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Id matte effect – Adobe After Effects CS4 User Manual

Page 441

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435

USING AFTER EFFECTS CS4

Effects and animation presets

Last updated 12/21/2009

More Help topics

About 3D Channel effects

” on page 430

Preparing and importing 3D image files

” on page 98

3D layers

” on page 179

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.

This effect works with 8-bpc, 16-bpc, and 32-bpc color.

Original (upper-left), with ID Matte applied using the near alien as the ID Selection (lower-left), and composited over a new background (lower-
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 edges of the matte.

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.

More Help topics

About 3D Channel effects

” on page 430

Preparing and importing 3D image files

” on page 98

3D layers

” on page 179

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