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Creating video masks

You can also use video files to create masks, although the process can be more complicated than using an image as a mask. The key to any mask is contrast. You can increase the difference between the light and dark areas of a video file using video effects plug-ins.

1.Insert the video that you want to use as a mask into a video track.

2.Drag a Black and White plug-in from the Video FX window to the event to remove the color. For more information, see Adding a video effects plug-inon page 242.

3.Drag a Brightness and Contrast plug-in from the Video FX window to the event.

4.Adjust the Brightness and Contrast to create the mask. Watch the Video Preview window for a real- time preview of the mask. Adjust the effect so that parts of the video are completely black (opaque) and other parts are completely white (transparent). This can often mean increasing the contrast while decreasing the brightness.

5.If necessary, mask areas can be inverted (reversing the black and white areas) with an Invert plug-in

or by selecting the Invert check box in the Mask Generator window. For more information, see Using the Mask Generator on page 263.

Original color event

Black and White

Brightness and Contrast Invert plug-in

 

plug-in

plug-in

After you have created the mask, place it in the highest track. Add another video event to another track below the mask and click the Make Compositing Child button () on that track. Any video that appears in a lower track below the Parent mask track and its Child shows through the areas outside of the mask. The entire setup is pictured in the following illustration.

Mask track (Parent)

Masked video (Child)

Background

CHP. 14

USING VIDEO FX, COMPOSITING, AND MASKS