Apple Shake 4 - Manual (Page 187)

Chapter 5 Compatible File Formats and Image Resolutions 187
Parameters
This node displays the following controls in the Parameters tab:
cropLeft
The number of pixels to crop from the left of the image. This parameter defaults to 0,
the leftmost pixel of the image.
cropBottom
The number of pixels to crop from the bottom of the image. This parameter defaults to
0, the bottommost pixel of the image.
cropRight
The number of pixels to crop from the right of the image. This parameter defaults to
the width expression.
cropTop
The number of pixels to crop from the top of the image. This parameter defaults to the
height expression.
Viewport
The Viewport node is exactly like the Crop node, but it keeps the image information
outside of the frame so you can perform later transformations.