User Manual

2 You’ll want to use Node 1 to color correct the image to optimize it for keying. In
this example, the foreground plate is log-encoded, so a LUT is added to Node 1 to
normalize it.
3 Add a Serial node after Node 1 and connect its key output to the Alpha Output. This is a
fast way to build this composite if you’re confident that the corrections you’ve made in
Node 1 won’t adversely affect the key (or if you know they’ll improve it by expanding the
contrast of a flat-contrast source clip).
Alternately, you could create a second processing branch by adding a disconnected
node (Node 2), connecting the Source node to its RGB input, and then connecting its
key output to the Alpha Output you just added. Creating a second image processing
branch from which to pull your key lets you key directly from the source (assuming the
source is fit to key without adjustment), avoiding any problems that grading the first
node could introduce to the key.
Node 1 grades the clip, expanding contrast to improve both the image,
and its ability to be keyed. Node 2 uses Qualifier controls to pull the key.
4 Use the Qualifier controls of Node 2 to key out the green background, and then turn on
the Invert checkbox to create the proper composite. In this example, we’re using the 3D
Qualifier mode to pull a high-quality key.
An HSL Qualification to key the green feeding the
Alpha Output to create transparency
Chapter – 127 Channel Splitting and Image Compositing 2887