Id matte effect, Audio effects, Backwards effect – Adobe After Effects CS3 User Manual
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AFTER EFFECTS CS3
User Guide
371
See also
ID Matte effect
Many 3D programs tag each element in a scene with a unique Object ID. The ID Matte effect uses this information
to create a matte that excludes everything in the scene except the element you want.
Original (top left), with ID Matte applied using the near alien as the ID Selection (bottom left), and composited over a new background (bottom
right)
Aux. Channel
Isolate elements based on Object ID or Material ID.
ID Selection
The ID value for an object.
To determine the ID of an object, select the ID type from the Aux. Channel menu in the Effect Controls panel, and
click the object in the Composition panel or Layer panel using the Selection tool while the effect is selected. If Object
ID is selected for Aux. Channel, ID Selection automatically updates to the Object ID for the object you click.
Feather
The amount of feather along the matte’s edges.
Invert
Inverts the selection. Select to matte out the object specified by ID Selection. Deselect to matte out everything
but the object (default).
Use Coverage
Creates a cleaner matte by removing the colors stored behind the object from the pixels along the edge
of the matte. This option works only if the 3D image contains a coverage channel that stores information about the
colors behind objects.
See also
Audio effects
Backwards effect
The Backwards effect reverses a layer’s audio by playing it from the last frame to the first frame. The frames remain
in their original order in the Timeline panel. Select Swap Channels to swap left and right channels.