5.5

1060Motion User Guide
By default, the slope of the left and right sides of the Luma graph has a slight “S” curve.
You can modify the shape of the curve by adjusting the Luma Rolloff slider (described
below).
Note: The luma softness handles may extend past the outer boundaries of the
Luma control. This is due to the floating-point precision of the Keyer filter, and is
an expected behavior.
• Chroma Rolloff: A slider to adjust the linearity of the chroma rolloff slope (displayed in
the small graph to the left of the Chroma control). Chroma rolloff modifies the softness
of the matte around the edges of regions that are affected most by the Chroma control.
Lowering this value makes the slope of the graph more linear, which softens the edges
of the matte. Raising this value makes the slope of the graph steeper, which sharpens
the edges of the matte.
• Luma Rolloff: A slider to adjust the linearity of the luma rolloff slope (the ends of the
bell-shaped luma curve displayed in the Luma control). Luma rolloff modifies the
softness of the matte around the edges of regions that are affected most by the Luma
control. Lowering this value makes the slope between the upper and lower handles in
the Luma control more linear, which increases edge softness in the matte. Raising this
value makes the slope steeper, sharpening the edges of the matte and making them
more abrupt.
• Fix Video: Select this checkbox to apply subpixel smoothing to the chroma components
of the image, reducing the jagged edges that result from keying compressed media
using 4:2:0, 4:1:1, or 4:2:2 chroma subsampling. Although selected by default, this
checkbox can be deselected if subpixel smoothing degrades the quality of your keys.
Matte Tools controls
Click the disclosure triangle in the Matte Tools row to reveal controls for post-processing
the transparency matte generated by the previous sets of parameters. These parameters
don’t alter the range of values sampled to create the keyed matte. Instead, they alter the
matte generated by the Keyer filter’s basic and advanced controls (in the Color Selection
parameter group), letting you shrink, expand, soften, or invert the matte to achieve a better
composite.
The Matte Tools group contains the following controls:
• Levels: A grayscale gradient to alter the contrast of the keyed matte. Drag this control’s
three handles to set the black point, white point, and bias (distribution of gray values
between the black point and white point). Adjusting the contrast of a matte can be
useful for manipulating translucent areas of the key to make them more solid (by
lowering the white point) or more translucent (by raising the black point). Dragging the
Bias handle (the gray tag under the gradient) right erodes translucent regions of the
key, while dragging the Bias handle left makes translucent regions of the key more solid.