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5. Press Trans Rate and use the Trans Rate
knob to set the independent key transition
rate.
6. Toggle Transparency to On and use the
Transp. knob to adjust the transparency of
the key from opaque ( 0% ) to fully
transparent ( 100% ).
7. Toggle Additive to temporarily override the
shaped/unshaped key settings for the
selected source.
•
On — turn shaped keying on for the
source.
• Off — turn unshaped keying on for the
source.
UltraChrome 2 Chroma Key
An UltraChrome Chroma Key is a key in which
the hole is cut based on a color value, or hue,
rather than a luminance value or alpha signal.
The color is removed and replaced with
background video from another source. The
default color is blue.
UltraChrome 2 can work in two modes,
depending on the lighting conditions and subject
matter used for the chroma key.
• Wedge Key — Based on the standard chroma
keyer and discriminates between the color
vector angle and level of the background
color vs the color vectors and levels in the
foreground components. This produces very
good results under ideal conditions.
However, if the scene includes high detail
luma content in edge regions, these may not
be included in the output.
• Detail Key — Differs from the standard
chroma keyer in that it adds luminance
dependency to a three-dimensional spherical
color discriminator. This chroma keyer can
develop subtle video and alpha shapes and
discriminate high detail luma content in edge
transition areas. However, this design may
have problems with content where
background and foreground levels are
similar within the video itself.
Tip: UltraChrome 2 also offers the option to combine these two
modes to offer good capture of high luma detail in the edge
regions as well as compensation for similar foreground and
background levels.
UltraChrome 2 includes unique Automatic
Background Analysis that can develop key
edges with luma values consistent with those of
the new background - eliminating the light or
dark key halos. In addition, background color
values are averaged and can be applied to spill
areas to add lighting realism to the final
composition.
To Set Up a Chroma Key
Set up the chroma key with the source you want
to use and adjust the parameters.
1. Press the SEL button on the Keyers module
for the key you want to set up and select a
video source on the Key bus.
Tip: The SEL button allows you to quickly select the keyer
you want to work with and assign the Key bus to the keyer.
On the Double-Down control panel, the top button row is
assigned to the even numbered keyers (2,4,6) and the
button row below is assigned to the odd numbered keyers
(1,3,5). This can be changed with the DD Key Delegation
personality option.
2. Press CHROMA KEY .
3. Press the Color button ( Red , Magenta , Blue ,
Cyan , Green , Yellow ) for the color of the
background you are using for your chroma
key.
4. Press Initialize Key .
The chroma key engine initializes and
attempts to remove the selected background
color from the video. Any further adjust is
only required if you want to adjust aspects
of the key.
5. Press the Key Type button for the chroma
key mode you want to use.
•
Wedge Key — Based on the standard
chroma keyer and discriminates between
the color vector angle and level of the
background color vs the color vectors
and levels in the foreground components.
• Detail Key — Differs from the standard
chroma keyer in that it adds luminance
dependency to a three-dimensional
spherical color discriminator.
• Combination Key — Combine the two
modes to offer good capture of high luma
detail in the edge regions as well as
compensation for similar foreground and
background levels.
Note: All adjustments are always available, even if they
are not applied by the selected mode.
Tip: Although adjustment can be made to either key type
while the combined output is selected, it is recommended
that adjustments of either key type be conducted with only
that key type selected. This eliminates the possibility of the
42 • Keying — Ultrix Acuity Operation Manual (v10.1)