GRASS VALLEY zodiak, User Manual

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Zodiak User Manual 381
Chroma Key Operating Notes
Key Controls
The purpose in adjusting
Clip Hi
and
Clip Low
is to cause the proper hole to
be cut in the background. All areas of the backing color should be full back-
ground while all areas of the foreground should make the background
completely invisible. The easiest way to do this is to observe the key signal
while making your adjustments.
The smaller the difference between
Clip Hi
and
Clip Low
, the higher the keyer
gain. High gain amplifies noise present in the transition between trans-
parent and opaque. The correct setting is with
Clip Hi
and
Clip Low
set to just
barely achieve opacity and transparency, respectively.
1. Touch the stage 2
Key Controls
data pad to activate these controls. You can
now manually adjust keyer clipping controls.
2. Touch
Show Key
in the Keyer menu ( Figure 259 ) and look at the M/E
preview output on a picture and waveform monitor.
Figure 259. Key Controls
3. Adjust
Clip Hi
so that all areas of the foreground objects are white. If
Clip
Hi
is set too low (too far clockwise), much of the translucent areas will
be forced to be fully opaque, hardening the key and darkening the
transition area between background and foreground.