the layer order of
images composited with this node. However, you can also enable Z-Depth compositing if
Z-channels are available in the input images. Z-merging compares the depth value of each pixel
in each layer to determine which pixels should be in front and which should be behind.
Inputs
The Merge node provides three image inputs, all of which are optional:
–
Background: The orange background input is for the first of two images you want to
composite together. You should connect the background input before connecting
the foreground input. If you connect an image to the background without connecting
anything to the foreground input, the Merge node will output the background image.
–
Foreground: The green foreground input is for the second of two images you
want to composite together, which is typically a foreground subject that should
be in front of the background. If you connect an image to the foreground input
without connecting anything to the background input first, the Merge node won’t
output anything.
–
Effect Mask: (Optional) The effect mask input lets you mask a limited area of the
output image to be merged where the mask is white (where the foreground image
shows in front of the background), letting the background image show through by
itself where the mask is black.
Chapter – 86 Composite Nodes 1909