Apple Final Cut Express HD - Manual (Page 825)

Chapter 55 Keying, Mattes, and Masks 825
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 Apply the Image Mask filter to the clip being keyed, by opening this clip into the
Viewer, then clicking the Filters tab.
2 Drag the Border.tif clip to the clip control of the Image Mask filter.
In this example, a grayscale TIF
file, called “Border.tif,” that has a
white center surrounded by a
rough black border, is used.
Drag the clip to the
clip control in this filter.