ADOBE AFTER EFFECTS 7.0
User Guide
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Adjust the following controls for the Echo effect:
Echo Time (seconds) Specifies the time, in seconds, between echoes. Negative values seek backward in time; positive
values echo forward in time.
Number of Echoes Specifies the number of frames to combine for the Echo effect. For example, if two echoes are
specified, Echo makes a new image out of (current time), (current time + Echo Time), and (current time + 2 * Echo
Time).
Starting Intensity Specifies the intensity of the starting frame in the echo sequence. For example, if this is set to 1,
the first frame is combined at its full intensity. If this is set to 0.5, the first frame is combined at half intensity.
Decay Specifies the ratio of intensities of subsequent echoes. For example, if the decay is set to 0.5, the first echo will
be half the strength of the Starting Intensity. The second echo will then be half that, or 0.25 times the Starting
Intensity.
Echo Operator Specifies the operations to be performed between the echoes. Add combines the echoes by adding
their pixel values. If the starting intensity is too high, this mode can quickly overload and produce streaks of white.
Maximum combines the echoes by taking the maximum pixel value from all the echoes. Minimum combines the
echoes by taking the minimum pixel value from all the echoes. Screen emulates combining the echoes by
sandwiching them optically. This is similar to Add, but it will not overload as quickly. Composite in Back uses the
echoes’ alpha channels to composite them back to front. Composite in Front uses the echoes’ alpha channels to
composite them front to back. Blend averages the echoes together evenly.
To incorporate layer motion into the Echo effect
1
Set up your motion before applying the Echo effect.
2 Precompose the layer with any additional effects. This creates a new composition containing only that layer and
its motion keyframes.
3 Choose Effect > Time > Echo.
Note: Use a large Number of Echoes and a short Echo Time to get smooth streaking and smooth trail effects.
4 Set controls as needed.
To create an image trail using the Echo effect
1
Choose File > Import > File, select the source footage file, and then click OK.
2 Drag the source footage from the Project panel into the Composition panel.
3 Highlight the source footage layer in the Timeline panel, and create a motion path using position keyframes.
4 Highlight the source footage layer in the Timeline panel, and choose Layer > Pre-compose.
5 Type a name for the precomposed composition in the Pre-compose dialog box, select Move All Attributes into the
New Composition, and then click OK.
6 Select the name of the precomposed composition in the Timeline panel.
7 Choose Effect > Time > Echo.
8 Change the effect controls to these values:
• Echo Time: –0.10
• Number of Echoes: 10
• Starting intensity: 1.00
• Decay: 0.68
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