Apple Final Cut Express 4 User Manual
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Part IX
 Mask Shape: Allows you to create an alpha channel in a clip that consists of a simple
shape—a diamond, oval, rectangle, or round rectangle. The solid part of the clip that
remains after applying the Mask Shape filter appears inside the shape that’s been
created. The vertical and horizontal scale of the shape can be altered, as can the
mask’s center. The Mask Shape filter can also be inverted to reveal areas of the clip
outside the shape.
 Soft Edges: Allows you to feather the edges of a clip. You can extend the softening of
the left, right, top, and bottom edges of the clip into the clip by different amounts.
The feathering appears as a gradient that always extends to the edge of the clip. The
Soft Edges filter overrides all other alpha channel information created by any other
filters appearing before it.
Example: Using the Image Mask and Mask Feather Filters
In the following example, a still image is used to create an alpha channel in another clip.
1
Open the clip to be masked in the Viewer.
2
Choose Effects > Video Filters > Matte > Image Mask.
3
Click the Filters tab in the Viewer.
4
Drag the Border.tif clip to the Mask clip well of the Image Mask filter.
This example uses a
grayscale TIFF file, called
Border.tif, that has a
white center surrounded
by a rough black border.
Drag the clip to the
clip well.