Compositing Outside Keylight

When the foreground item within the green screen requires color adjustments or transformations, it's best to break the compositing out of the keying operations and use an Over node instead. To accomplish this, set the output to Unpremult (unpremultiplied). When selected, the key is knocked out of the foreground but then divided by its mask. This allows you to apply color corrections before compositing with an Over node.

Note

If you are applying only filters or transforms, you can set the output parameter to On Black.

1.	Set Output to Unpremult. When the output is switched to Unpremult, the composite looks nasty. Don't worry; it's only temporary, until you composite with an Over node. Next, use a Move2D node with an Over node to recomposite the background.
2.	Insert a Move2D node after Keylight1. The Move2D node is used for positioning the scarf.
3.	From the Layer tab, add an Over node after Move2D1 and connect Stabilize1 to the right input. Here's where the magic happens:
4.	In the Over1 parameters, activate preMultiply.

The unpremultiplied crap around the scarf is removed. Color correction and filtering nodes can now be placed between Keylight and Over1 without consequence.