Grass Valley Kalypso User Manual V.15.0 - Manual (Page 82)

82 Kalypso — User Manual
Section 2 — Concepts
Figure 55. Key Clip, Gain, and Key Control Signal
Clip and Gain control is appropriate for high gain keys (see below), to
easily adjust where the relatively hard transition from background to fill
occurs. In this mode, changing the Clip control moves the threshold up and
down without affecting Gain, which is adjusted separately with its own
Gain control.
High Gain, Low Gain, and Unity Gain
A high gain key has a narrow range, creating harder key edges. A low gain
key has a wider range, creating softer key edges. Linear keys typically use
minimal gain (also called unity gain) to completely preserve the soft edges
of the keys (
Figure 56 ). Note that the Kalypso system also supports keys
that go below unity gain.
Figure 56. Keying Gain Values
On the Kalypso system, Gain has a percentage value. A Gain value of 50%
requires a luminance change of 50% of the distance between black and
white to produce a keying signal ranging from transparent to opaque. A
gain value of 100% (unity gain) uses the entire range between black and
white for this transparent to opaque transition. A gain value of 0% pro-
duces the hard key edges (a high gain key).
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Key Cut
Signal
Key Control
Signal
Key Control
Signal
Inverted
(Hole Cutter)
Video
Retained
Mix of
Background
and Fill Video
Video
Removed
Background Video
Removd
Background Video
Retained
Clip
Gain
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High Gain Low Gain
Clip
Gain
Gain
Gain
Clip
Unity Gain
Clip