Adobe After Effects CS4 - Manual (Page 511)

505 USING AFTER EFFECTS CS4
Effects and animation presets
Last updated 12/21/2009
Other methods of animating paint strokes and text are also available. For example, you can animate text by using the
type tools and text animators, and you can animate a paint stroke applied with a paint tool. Paint strokes can have a
Write-on Duration setting, which you can use to create similar results as with the Write-on effect. You can also
animate shape paths for a similar result with the Trim Paths operation. (See “
Animating text ” on page 354, “ Animate
and edit paint strokes ” on page 304, and “ Shape attributes, paint operations, and path operations for shape layers ” on
page 333.)
Brush Position The position of the brush. Animate this property to create a stroke.
Stroke Length (secs) The duration, in seconds, of each brush mark. If this value is 0, the brush mark has unlimited
duration. Use a single, constant, nonzero value to create a snakelike movement of the stroke. Animate this value to
make the stroke expand
and contract.
Brush Spacing (secs) The time interval, in seconds, between brush marks. Smaller values produce smoother paint
strokes but take more time to render.
Paint Time Properties and Brush Time Properties Specifies whether paint properties and brush properties are applied
to each brush mark or to the entire stroke. Choose None to apply values at each time to all brush marks in the stroke.
Choose a property name for each brush mark to retain the value for that property at the time that the brush mark was
drawn. For example, if you choose Color, then each brush mark keeps the color specified by the Color value at the time
that the mark was drawn.
Paint Style How the paint stroke interacts with the original image:
• On Original Image Paint stroke appears over original image.
• On Transparent Paint stroke appears over transparency; the original image doesn’t appear.
• Reveal Original Image The original image is revealed by the paint stroke.
Keying effects
After Effects includes several built-in keying effects, as well as the Academy Award–winning Keylight effect, which
excels at professional-quality color keying. For information on the Keylight effect, see its documentation in the folder
in which the Keylight plug-in is installed. (See “
Plug-ins ” on page 641.)
Note: Though the color keying effects built into After Effects can be useful for some purposes, you should try keying with
Keylight before attempting to use these built-in keying effects. Some keying effects—such as the Color Key effect and the
Luma Key effect—have been superseded by more modern effects like Keylight.
For information about keying in general, including links to tutorials and other resources, see “ Keying introduction and
resources ” on page 383.
Color Difference Key effect
Note: Though the color keying effects built into After Effects can be useful for some purposes, you should try keying with
Keylight before attempting to use these built-in keying effects. Some keying effects have been superseded by more modern
effects like Keylight.
For information about keying in general, including links to tutorials and other resources, see “ Keying introduction and
resources ” on page 383.