Key Adjustments (Menus); Chroma Key Adjustments - Sony MVS-8000X User Manual

Key Adjustments (Menus)

This section describes key adjustments made by a menu
operation.
You can adjust the following functions by a menu
operation.
• Chroma Key Adjustment (page 97)
• Key Edge Modifications (page 100)
• Masks (page 103)
• Applying a DME effect to a key (page 104)
• Specifying the Key Output Destination (page 105)
• Key Modify Clear (page 106)
• Blink Function (page 106)
• Video Processing (page 106)

Chroma Key Adjustments

Methods of adjusting the composite obtained from chroma
keying include automatic adjustment with the auto chroma
key function, and manual adjustment carrying out the
necessary processing separately. The optimum results will
be obtained by first carrying out adjustments with the auto
chroma key function, then making any fine adjustments as
required.
The following manual adjustments are possible.
Key active
When this function is off, only the foreground is output
and you can make adjustments of color cancel (see the next
paragraph).
Color cancel
If the foreground image includes shades of the background
color, turn this function on to remove the color from the
foreground image.
Chroma key window
You can adjust the range over which the key signal is
determined as matching the specified hue. When this
adjustment is off the default ranges are used.
Chroma keying generates a key signal based on a
particular color (reference color) in the foreground
(typically a plain blue background), and the "window"
refers to the range of colors which are regarded as
matching this specified reference color to create the key
signal.
As seen on a vectorscope (that is, in the hue-saturation
color space), the range for this matching corresponds to a
truncated sector. This range is specified by two
parameters: the "Angle" parameter, which determines the
range of the hue parameter, and the "Crop" parameter,
which determines the degree of truncation (see the
following figure).
a)
Crop
Range of colors remaining
as foreground
a) The Crop and Angle values do not change even if you use the
auto chroma key function.
Window adjustment
Y balance
In normal chroma keying, the key signal is based on the
chrominance component only, and all elements of the
foreground with the same hue are replaced by the
background. Using the Y balance function, you can specify
a luminance level range within which the key is active, and
replace the specified part by the background.
You can use the Y balance function independently on the
key signal for the composition and the key signal for the
color cancel function. When applied to the key signal for
the composition, this produces the foreground with the
color cancel effect applied. This can therefore be used to
provide an impression of smoke, for example.
When the Y balance function is applied to the color cancel
key, the relevant part is output in its original color without
canceling, and therefore it is possible to combine colors
which are the same color as the background (i.e. typically
blue) in the foreground.
Chroma key shadow
This function provides a more realistic treatment when the
shadow of an object in the field of view falls on the blue
background. Since parts of the blue background darker
than a specified intensity are treated as shadows, there is
no effect on cutting out of the foreground.
Video signal adjustment
You can vary the foreground signal gain, or change the
hue. There are separate adjustments for the gain of the
overall video signal, and Y and C components.
Making auto chroma key adjustments
Auto chroma key is an automatic adjustment function
which allows you to specify a part of the foreground video
(for example, the blue background color) and use it as a
reference for creating the chroma key image.
a)
Angle
Reference color
specified by Hue
setting
Range of colors creating the key
signal (to be replaced by
background signal)
Key Adjustments (Menus)
97