2011

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white regions, or both. You can specify what range of values is black and what
range is white. In addition, you can control the maximum number of pixels
of edges to preserve and the softness controlling the blend between the
preserved edge region and the interior filled-in region. The specified edge
preservation width is considered to be a maximum limit; for instance, when
removing holes in white regions, all pixels that are connected to black regions
and within the specified distance from black regions will be considered part
of the edge and preserved. Essentially the black region fills into the edges until
it hits the white region or its maximum width limit, and then this is used as
a mask to preserve input values in the filled region.
The Cleanup Alpha tool has the following parameters:
To:Use:
Enable the black or white (or both) clean up controls.Enable
Control the number of pixels of edges to preserve.Edge Width
Control the blend between the preserved edge region and
the interior filled-in region.
Edge Softness
Specify black or white (or both) thresholds.White/Black Threshold
Gesturally manipulate the alpha remapping.Curve
Reset the remapping curve.Reset
Comp Alpha Tool
The Comp Alpha tool lets you composite two mattes together. It has front
and back inputs, and works by extracting a matte from the front image and
compositing it over the alpha channel of the back input using a choice of
compositing operators. The back is the primary input and the output inherits
the format of the back input.
350 | Chapter 16 2D Compositing