Instruction Manual

Chapter 13 Keying 505
Luma Keyer lter
Luma Keyer lter overview
The Luma Keyer lter pulls a key from an image or clip based on a selected range of image
lightness. Although typically used to key out a white background behind a foreground subject,
the Luma Keyer lter can also be used to generate creative eects by turning a narrow range
of image brightness transparent. The Luma Keyer lter can also isolate rasterized logo and text
graphics from a black or white background.
Luma keys are most eective when you’re keying a subject with a range of lightness dierent
from the area you’re turning transparent. For example, if you’re keying a black background, the
foreground subject should not have have deep shadows or dark areas that might get keyed with
the background. Generally speaking, shadows and highlights in the image usually make this a
dicult lter for pulling a perfect key.
For a description of the Luma Keyer lter parameters, see Luma Keyer lter controls on page 505.
Luma Keyer lter controls
The Luma Keyer lter appears to have similar controls to the Keyer lter. However, because the
Luma Keyer generates keys based on a simple range of lightness in an image, rather than a range
of color and lightness, its controls are simpler.
Basic controls
•
Luma: Drag the handles of this grayscale gradient to adjust tolerance and softness in the
matte. When you rst apply the Luma Keyer lter to an image layer in Motion, the Luma
control displays two handles: a Tolerance handle in the upper right, and a Softness handle in
the lower left. Dragging the top handle to the left reveals a second tolerance handle. Together,
these handles dene the range of image lightness used to dene the core transparency of
the resulting matte. The range of lightness turned transparent is indicated by a checkerboard
pattern behind the gradient. Two handles under the gradient dene the softness, or edge
transparency, of the key. (The second softness handle may not be visible until you drag the
two tolerance handles left.) Dragging either of the lower softness handles further out and
away from the upper tolerance handles results in a key with softer edges. You can also drag
the slope in the graph to adjust the softness handles.
•
Invert: Select this checkbox to reverse which area is transparent and which is opaque.
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