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605Final Cut Pro User Guide
• Black, White, Bias: Click the Levels disclosure triangle to reveal sliders for the Black,
White, and Bias parameters. These sliders, which mirror the settings of the Levels
handles described above, allow you to keyframe the three Levels parameters (using
the Add Keyframe button to the right of each slider). Keyframing the Black, White,
and Bias parameters may yield a better key, one that adapts to changing blue-screen
or green-screen conditions.
• Shrink/Expand: Use this slider to manipulate the contrast of the matte to affect
matte translucence and matte size simultaneously. Drag the slider left to make
translucent regions more translucent while simultaneously shrinking the matte.
Drag the slider right to make translucent regions more solid while simultaneously
expanding the matte.
• Soften: Use this slider to blur the keyed matte, feathering the edges by a uniform
amount.
• Erode: Drag this slider right to gradually increase transparency from the edge of the
solid portion of the key inward.
4. Click Light Wrap to reveal the following controls:
• Amount: Use this slider to control the overall light wrap effect, setting how far into
the foreground the light wrap extends.
• Intensity: Use this slider to adjust gamma levels to lighten or darken the interaction
of wrapped edge values with the keyed foreground subject.
• Opacity: Use this slider to fade the light wrap effect up or down.
• Mode: Use this pop-up menu to choose the compositing method that blends the
sampled background values with the edges of the keyed subject. There are five
modes:
• Normal: Evenly blends light and dark values from the background layer with the
edges of the keyed foreground layer.
• Lighten: Compares overlapping pixels from the foreground and background
layers, and then preserves the lighter of the two. This method is good for creating
a selective light wrap effect.
• Screen: Superimposes lighter portions of the background layer over wrapped
areas of the keyed foreground layer. This method is good for creating an
aggressive light wrap effect.
• Overlay: Combines the background layer with the wrapped areas of the keyed
foreground layer so that overlapping dark portions become darker, light portions
become lighter, and colors become intensified.
• Hard Light: Similar to the Overlay composite mode, except that colors become
muted.