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UltraChrome 2 Chroma Key
Engine
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.
•
HR 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.
• HR 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.
The UltraChrome 2 chroma keyer uses an independent
chroma key engine to produce the video and alpha
components of the key. These internal video streams
can be composited in a MiniME
™
keyer, or fed out two
separate video streams to an external device, such as a
video server.
To Select the Chroma Key on a
Keyer
The outputs of the chroma key engine must be selected
on a key bus to be properly keyed and to adjust the
chroma key parameters.
1. Click Navigation Menu > Live Assist >
MiniME .
2. Click the Key
X
button for the keyer you want to
view the chroma key on.
3. Click Auto Select .
4. Click Key Fill: and select CK
X
for the chroma
key you want to use.
To Set Up a Chroma Key
Set up the chroma key with the source you want to use
and adjust the parameters. Ensure that the chroma key
output has been selected on a keyer so that you can
view the output as you adjust the parameters.
1.
Click
Navigation Menu
>
Live Assist
>
Chroma Key .
2. Click CK X for the chroma key engine you want
to use.
3. Click CK Source and select the video source you
want to use for the chroma key.
Note: You can only select a physical input, frame delay,
or a Media-Store for a chroma key. You can also select
an Aux Bus, but the source selected on the Aux Bus must
be valid for the chroma key.
4.
Click Setup (only required if you are using a
separate 0:4:4 source).
5.
Click the Use 0:4:4 Source button to turn
UltraChromeHR with a separate 0:4:4 chroma
source on. Ensure that the chroma key source and
0:4:4 UltraChromeHR signals are properly set up.
Refer to To Assign an 0:4:4 Stream to a Source on
page 29 for information on assigning a source
as an 0:4:4 input.
Tip:
The
Debug Output Source
buttons are for
diagnostic purposes only. Adjust these settings only when
instructed to do so my Ross Video Technical Support.
6. Click Parameters .
7. Click the Color button for the color of the
background you are using for your chroma key.
Note: The scene must contain at least 5% of the desired
chroma key color for the chroma key to properly key out
that color.
8. Click Init .
9. Click 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
14 • UltraChrome 2 Chroma Key Engine — Carbonite Black UltraChrome User Manual (v1.0)