Matte Magic
The Matte Magic filter lets you manipulate the edges of a matte by shrinking, feathering,
and eroding them to improve difficult keys.
Parameters in the Inspector
Shrink:
Use this slider to manipulate the contrast of the matte in a way that renders
translucent regions of the keyed matte more translucent while shrinking the matte.
Feather:
Use this slider to blur the keyed matte, softening the edges by a uniform amount.
Erode:
Drag this slider to the right to gradually increase transparency from the edge of
the solid portion of the key inward.
Levels:
Use this grayscale gradient to alter the contrast of any matte or alpha channel,
by dragging three handles that set the black point, white point, and bias (distribution of
gray values between the black point and white point). Adjusting the contrast of a matte
can be useful for manipulating translucent areas of the key to make them more solid (by
lowering the white point) or more translucent (by raising the black point). Dragging the
Bias handle right erodes translucent regions of the key, while dragging the Bias handle
left makes translucent regions of the key more solid.
Black, White, Bias:
Click the disclosure triangle in the Levels row to reveal sliders for the
Black, White, and Bias parameters. These sliders, which mirror the settings of the Levels
handles described above, allow you to keyframe the three Levels parameters (via the Add
Keyframe button to the right of each slider). Keyframing the Black, White, and Bias
parameters may yield a better key, one that adapts to changing blue screen or green
screen conditions.
Mix:
Use this slider to set the percentage of the original image to be blended with the
filtered image. 100% is the filtered image, while 0% is the original, unfiltered image.
HUD Controls
The HUD contains the following controls: Shrink, Feather, and Erode.
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Chapter 13
Keying