Apple Shake 4 Tutorials - Manual (Page 171)

Chapter 5 Using Keylight 171
The Blur node is faster than using the RotoShape feathering.
11 In the Blur1 parameters, adjust the values of the xPixels and yPixels.
As soon as the blur is activated, the top of the head gets clipped off. What’s up with that?
The RotoShape node is 486 pixels high by default, while the other images are 540 pixels.
Be aware that Blur is the only function that let’s you work with the Infinite Workspace
on or off. By default, it is turned off so you can blur full-frame images without creating
a black edge on the border.
12 Click the spread button to toggle the Blur spread parameter to Outside Frame.
The Infinite Workspace is enabled and the clipping is removed.
Note: You can also adjust the RotoShape1 height parameter to 540 (in the Rotoshape1
parameters). As always, there are many ways to correct things in Shake.
spread = In Frame Only spread = Outside Frame