Adobe PREMIERE PRO 2, Руководство пользователя, Страница: 368 / 448

ADOBE PREMIERE PRO 2.0
User Guide
362
Mask Only
Displays only the clip’s alpha channel. Black represents transparent areas, white represents opaque areas,
and gray represents partially transparent areas.
Drop Shadow
Adds a 50% gray, 50% opaque shadow offset 4 pixels down and to the right from the opaque areas of
the original clip image. This option works best with simple graphics such as titles.
See also
“About keying” on page 355
Blue Screen Key and Green Screen Key
The Blue Screen Key and Green Screen Key create transparency from true chroma blue and true chroma green. Use
these keys to key out well-lit blue or green screens when creating composites.
The following Blue Screen and Green Screen Key settings are adjusted in the Effect Controls panel:
Threshold
Sets the levels of blue or green that determines transparent areas in the clip. Dragging the Threshold slider
to the left increases the amount of transparency. Use the Mask Only option to view the black (transparent) areas as
you move the Threshold slider.
Cutoff
Sets the opacity of the nontransparent areas specified by the Threshold setting. Dragging the Cutoff slider to
the right increases the opacity. Use the Mask Only option to view the white (opaque) areas as you drag the Cutoff
slider.
Smoothing
Specifies the amount of anti-aliasing (softening) applied 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.
Mask Only
Displays only the clip’s alpha channel. Black represents transparent areas, white represents opaque areas,
and gray represents partially transparent areas.
A subject is photographed against a green background (left). The Green Screen Key effect is applied (right) to superimpose the subject over the
underlying track.
See also
“About keying” on page 355
Using the Non Red Key
The Non Red Key creates transparency from green or blue backgrounds. This key is similar to the Blue Screen and
Green Screen Keys, but it also lets you blend two clips. In addition, the Non Red Key helps reduce fringing around
the edges of nontransparent objects. Use the Non Red Key to key out green screens when you need to control
blending, or when the Blue Screen or Green Screen Keys don’t produce satisfactory results.