Belden Grass Valley GV Korona, User Manual

Page: 78 / 433

78
Video Mix/Effects
Reshape a Chroma Key Using Auto Setup
7 Use the joystick to position the cursor on the backing color. Select a darker area, if one
exists, to optimize the backing color suppression.
8 Press the button on top of the joystick. The chroma key will be set up automatically
using the average of the colors selected by the cursor box. Because Reshape was off,
fine edges of the key will be preserved.
9 If this chroma key is acceptable, you are done. If set, lighting, or other conditions
prevent the result from being acceptable, you need to decide whether to adjust the
chroma key manually or use Auto Setup with Reshape.
• Manual adjustment permits retention of fine edge detail (see the Switcher Concepts
Manual for more information). In particular, if there are problems with translucent
areas (hair, smoke) secondary suppression controls can be useful.
• Auto Setup with Reshape produces a chroma key with harder edges, but
accommodates wider set variations (see below).
Reshape a Chroma Key Using Auto Setup
If the set is lit unevenly or has other problems, Reshape is available to help solve the
problem. A better alternative, if time permits, is to adjust the lighting on the set to even out
the backing color. This may improve the key so that Reshape is not needed.
1 If you decide you must use Reshape, follow the Auto Setup procedure in Configure
Auto Setup , on page 77 but select Reshape in the Keyer menu to turn it on (its green
indicator will illuminate). After selecting the backing color area and selecting the top
button on the joystick, the chroma key will be set up with coarser values better able to
handle set variations.
2 If this chroma key is acceptable, you are done. If you are still not satisfied, you can fine
tune the chroma key using manual adjustments.
Adjust Chroma 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 background 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 transparent and opaque. The correct
setting is with Clip Hi and Clip Lo set to just barely achieve opacity and transparency,
respectively.
1 Select 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 and look at the M/E preview output on a picture
and waveform monitor.