Mask out objects with garbage mattes – Adobe Premiere Pro CS4 User Manual
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USING ADOBE PREMIERE PRO CS4
Compositing
Last updated 11/6/2011
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Mask out objects with garbage mattes
Sometimes the subject of a scene is properly keyed except for undesired objects. Use a garbage matte to mask out those
objects. Depending on the shape of the mask, you can use the Four-Point Garbage Matte, Eight-Point Garbage Matte,
or Sixteen-Point Garbage Matte. More points let you define more complex mask shapes.
The Garbage Matte keying effect provides settings that represent the x and y pixel coordinates of each point of the
garbage matte, measured from the top left corner of the frame. Changes appear in the Preview view of the Program
Monitor.
The microphone (left) is masked out by repositioning image handles in the Preview view of the Program Monitor (center), creating a garbage
matte that is then keyed and superimposed over a background (right).
1
In a Timeline panel, place the clip you want to superimpose in a track above the one containing the background clip.
2
In the Effects panel, click the triangle to expand the Video Effects bin and then click the triangle to expand the
Keying bin.
3
Drag either the Eight-Point Garbage Matte, the Four-Point Garbage Matte, or the Sixteen-Point Garbage Matte
effect to the superimposed clip.
Your choice of garbage matte depends on the number of points needed for mask shape.
4
In the Effect Controls panel, click the triangle next to the Garbage Matte name to expand the settings.
5
(Optional) If you’re animating the Garbage Matte Key over time, make sure that the current-time indicator is in
the position you want. Click the Toggle Animation icons for the position settings you plan to adjust.
6
Do any of the following to adjust the mask shape:
•
With the Garbage Matte effect selected in the Effect Controls panel, drag the Garbage Matte handles in the Program
Monitor.
•
Adjust the Garbage Matte point settings in the Effect Controls panel to specify the size and position of the garbage
matte.
7
(Optional) If you’re animating the Garbage Matte Key, move the current-time indicator either in the Effect
Controls panel or a Timeline panel and then change the Garbage Matte handle positions in the Program Monitor
or adjust the settings in the Effect Controls panel.
A new keyframe appears in the Effect Controls timeline when you move the handles in the Program monitor or change
the settings in the Effect Controls panel. You can also adjust the interpolation between keyframes by editing the
keyframe graph. Repeat this step as needed.
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