THOMSON GRASS VALLEY KayakDD-1, Руководство пользователя

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KayakDD - Digital Production Switcher
Chroma keys are performed by suppressing the backing color in the foreground scene,
cutting a hole in the background, and then combining the two processed signals. When
conditions are ideal, complete suppression of the backing color is possible and the
hole cut in the background will match the suppressed foreground, permitting these two
signals to be added successfully.
This is called an additive chroma key (used when the KayakDD system Foreground
Reshaping feature is off). When conditions do not permit adequate backing color
suppression, the foreground with its backing color suppressed can be multiplied by the
keying signal to prevent contaminating areas of the background outside the keyed
area. This is called a multiplicative chroma key (used when the KayakDD system
Foreground Reshaping feature is on). Setting up a successful chroma key setup
involves many more adjustments than other keys. No amount of adjustment, however,
can overcome problems caused by an improperly set up studio chroma key scene.
2.10.12 Primary and Secondary Color Suppression
As described above, chroma key primary color suppression replaces the old backing
color with black before replacing it with the new background video. It usually has a very
low selectivity and therefore suppresses a wide range of colors. The goal is to
suppress as much of the backing color as possible without affecting foreground
regions.
Secondary suppression is essentially a second chroma keyer that can be used to deal
with areas where the backing color passes through some translucent portion of the
foreground object, like smoke or liquid. This also includes hair since fine detail often
mixes with the backing color. The goal of secondary suppression is to restore the
natural color of the foreground object. In general, medium to high selectivity values will
be used.
Primary and secondary suppression adjustments are used to select the hue to be
replaced and for adjusting the luminance and chrominance levels in the areas of the
picture where suppression is applied.
2.10.13 Flare Suppression
Flare suppression can be used to compensate for backing color reflected onto
foreground objects, or for lens flare (backing color reflections within the camera lens).
In these cases, the foreground object will take on a slight greenish or bluish tint. Flare
suppression subtracts a slight amount of the primary suppression color from the
foreground.
2.10.14 Chroma Key Shadow Generator
The KayakDD system has a shadow generator that can be used to include shadows
that fall on the backing area of the scene in the background.
Shadow offset, range, and density controls are also available that offer control over the
placement and appearance of the added shadow.
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