“Talking Head” Video and Alpha Channels


You have seen this technique used on your local television station’s weather broadcast. The weatherman will stand in front of a radar image and start pointing out the features in the image that are important. If you were in the studio while all this is going on, it would be rather disconcerting. The weather broadcaster would be standing in front of a green or blue wall and pointing to it while delivering the broadcast. What happens is that he or she is looking at a monitor in which they are standing in front of the radar image “behind” them. The green (see Figure 5-1) or blue color is being “keyed out” of the signal and replaced with the radar image.
Figure 5-1

The “Talking Head” video. Note the green screen in the background.


Video Object Video Layer Green Background Alpha Channel Green Screen 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Tom Green and Adam Thomas 2008

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