Grass Valley Kayak HD v.6.9.3 - Manual (Page 57)

Kayak — User Manual 57
Keying
S-shaping is generally not applied to linear keys because the external
device usually applies an S-shaping function when it generates the key cut
and key fill signals. S-shaping should not be applied twice.
Additional Keying Controls
The following additional controls are available for keying.
Key Invert
Keys can be inverted, causing holes to be cut in the background where a
normal key retains the background, and vice versa. Key invert makes the
white areas of the key cut signal produce transparency, and the black areas
produce opacity, the opposite of a standard key.
Masking
Masking defines areas that are protected from keying (Inhibit Mask) or
always key (Force Mask). The shape of the mask can originate from a wipe
pattern generator or by a selected mask signal (typically a key fill signal
delivered via the Utility bus).
With the Kayak RAM Recorder (Still Store), the mask signal can be a frozen
page of video or a key fill. Complex mask shapes are often easier to draw
by hand than to create with multiple wipe patterns.
Opacity
The opacity of a key can be adjusted. When opacity is reduced below 100%
some background video is allowed to show through areas where it is nor-
mally excluded. Key opacity is an adjustment to the overall intensity of the
key, and is separate from Clip and Gain controls. Note that a common
mistake is to set opacity to zero and forget that adjustment was made,
which can cause confusion later when that key is selected but not visible.
Key Positioning
Key positioning allows slight adjustment of the horizontal position of the
key cut signal relative to the key fill signal. This is useful if the timing of the
two signals at the switcher inputs are not matched properly. This is gener-
ally only a problem if the cut or fill follow analog paths from source to
switcher or if the source has video/key timing adjustments which have
been set to compensate for other delays within the facility.
Key Size
Key size allows the key cut signal to be narrowed slightly. This can greatly
enhance self keys and chroma keys that have been reshaped.