2011

DescriptionTool
A simple matte modifier that drops the alpha channel from its
primary input—see Drop Alpha on page 356.
Drop Alpha
Lets you refine the edges of a matte—see Edge Tool on page 356.Edge
Extracts the alpha channel from its primary input—see Extract Alpha
on page 357.
Extract Alpha
Lets you modify the transparency of an image—see Fade Tool on
page 357.
Fade
Inverts the alpha channel of its primary input—see Invert Alpha on
page 358.
Invert Alpha
Excellent for removing impulse noise—see Median Alpha on page
358.
Median Alpha
Remaps the alpha—see Remap Alpha on page 358.Remap Alpha
Create an alpha channel for an image based on a component from
a second image—see Set Alpha Tool on page 360
Set Alpha
Alpha Levels
The Alpha Levels tool is one of the tools used for matte cleanup tasks during
the keying process. When used as a tool defined by the keyer tool's dependency
graph, the Alpha Levels tool applies its effect to the alpha component of the
keyer's output. You can clean up the matte by manipulating the input/output
luma remapping curve, by adjusting the input and output luma fields or sliders,
or by adjusting the lift and gain. The Alpha Levels tool also allows you to
invert the matte. The Alpha Levels tool is located in the Alpha tools folder in
the Tools tab.
The histogram indicates the distribution of luma values in the input source
alpha channel with gray vertical bars along the X-axis. The curve illustrates
the resulting luma value. For example, if you drag the part of the curve that
represents the darker input grays upwards, the curve over that region becomes
lighter.
Since the Alpha Levels tool affects the alpha and is typically applied to the
output of a keyer tool, such as the Luma Keyer or the Diamond Keyer, your
dependency graph should include, as a minimum, one source and a keyer.
Alpha Levels | 343