THOMSON GRASS VALLEY KayakDD-1, User Manual

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KayakDD - Digital Production Switcher
2. Adjust Hue, Selectivity, Chroma, and Luma primary suppression to eliminate
the backing color.
•
Hue can be set accurately with Auto Setup. Hue should center on the
primary color of the backing area of the foreground scene. Depending
cking color.
•
Selectivity may need to be increased if there are colors in the
foreground image that are being suppressed. Selectivity should be
set as low as possible without including colors that should not be
suppressed. For example, when keying on green, a greenish yellow
shirt might be affected by the suppression. If so, adjust the selectivity
a suppression can be set accurately with Auto Setup. To
adjust, increase suppression and observe the backing color
e through the center of the vector scope. With
increased selectivity, this line will become an arc.
g area with FG Only selected, or if the shading adversely
affects the background image. Primary Luma suppression is hardly
ever desired when FGD Fade is on. To adjust, increase
Luma
suppression and observe the backing color move toward black. You
want to make the backing color just black. Increasing this control too
much will make the chroma key hard and noisy. When not enough,
highlights will be added to the background. Note that incomplete
luminance suppression is not necessarily bad. The highlights added to
the background will match the shading on the backing wall, adding
natural shadows and perhaps eliminating the need to add artificial
shadows.
•
All the above adjustments may need to be revisited later.
3. Another potential artifact of chroma keying is a tinting of the overall foreground
subject due to lighting splash from the backing color or lens flare. Flare
Suppression adds a small amount of color to the entire foreground image to
cancel the splash or flare. Typically less than 2% of the backing color is
needed to neutralize the flare.
on where Luma and Chroma primary suppression are set, adjusting
Hue may not make any noticeable change on the scene. Chroma
suppression should be preset to 100% and Luma set to 0%. Hue can
then be tuned to remove the ba
high enough to reject that color. Too high a selectivity is one of the
classic causes of a noisy key. If the foreground subject is stationary,
consider using a force mask instead of increasing selectivity.
•
Chrom
Chroma
dot on the vector scope move toward the center. You want to center it
exactly, so no chroma exists in the backing area. 100% chroma
suppression is the correct setting for all chroma keys. At this point, you
will probably see a lin
•
Luma suppression adjustments may be necessary if shading is visible
in the backin
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