2011

Table Of Contents
The Alpha Levels tool UI has the following parameters.
(a) Lift/Gain fields (b) Minimum Output slider and field (c) Minimum Input slider and
field (d) Luma Remapping Curve (e) Maximum Input slider and field (f) Maximum
Output slider and field
Lift Adjust the Lift to add an overall offset to the matte.
Gain Adjust the Gain to adjust a scaling factor for the matte. Lift, Gain,
Input and Output are animatable attributessee
Marking Attributes for
Keyframing
on page 674.
Minimum Output slider Drag to remap input blacks to dark gray.
Minimum Input slider Drag to the right to remap dark grays as black.
Luma remapping curve View the changes you make in this curve.
Maximum Input slider Drag to the left to remap light grays as white.
Maximum Output slider Drag to the left to remap output whites to light
gray.
Blend Alpha
The Blend Alpha tool is used to blend two mattes together under the optional
control of a third matte. It has front, back, and matte inputs. It extracts a
matte from the front image and composites it over the alpha channel of the
back input using a choice of blend modes. The coverage of the front can be
controlled by the matte input. The back is the primary input; the output
inherits the format of the back input; this tool only affects alpha; if the back
is an RGBA image, the color part is simply copied to the output.
NOTE The alpha output of this tool is always clamped to the [0,1] interval.
The Blend Alpha tool has the following parameters:
344 | Chapter 16 2D Compositing