Apple Final Cut Pro 7 - Manual (Page 1235)

Clicking this button and then Shift-clicking with the eyedropper in the Viewer or Canvas
allows you to select another region of the background screen that wasn’t keyed out
by your first use of this control. This broadens the range of colors to be keyed out and
enlarges the keyed-out area. You can do this repeatedly to broaden the range of
keyed-out color to include shadows or highlights on the background screen, if necessary.
• View Final/Matte/Source button (the key): This button has three states: Final, Matte, and
Source.
• Final: The default state (a key against a gray background) lets you see the end result,
the effect happening within the keyed area.
• Matte: The second state (a black key against a white background) displays the key
itself as a grayscale image, so you can fine-tune the key without being distracted by
the image.
• Source: The third state (a key against a blue background) shows only the original
video image.
Important: Before you render or output video using the Chroma Keyer filter, make sure
that the View Final/Matte/Source button is in the Final state.
• Invert Selection button: Click this button to invert the key you’ve defined. For example,
if you’ve set up a key based on the color of a green car and used a grayscale copy of
the clip in the background so that the car is grayscale and the background is color,
clicking the Invert Selection button reverses the key so that you see the car in color
and the background appears in grayscale.
Three sliders at the bottom
of the Chroma Keyer let you
make further adjustments.
• Edge Thin slider: Drag this slider to make the size of the currently defined key larger or
smaller. This can help you remove unwanted edging around your subject.
• Softening slider: Use this slider to blur the edges of your key to make it blend better
with the background image. This can come in handy to soften the jagged edges that
sometimes develop when chroma keying material captured with the DV codec.
• Enhance slider: Adjust this slider to selectively eliminate any spill of the key color that
may be visible in the semitranslucent areas of your key, such as edges and holes.
Example: Using the Chroma Keyer Filter
The following example illustrates a typical use of the Chroma Keyer filter.
To apply the Chroma Keyer Filter
1 Edit the green-screen clip you want to key into the Timeline.
If you wish, you can use a superimpose edit to place the green-screen clip over a clip you
want to use as the background.
1235 Chapter 72 Keying, Mattes, and Masks