Grass Valley Karrera Video Production Center v.4.0 - Manual (Page 59)

KARRERA — User Manual 59
MEs and Keyers
Key Controls
The purpose in adjusting Clip H i 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 Lo , 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 Lo 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. Select Show Key in the Keyer menu ( Figure 23 ) and look at the ME
preview output on a picture and waveform monitor.
Figure 23. 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.