Apple Final Cut Pro 5 - Manual (Page 1179)

392 Part II Project Interchange
A second Matte Choker filter can also be applied to fill holes in the foreground subject that
appear as a result of aggressive settings applied to key out the background. By adjusting
the Edge Thin slider to the right, you can fill in semitranslucent areas in your foreground
subject, without changing the background areas you’ve already keyed out. For more
information about the Matte Choker filter controls, see “
Matte Filters ” on page 210.
Step 4: Readjust the Chroma Keyer filter’s settings
When keying, additional filters you add usually affect the overall results of previously
applied filters, so after applying the Matte Choker, you’ll probably want to readjust the
Chroma Keyer filter’s settings to take into account the effect the Matte Choker is
having. Changes you make to the Chroma Keyer filter’s settings affect what the Matte
Choker does, so go back and forth between the Chroma Keyer and Matte Choker filters
until you find a balance of settings that effectively removes the background without
eating into your foreground subject.
Step 5: Desaturate the key with spill suppressor filters
If you have some slight color spill from the background around the edge of your
foreground subject, you can use the Enhance control of the Chroma Keyer to
desaturate the color spill so that it’s not noticeable.
If you have other regions of color spill that appear within your foreground subject—
showing through a sheer dress, for instance—you may want to use the Spill Suppressor
- Blue or Spill Suppressor - Green filter to selectively desaturate just the key color so
that it’s not noticeable. The spill suppressor filters may affect the overall color of the
foreground subject, however, so you may need to use a color correction filter to
compensate for this effect.
Step 6: Crop out elements using the Garbage Matte filter
If there are “unkeyable elements” other than your foreground subject that you want to
eliminate from the frame, such as props, lighting fixtures, or other undesirable objects,
you can use one of the Garbage Matte filters to remove those elements. For more
information on using Garbage Matte filters, see “
Using Mattes to Add or Modify Alpha
Channels ” on page 404.
Step 7: Color correct the foreground and background clips to match
Even if you shot your background and foreground clips to match one another, it’s
unlikely the lighting you used matches perfectly. For this reason, it’s usually necessary
to color correct either the foreground subject or the background to make sure the two
match. For more information on color correction in Final Cut Pro, see Chapter 20, “
Color
Correcting Clips ,” on page 411.
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Tip: When shooting video you intend to composite together using keying filters, it’s
important to make sure that the direction of the lighting matches in both the
foreground and background shots. You can color correct for color temperature, relative
brightness levels, and contrast, but lighting direction cannot be altered.