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Lesson 4. Color and Opacity > Applying the Chroma key

Applying the Chroma key

The Chroma key lets you select any color as the transparent area. If you can't videotape footage using a blue or green background because of conflicting colors in your clip (such as the color of someone's clothes), you can use any solid color background and then use the Premiere Pro Chroma key to make that color represent your transparent area.

Now, you'll use the Chroma key on a clip with a range of grey in its background.

Make the Sequence 01 Timeline active, by double-clicking Sequence 01 in the Project window or by clicking on the Sequence 01 tab in the Timeline.

Choose Edit > Select All.

Choose Edit > Clear.

From Bin 01 of the Project window, insert Notmuch.avi at the beginning of the Sequence 01 Timeline.

In the Project window, double-click Mtntop.avi so that it appears in the Source view of the Monitor window.

In an Earlier lesson, you trimmed the In point of Mtntop.avi to 00;00;05;00 and its Out point to 00;00;08;12. The duration of Notmuch.avi is 00;00;03;06. In the Source view for this exercise, set the In point marker to 00;00;05;07 and the Out point to 00;00;08;12 so that the duration of Mtntop.avi is equal to the duration of Notmuch.avi.

Click on the Toggle Take Audio and Video button () and make sure it is set to Take Audio and Video.

Drag Mtntop.avi from the Project window to the Video 2 track, aligning its In point with the beginning of the Timeline.

Scrub through the Timeline to preview the movie before applying the Chroma Key effect.

Go to the Effects palette and type chroma in the Contains area. The Chroma Key effect appears.

Select the Chroma Key effect and drag it to Mtntop.avi in the Video 2 track of the Timeline window.

Click on the Mtntop.avi clip in the Timeline window and then go to the Effect Controls window.

Click on the triangle next to the Chroma Key effect to view the settings.

Notice that the Color box in the Chroma Key Settings area now displays white. You can click the white box to either select a color or assign a key color from the Color Picker. For this exercise, you'll assign the blue sky color from the last frame.

Click on the Color box in the Chroma Key effect.

The Color picker opens. Premiere Pro allows you to assign color in five different ways.

In this exercise, type 168 for the Red (R) value; 190 for the Green (G) value, and 204 for the Blue (B) value and click OK.

The cloudy background in Mtntop.avi is dithered (not a solid color). You'll need to use the Blend settings to make this clip's background transparent. The Blend settings blend the edges of the image with the background by gradually changing the opacity where the color pixels meet.

In the Effect Controls window, click in the box next to the Blend area and type 40. Notice how the edges between the image and background lose their sharpness.


Another way to adjust the Blend settings is to use the Blend slider. Click the triangle next to the Blend area to reveal the slider. Drag the slider to 40.

The Threshold and Cutoff settings do not apply to this clip; however, it is good idea to clean up the edges and the blending by using the Smoothing controls.

Click on the menu triangle to the right of the Smoothing area and select High.

Preview the clips using Real-Time preview or by scrubbing through the Timeline. Notice how the Mtntop.avi clip now appears on-screen with no clouds in the sky.

Save the project.

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