Apple Shake 4 - Manual (Page 700)

700 Chapter 24 Keying
To correct a DV key (method two):
1 As in the first method, attach a ColorSpace node to the FileIn node containing the DV
footage, then set the outSpace parameter to YUV.
2 Next, attach a Reorder node to the output of the ColorSpace node. Set the channels
parameter to rrra to reassign the Y channel (the least compressed channel) to all three
channels.
The result will be a sharp grayscale image.
3 Attach a LumaKey node to the output of the Reorder node, and pull a key,
concentrating on the edges of the subject.
Don’t worry if there are holes in the middle of the image. You’re just trying to isolate as
much of the edge of the subject as possible.
4 Now, go back up to the FileIn node at the top of the tree, and branch off another
keying node, such as Keylight.
5 Pull a key, this time concentrating on the interior of the subjects.
In essence, this second key is a holdout matte that you can combine with the LumaKey
you created in step 3.