User guide

126
Chapter 6, Setting Up Realtime Effects with Adobe Premiere
• Low Clip Use this to select the lower (darker) luminance values to be
keyed. A
Low Clip setting of 0 represents black, and a setting of 255
represents white. Intermediate settings represent different shades of gray,
from very dark to very light gray.
•
Low Gain Use this to set the range of luminance values you want to be
partially transparent based on the value set by the
Low Clip control. As you
increase the
Low Gain setting, more luminance values become partially
transparent to give you a softer-edged key.
A
Low Gain setting of 1.000 provides the widest range for maximum softness.
Alternately, a gain setting of 0 creates a hard key where the luminance values
are either completely transparent or opaque. You can think of the
Low Gain
control as defining a “Transparent to Opaque” range for keying the dark areas
of your foreground image.
•
High Clip This control is similar to Low Clip, except you use it to select
the higher (brighter) luminance values to be keyed.
•
High Gain This control is similar to Low Gain, except you use it to set the
range of luminance values you want to be partially transparent based on the
value set by the
High Clip control. You can think of the High Gain control
as defining an “Opaque to Transparent” range for keying the lighter areas of
your foreground image.
¦NoteThe values you can select using the Low Clip and Low Gain controls
are dependent on the
High Clip and High Gain controls, and vice versa. This
prevents the low and high controls from keying on the same luminance values.
•
Transparency Use this control to set the overall transparency level of your
foreground image. Higher values indicate higher transparency. For example,
a
Transparency value of 1.000 makes your foreground image completely
transparent, leaving only your underlying image visible.
•
Invert key Select this to invert your key effect, giving you the opposite
result of what you originally selected. Previously transparent areas become
opaque, and opaque areas become transparent.
•
Luma Plot This consists of a luminance spectrum with a plot that shows
each luminance value present in your image as a vertical line in the
histogram. A longer line indicates a higher amount of pixels in your image of