Apple Shake 4 - Manual (Page 468)

468 Chapter 16 Compositing With Layer Nodes
matteMult
Premultiplies the output image by multiplying the first input image by the alpha
channel of the second input image.
• 0 = not premultiplied
• 1 = premultiplied
invertMatte
Inverts the result matte.
• 0 = do not invert the matte
• 1 = invert the matte
Under
The Under node is the same as the Over operation, except that it reverses the two input
images. This is largely trivial for the script and the interface, but is extremely handy
when working in command-line mode, since you can easily work on a background
image.
Parameters
This node displays the following controls in the Parameters tab:
clipMode
Toggles between the foreground (0) or the background (1) image to set the output
resolution.
preMultiply
When this parameter is on (1), the foreground image is multiplied by its alpha mask. If
it is off (0), it is assumed that the foreground image is already premultiplied.
addMattes
When enabled (1), the mattes are added together for the composite.
Xor
The Xor node is somewhat like a combination of the Inside and Outside nodes. It is used
to remove overlapping mask areas.
Parameters
This node displays the following controls in the Parameters tab:
clipMode
Toggles between the foreground (0) or the background (1) image to set the output
resolution.
useMatte
Normally, the calculation performed by this node is based on comparing the RGB
values in the foreground image to the RGB values in the background image. Turning
useMatte on instead compares the alpha channels of the input images, but this effect
also appears in the RGB channels.