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Using Help | Contents
If lighting changes, you may need to adjust keying controls for other frames. Place
keyframes for the first set of keying properties at the start of the bluescreen scene. If you
are setting keyframes for one property only, use Linear interpolation. For footage that
requires keyframes for multiple interacting properties, use Hold interpolation (see "Hold
interpolation" on page 125).
If you set keyframes for keying properties, you may want to check the results frame by
frame. Intermediate keying values may appear, producing unexpected results.
Using a background color
To help you view transparency, temporarily change the background color of the compo-
sition, or include a background layer behind the layer you are keying out. As you apply the
key to the layer in the foreground, the composition background (or a background layer)
shows through, making it easy to view transparent areas.
Working with binary keys
The simplest type of key is the binary key, which creates pixels that are either transparent
or opaque. Pixels that match the specified key color are made transparent; those that don't
match remain opaque. Because binary keys do not create semitransparent pixels, they are
best for solid objects with sharp, defined edges, such as titles or credits, or for footage
items with a solid color background and no changes in background lighting.
Working with linear keys
Linear keys create a range of transparency across an image. A linear key compares each
pixel in the image to the key color you specified. If the color of a pixel closely matches the
key color, it becomes completely transparent. Pixels that don't match as well are made less
transparent, and pixels that don't match at all remain opaque. The range of transparency
values, therefore, forms a linear progression.
Working with matte tools
Once you have used a key to create transparency, use matte tools to remove traces of key
color and create clean edges. The Production Bundle includes the following matte tools:
Simple Choker, Matte Choker, Alpha Levels, and Spill Suppressor.
Using a garbage matte
A garbage matte is merely a portion of a bluescreen scene that contains only the subject
that you need. The remainder of the scene, which may contain undesired objects, is not
important and is masked out. The keyed subject can be placed in another scene for still
sequences or simple effects.
To create a garbage matte:
1 Use the Mask Tool to roughly outline a subject in bluescreen footage.
2 Apply one or more keys to mask out the remainder of the bluescreen scene.
3 Apply matte tools as necessary to fine-tune the matte.
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Applying Effects
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