Apple Final Cut Pro 5 - Manual (Page 1189)

402 Part II Project Interchange
9 If you still see light fringing at this point, or if you were forced to use settings so
extreme in the Chroma Keyer that some of your foreground subject was eaten away
around the edges, you can apply the Matte Choker filter. After you apply the Matte
Choker filter, adjust the Edge Thin and Edge Feather sliders. This is the point where you
should work to eliminate all the background fringing.
Moving the Edge Thin slider to the right further shrinks the alpha channel around the
foreground subject, eliminating still more fringing. Moving the Edge Thin slider to the left
expands the alpha channel, allowing you to replace areas of the foreground subject that
were lost. The Edge Feather slider allows you to blur the edges even further, if necessary.
10 If you’re satisfied with your key, but there is some color from the background that is
spilling onto the edges of your foreground subject, you can go back to the Chroma
Keyer tab in the Viewer and adjust the Enhance slider to desaturate this spill so that it’s
not noticeable. Don’t move the Enhance slider too far, or you may get undesirable
coloration in the edge of your subject.
11 If there’s still more colored spill on your foreground subject that the Enhance slider
didn’t eliminate, you can apply the Spill Suppressor filter.
The Spill Suppressor filter desaturates color spill that may appear anywhere on the
foreground subject, not just on the edges. For example, a little of the background color
may show through translucent areas of the foreground subject, such as wispy hair or
sheer clothing. Once you’ve applied the Spill Suppressor filter on your keyed clip, adjust
the Amount slider to determine how much to desaturate the spill color in the
foreground image.
12 To eliminate any unwanted elements that didn’t get keyed out, such as rigging and
lights around your subject, or the edge of the blue or green screen itself, use the Crop
parameter in the Motion Settings tab of the foreground clip to cut those elements out
of the picture. If the area you need to crop is irregular, you can apply a Garbage Matte
filter, instead.
The image is cropped
on both sides to remove
extraneous elements.