Keying, Keying overview and tips – Adobe After Effects CS3 User Manual
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AFTER EFFECTS CS3
User Guide
268
Motion blur settings for a layer and a composition
A. Enable Motion Blur composition switch B. Motion Blur layer switch
1
Select one or more masks.
2
Choose Layer > Masks > Motion Blur, and choose one of the following options:
Same As Layer
The mask will have motion blur only if the layer’s Motion Blur switch is selected.
On
The mask will have motion blur regardless of the setting of the layer’s Motion Blur switch.
Off
The mask will not have motion blur.
See also
Keying
Keying overview and tips
Keying is defining transparency by a particular color value or luminance value in an image. When you key out a value,
all pixels that have colors or luminance values similar to that value become transparent. Keying makes it easy to
replace a background, which is especially useful when you work with objects too complex to mask easily. When you
place a keyed layer over another layer, the result forms a composite, in which the background is visible wherever the
keyed layer is transparent.
After Effects includes several built-in keying effects, as well as the Academy Award-winning Keylight effect, which
excels at professional-quality color keying. For information on the Keylight effect, see its documentation in this
folder: Adobe After Effects CS3/Additional Documentation/Keylight.
To see a video tutorial on keying with Keylight, visit the Adobe website at
.
Adobe® Creative Suite® Production Premium Edition also includes Adobe Ultra®, which can quickly key out a poorly
lit background shot with a low-quality webcam. For more information on Adobe Ultra, visit the Adobe website at
.
You often see composites made with keying techniques in movies, for example, when an actor appears to dangle from
a helicopter or float in outer space. To create this effect, the actor is filmed in an appropriate position against a solid-
color background screen. The background color is then keyed out and the actor’s scene is composited over a new
background.
The technique of keying out a background of a consistent color is often called bluescreening or greenscreening,
although you don’t have to use blue or green; you can use any solid color for a background. Magenta screens have
been used for keying work in some very successful feature films. Other common terms for this sort of keying are
color keying and chroma keying.
A
B