Chroma Key: Colour Separation Overlay
These are the names given to an electronic method of combining the outputs from two or more TV cameras or other sources (such as film scanners, etc.). The system allows parts of one picture to be inlaid into another in such a way that the divisions cannot be detected.
The brain of the device is an electronic switch that ‘flips’ over when fed with a certain colour signal from the primary picture. If for instance the control colour is blue, wherever that blue appears in the original scene the switch automatically removes it and substitutes pictures from the second source.
The equipment is highly selective so that only the precise colour hue will trigger the switch, all other tones of the same colour leaving ...
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