Adobe 65021048 User Guide - Page 379

ADOBE PREMIERE PRO CS3 373 User Guide Cutoff Sets the opacity of nontransparent areas specified by the Threshold slider. Higher values increase transparency. You can also use the Luma Key to key out light areas by setting Threshold to a low value and Cutoff to a high value. See also "Luma Key effect" on page 337 Creating transparency and solid colors with mattes About mattes A matte is a clip (or any of its channels) that defines the transparent areas of that clip or another clip. White defines opaque areas, and black defines transparent areas. An alpha channel is often used as a matte, but you can use a matte other than the alpha channel. For information on using the mattes, see the topic for a specific matte key. Define transparent areas with Image Matte Key The Image Matte Key determines transparent areas based on a matte image's alpha channel or brightness values. To get the most predictable results, choose a grayscale image for your image matte, unless you want to alter colors in the clip. Any color in the image matte removes the same level of color from the clip you are keying. For example, white areas in the clip that correspond to red areas in the image matte appear blue-green (since white in an RGB image is composed of 100% red, 100% blue, and 100% green); because red also becomes transparent in the clip, only blue and green colors remain at their original values. Note: You can use the Titler to create shapes and text to use as mattes. A still image used as a matte (left) defines transparent areas in the superimposed clip (center), revealing background clip (right). 1 Add the clip (used as a background) to a video track in the Timeline panel. 2 Add the clip you want to superimpose to any track higher than the track containing the background clip. This is the clip revealed by the track matte. Be sure the superimposed clip overlaps the background clip in the Timeline panel. 3 In the Effects panel, click the triangle to expand the Video Effects bin and then click the triangle to expand the Keying bin. 4 Drag the Image Matte Key to the superimposed clip in the Timeline panel. 5 In the Timeline panel, select the superimposed clip. 6 In the Effect Controls panel, click the triangle to expand the Image Matte Key settings. 7 Click the Setup button , browse to the image being used as the matte, and then click Open to select the image. April 1, 2008