Adobe Premiere Pro CS3 - Manual (Page 376)

ADOBE PREMIERE PRO CS3
User Guide
370
Make a color transparent with Color Key
The Color Key effect keys out all image pixels that are similar to a specified key color. This effect modifies only the
alpha channel of a layer.
When you key out a color value in a clip, that color or range of colors becomes transparent for the entire clip.
Control the range of transparent colors by adjusting the tolerance level. You can also feather the edges of the trans-
parent area to create a smooth transition between the transparent and opaque areas.
1 Select a clip in the Timeline panel.
2 Apply the Color Key effect to the clip.
3 In the Effect Controls panel, click the triangle to expand the Color Key effect.
4 Do one of the following to specify the key color:
• Click the Key Color swatch to open the Adobe Color Picker, select a color, and then click OK.
• Click the Eyedropper icon, and then click a color on the computer screen.
5 Drag the Color Tolerance slider to specify the range of color to key out. Lower values key out a smaller range of
colors near the key color. Higher values key out a wider range of color.
6 Drag the Edge Thin slider to adjust the width of the keyed area’s border. Positive values enlarge the mask,
increasing the transparent area. Negative values shrink the mask, decreasing the transparent area.
7 Drag the Edge Feather slider to specify the softness of the edge. Higher values create a softer edge but take longer
to render.
See also
“ Color Key effect ” on page 336
About Chroma Key
The Chroma Key effect specifies which color or range of colors in the clip becomes transparent. You can use this
key for a scene shot against a monochromatic screen, such as a blue or green screen.
The following Chroma Key settings are adjusted in the Effect Controls panel:
Similarity Broadens or reduces the range of the target color that will be made transparent. Higher values increase
the range.
Blend Blends the clip you are keying out with the underlying clip. Higher values blend more of the clip.
Threshold Controls the amount of shadows in the range of color you keyed out. Higher values retain more shadows.
Cutoff Darkens or lightens shadows. Drag to the right to darken shadows, but do not drag beyond the Threshold
slider; doing so inverts gray and transparent pixels.
Smoothing Specifies the amount of anti-aliasing that Adobe Premiere Pro applies to the boundary between trans-
parent and opaque regions. Anti-aliasing blends pixels to produce softer, smoother edges. 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.
April 1, 2008