footage (before the moving object enters the scene). For this reason, the Difference Matte
key is best used for scenes that have been shot with a stationary camera.
To replace a static background behind a moving object:
1
Find a frame of your clip that consists only of the static background.
2
Save this frame as an image file. (For information about saving a frame, see “Exporting a
still image” on page 300.)
3
Place the video clip in a track.
4
In the Effects window, expand the Video Effects bin and then the Keying bin.
5
Drag the Difference Matte effect to the video clip.
6
Click Setup to select the frame you saved.
7
Select the Reverse Key option to key out the static background.
8
Adjust options as needed.
Setup
Click to select an image to use as the difference matte.
Similarity
Broadens or reduces the range of color that will be made transparent. Higher
values increase the range.
Smoothing
Specifies the amount of anti-aliasing (softening) that Adobe Premiere Pro
applies to the boundary between transparent and opaque regions. Choose None to
produce sharp edges, with no anti-aliasing. This option is useful when you want to
preserve sharp lines, such as those in titles. Choose Low or High to produce different
amounts of smoothing.
Reverse
Inverts the values of the matte.
Drop Shadow
Adds a 50% gray, 50% opaque shadow offset from the opaque areas of the
original clip image by four pixels down and to the right. This option works best with
simple graphics such as titles.
Mask Only
Displays only the clip’s alpha channel, as modified by the key settings.
Using the Track Matte key
Use the Track Matte key to show one clip through another, using a third file as a matte that
creates transparent areas in the superimposed clip. This effect requires two clips and a
matte, each placed on its own track. You may want to set aside an entire track for the
matte, because you must hide that track. White areas in the matte are opaque in the
superimposed clip, preventing underlying clips from showing through. Black areas in the
matte are transparent, and gray areas are partially transparent.
Using Help | Contents | Index Back 232
Adobe Premiere Pro Help Superimposing and Compositing
Using Help | Contents | Index Back 232
A matte containing motion is called a
traveling matte
or
moving matte
. The matte may
consist of motion footage, such as a blue-screen silhouette, or you can animate a still
image matte by applying the Motion effect in Adobe Premiere Pro (see “Animating effects
by using keyframes” on page 245 and “Animating effects in the Timeline window” on
page 224). If you animate a still image, consider making the matte frame size larger than
the project frame size so that the edges of the matte don’t come into view when you
animate the matte.
Because the Track Matte key can be applied to a video clip, the matte can change over time.
You can create mattes in various ways:
•
Use the Title window to create text or shapes (grayscale only), save the title, and then
import the file as your matte.
•
Create a matte from any clip using the Chroma, RGB Difference, Difference Matte, Blue
Screen, Green Screen, or Non Red key. Then select the Mask Only option.
•
Use Adobe Illustrator or Adobe Photoshop to create a grayscale image and import it
into Adobe Premiere Pro.
To apply the Track Matte key:
