Adobe Flash Professional CS6 Adobe Flash Professional CS6 Classroom In A Book | Page 334

using a green Screen
Professionals often film people in front of solid green or blue backgrounds so they
can easily remove, or key, the background in a video editing application such as
Adobe After Effects. Then the person is merged with a different background. The
image of the zoo director was filmed in front of a green screen, which was removed
in After Effects. Follow these steps to use a green screen:
1 Shoot footage in front of a green
screen:
• Use a green background that is
flat, smooth, and free of shadows
so the color is as pure as possible.
• Minimize the light that reflects off
the green screen onto the subject.
• Keep movement to a minimum for
Flash Video; use a tripod if possible.
2 Remove the background in After
Effects or other video editing
application:
• In After Effects, import the
file as footage, create a new
composition, and drag it onto
the Composition Timeline.
• Create a garbage mask to
roughly outline the shape and
remove most of the background.
But be sure the subject never
moves outside the mask!
• Use the Color Range keying
effect to delete the rest of the
background. You may need to do
some fine-tuning with the Matte
Choker and Spill Suppressor
effects. A spill suppressor
removes the light that splashes
onto the edges of the subject.
3 Export the file to FLV format:
Export the video file to Flash Video
(FLV) format directly from the video
editing application. Be sure to select
Encode Alpha Channel. The alpha
channel is the selection around the subject. Encoding the alpha channel ensures
that the video exports without a background.
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