GRASS VALLEY INDIGO, User Manual

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52 INDIGO AV Mixer User Manual
Section 5 — Basic Operation
Luminance Key
A luminance key uses the luminance of an incoming source to specify where
to cut the hole in the background. Luminance keying is typically done on
sources that do not have an accompanying key cut signal, like a video
camera. The key cut signal must be generated from the incoming video
signal, using clip and gain controls. When only one source is used for both
key cut and key fill, the key is called a Self key or Video key. The same key
source signal is multiplied by the key cut signal to create the key fill, and
then the signals are summed.
Figure 30. Luminance Key
Clip and Gain controls for luminance keys offer wide adjustment ranges.
X
X
+
Background Video Key Hole Background
Key Control
Key Source (video only) Key Fill
Completed
Invert
Luminance Key
Gain
Clip