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Using Shrink, Blur, and Erode to Refine the Edges of the Key
In many cases, adjusting softness and tolerance is not enough to remove all the color spill from the edge of the front subject.
One way to change the color of the pixels around the edge is using color correction. For more information, see Removing Background Spill and Color Correcting Clips.
Another way to remove the unwanted color from the edge of the key is to make those pixels more transparent. To do this, use the Shrink, Erode, and Blur tools to modify the edge of the matte.
Use Shrink, Blur, and Erode to soften the matte and eliminate the noise that may appear in the edges when you play the keyed clip. Since the Keyer has sub-pixel matte controls, a small amount of blur and erode can produce very good results.
Note: The Shrink, Erode, and Blur tools are based on the filter type specified in the Setup controls. By default, a proportional Gaussian filter is used. See Setup Controls.
To access the Shrink, Blur, and Erode tools:Click the Matte button under the Key button in the Keyer Controls panel.
Note: You can access these same tools in the independent Matte Controls operator. To add this operator, choose Operators | Keying | Matte Controls.
Shrink
This tool removes pixels from the edge of the matte.
To shrink the edge of the matte:Enable Shrink and set the shrink width. A negative value expands the matte.
Pixels are removed from the edge of the matte. This has the effect of cutting away at the color spill around the edge of the subject.
Erode
This tool blends the light and dark edges of the matte. This is like feathering the contour of the matte. Like the Shrink tool, Erode can remove fine detail from the edge.
To erode the edge of the matte:Enable Erode and adjust the erode width.
The edge of the matte becomes softer. In the front clip, the blue spill is more transparent.
Blur
This tool applies a softening blur filter to the matte.
To blur the edge of the matte:
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