User Guide

CHAPTER 7
260
Working with Masks and Transparency
4 Copy the mask or keyframes and paste to the new layer.
Creating track mattes and traveling mattes
When you want one layer to show through a hole in another layer, set up a track matte.
You’ll need two layers—one to act as a matte, and another to fill the hole in the matte.
You can animate either the track matte layer or the fill layer. When you animate the track
matte layer, you create a traveling matte. If you want to animate the track matte and fill
layers using identical settings, consider precomposing them (see “Understanding precom-
posing” on page 348).
Using alpha channel or luminance values for a track matte
Define transparency in a track matte using values from either its alpha channel or the
luminance of its pixels. Using luminance is useful when you want to create a track matte
using a layer without an alpha channel or a layer imported from a program that can’t
create an alpha channel. In both alpha channel mattes and luminance mattes, pixels with
higher values are more transparent. In most cases, you use a high-contrast matte so that
areas are either completely transparent or completely opaque. Intermediate shades should
appear only where you want partial or gradual transparency, such as along a soft edge.
To create a track matte:
1 Click the Switches/Modes button at the bottom of the Timeline window. The Transfer
Modes panel appears in place of the Layer Features panel. You can also show the Transfer
Modes panel and the Switches panel simultaneously. See “Optional panels” on page 117
for information on showing panels.
2 Arrange two layers in the Timeline window. Make sure that the designated matte layer
is directly above the designated fill layer.
3 From the TrkMat menu for the fill layer, define transparency in the next layer above by
choosing one of the following:
No Track Matte No transparency created; next layer above acts as a normal layer.
Alpha Matte Opaque when alpha channel pixel value is 100%.
Alpha Inverted Matte Opaque when alpha channel pixel value is 0%.
Luma Matte Opaque when a pixel’s luminance value is 100%.
UG.book Page 260 Wednesday, February 21, 2001 12:05 PM