MacroSystem Bluebox World - Manual (Page 16)

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6.3.1-4 Bluescreen
The “Bluescreen“ Bluebox mode represents
an alternative to the “Standard“ mode, and
can particularly yield better results when the
selected color in the foreground video scene is
subject to strongly differing illumination levels.
However, in contrast to “Standard“ mode, the
color specified for “Bluescreen“ is restricted to
one of the basic colors - red, green or blue.
It is not possible with “Bluescreen“ to select
a spectrum of colors ranging, for instance,
from blue through blue-green to green,
since relatively narrow color tolerances are
specified. The basic color, on the other hand,
may be subject to considerable differences in
illumination level and therefore in brightness.
Three settings have to be made:
• Mode
A choice must be made between the three
basic colors - red, green or blue. If none of the
three basic colors appears in the foreground
scene, the “Bluescreen“ mode cannot be used.
• Tolerance
The “Tolerance“ slider specifies how far the
hue may diverge from the basic color selected.
The tolerance can only be adjusted within the
color range of the selected background color,
from lime-green to dark-green, for instance,
but cannot extend to more than one color.
• Matte density
This controller allows compensation for
brightness differences within the selected
color. The “Matte density“ slider brightens
areas such as can occur at the edges of
objects. This function can also improve the
representation of edges.
6.3.1-5 Chroma
The “Chroma“ mode is another option (besides
“Standard“ and “Bluescreen“). Operation is
identical to that of the “Standard“ mode, but
the “Chroma“ mode works with only the hue,
independent of saturation or brightness.
6.3.1-6 Color
Whereas the “Standard“ Bluebox mode only
considers the hue and the color saturation, in
the “Color“ mode all the color values, including
the hue, saturation and brightness are jointly
evaluated. Operation in “Color“ mode is
identical to that in “Standard“ mode.
6.3.1-7 Color and Luma
Color and brightness are the joint selection
criteria in this Bluebox mode. Separate tolerance
values can be set for the brightness and for the
color.
Three settings have to be made:
• Color
The color selection corresponds to that of the
“Select area“ option in the “Standard“ mode.
A rectangle whose position and size can be
freely selected encloses a specific color region.
It is not necessary here to enclose a specific
object, such as a person, but rather just the
largest possible range of the colors that are
later to be made“invisible“, (i.e. transparent).
The rectangle should cover the largest possible
area, and enclos the widest possible range of
brighter and darker regions of varying color
shadings.
• Tolerance Color
The “Tolerance Color“ slider specifies how far
the color may diverge from the selected area.
• Tolerance Brightness
The “Tolerance Brightness“ slider specifies
how far the brightness may diverge from the
selected area.
6.3.1-8 Luma 1
In the“Luma 1“ mode only the brightness of the
image is used as the single selection criteria,
regardless of the color.
Two settings have to be made:
• Brightness
The brightness range is set as a percentage
through the slider. A value of 0 percent means
that all the dark components of the foreground
video appear transparent.
• Tolerance
The “Tolerance“ slider specifies how far the
brightness may diverge from the selected area.
If the value is set too high, the foreground will
become transparent, whereas if the value is
too low it may mean that some parts of the
background remain visible. We recommend
that the tolerance is chosen in such a way
that only minimal residues of the brightness
range that is to be removed remain visible,
and that afterwards these residual regions are
smoothed away under “Select alpha“ with the
aid of the “Transition“ function.