Apple Shake 4 - Manual (Page 883)

Chapter 28 Filters 883
controlChannel
The channel of the controlling image to use to control the amount of the effect.
invert
Inverts the controlChannel.
IRBlur
The IRBlur node is an image-based version of the RBlur node, using the alpha mask of a
second image (by default) to control the amount of radial blurring on an image. This is
useful for faking motion blur effects.
In this example, the foreground objects (cubes) are rendered on a beach in a 3D
software package with the depth information. The 3D image is composited over a
background photo of the beach. The DepthKey node was used to extract a matte of the
depth supplied by the 3D render. The matte is then fed into the second image of the
IRBlur to give a zooming effect.
Parameters
This node displays the following controls in the Parameters tab:
xCenter, yCenter
The center point of the blur. By default, these parameters are set to width/2, height/2.
iRadius
The distance from the center that contains the blur sample area.
oRadius
The outer edge for the blur area.
aspectRatio
This parameter inherits the current value of the defaultAspect global parameter. If
you’re working on a nonsquare pixel or anamorphic image, it is important that this
value is set correctly to avoid unwanted distortion in the image.
damp
A gamma value on the blur.
amplitude
The overall amount of blur. This number can also be negative, to blur away from the
viewer, rather than toward the viewer.