Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 534

Echo effect
The time, in seconds, between echoes. Negative values create echoes from previous frames;
Echo Time (seconds)
positive values create echoes from upcoming frames.
The number of echoes. For example, if the value is 2, the result is a combination of three frames:
Number of Echoes
the current time, the current time + Echo Time, and the current time + (2 * Echo Time).
The opacity of the first image in the echo sequence.
Starting Intensity
The ratio of the opacity of an echo to the opacity of the echo preceding it in the echo sequence. For example,
Decay
if Decay is 0.5, then the opacity of the first echo is half of the Starting Intensity; the second echo is half of that, or one
quarter of the Starting Intensity.
The blending operation used to combine the echoes.
Echo Operator
• Combines the echoes by adding their pixel values. If the starting intensity is too high, this mode can quickly
Add
overload and produce streaks of white.
•
Combines the echoes by taking the maximum pixel values from all of the echoes.
Maximum
• Combines the echoes by taking the minimum pixel values from all of the echoes.
Minimum
• Emulates combining the echoes by sandwiching them optically. This mode is similar to Add, but it won't
Screen
overload as quickly.
• Uses the echoes' alpha channels to composite them back to front.
Composite In Back
• Uses the echoes' alpha channels to composite them front to back.
Composite In Front
• Averages the echoes.
Blend
See also
"Precompose layers" on page 118
Posterize Time effect
The Posterize Time effect locks a layer to a specific frame rate. It's useful on its own as a special effect, but it also has
more subtle uses. For example, 60-field-per-second video footage can be locked to 24 frames per second (and then
field rendered at 60 fields per second) to give a filmlike look. Also, nested compositions can be locked to a given
frame rate. This effect is sometimes called Strobe in hardware devices.
Note: A layer's masks and any previously applied effects are ignored by the Posterize Time effect. To posterize the time
of a layer with its masks and effects, precompose the layer before applying the Posterize Time effect.
Animating the value of the Frame Rate slider can give unpredictable results. For this reason, the only interpolation
method allowed for the frame rate is Hold.
This effect works with 8-bpc and 16-bpc color.
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