NewTek TriCaster TCXD300, User Manual

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14.1 CHROMAKEYING
The method by which part of the image is defined as transparent is generically referred to as
chromakeying, for its dependence on the color values (chrominance) of the video stream.
Note: Internally, LiveMatte actually goes well beyond simple chromakeying techniques to provide
its great realtime results - but we’ll stick with fundamentals for our discussion here.
Chromakeying has become an essential tool in video and film production. Typically, foreground
footage is shot in front of a blue or green screen, and then that background color - the
key color -
is treated as transparent, allowing another image to be inserted.
For example, when you see a television meteorologist in front of a weather map, that person is
almost certainly posed in front of a green screen. The background is ‘keyed out’ and replaced by
computer graphics.
Figure 162
Of course, if you choose inappropriate settings, foreground areas may inadvertently be cut away
as well. Ideal settings require judicious balance between ‘too much’ and ‘too little’. Let’s
consider the tools provided to help you achieve a good result.