Adobe Premiere Pro CS3 - Manual (Page 371)

ADOBE PREMIERE PRO CS3
User Guide
365
• If a clip’s source file doesn’t contain an alpha channel, you must manually apply transparency to individual clip
instances where you want transparency. You can apply transparency to a video clip in a sequence by adjusting
clip opacity or by applying effects.
• Applications such as Adobe After Effects, Adobe Photoshop, and Adobe Illustrator can save clips with their
original alpha channels, or add alpha channels, when the file is saved to a format that supports an alpha channel.
In these applications, you can display a checkerboard pattern that indicates transparency so that you can distin-
guish transparent areas from opaque white areas.
Set how an alpha channel is interpreted
1 Select a clip in the Project panel.
2 Choose File > Interpret Footage or right-click (Windows) or Control-click (Mac OS) and choose Interpret
Footage from the context menu.
3 In the Interpret Footage dialog box, select any of the following Alpha Channel options and click OK:
Ignore Alpha Channel Ignores the alpha channel in the clip.
Invert Alpha Channel Reverses the light and dark areas of the alpha channel. This swaps the transparent and opaque
areas.
If you have difficulty identifying which parts of a clip are transparent, choose Alpha from the Program view menu
in the Program Monitor. Another way to see areas of transparency is to add a bright solid color matte on a track
below the image you are keying.
Adjust the opacity of clips
By default, clips on tracks appear at full (100%) opacity except for areas marked by a clip’s mask, matte, or alpha
channel. Make an entire clip more transparent by setting an opacity value below 100%. When a clip’s opacity value
is set to less than 100%, clips on lower tracks may be visible. At 0% opacity, the clip is completely transparent. If no
clips are stacked below a partially transparent clip, the sequence’s black background becomes visible. You can set a
selected clip’s opacity in the Effect Controls panel or Timeline panel, and you can fade a clip down or up over time
by animating opacity.
Rendering order affects how opacity interacts with visual effects. The Video Effects list is rendered first, then
geometric effects such as Motion are rendered, and then alpha channel adjustments are applied. Within each effects
group, effects are rendered from the top down in the list. Because Opacity is in the Fixed Effects list, it renders after
the Video Effects list. If you want opacity to render earlier or later than certain effects, or if you want to control
additional opacity options, apply the Alpha Adjust video effect.
If you simply want to create a fade to black, consider applying a transition such as Dip To Black to the clip instead
of animating opacity keyframes manually.
See also
“ Alpha Adjust effect ” on page 335
“ Edit keyframe graphs ” on page 289
“ About keyframes ” on page 282
Specify clip opacity in the Effect Controls panel
1 Select a clip in the Timeline panel.
April 1, 2008