THOMSON GRASS VALLEY KayakDD-1, User Manual

Page: 41 / 448

KayakDD - Digital Production Switcher
2.10.10 Luminance Key and Self Key
A luminance key uses the luminance of an incoming source to specify where to cut the
hole in the background. The earlier example of a matte fill key is a type of luminance
key. 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 14
Luminance Keying (Self Key)
Clip and Gain (or Clip Hi/Lo) controls for luminance keys offer wide adjustment ranges.
On the KayakDD system, an S-shaping function is also applied to the edges of
luminance keys.
User Manual 41