Autodesk 62205-051408-9001 User Guide - Page 229

Difference Keyer Controls, RGB or YUV, Output, R, G, or B, Tolerance, Softness, Back Source, Reset

Page 229 highlights

Creating Alpha Channels with Keyers ❚❘❘ The difference matte effect calculates the difference between corresponding pixels of the two source images. The value of the pixel in the back image is subtracted from the value of the corresponding pixel in the front image, and the resulting absolute value is used in the difference matte. The matte is created using the Tolerance and Softness values that you specify. The Tolerance value specifies the difference level that is considered black. A higher Tolerance value includes more black in the matte. The Softness value is used to soften the transition between the light areas and the dark areas of the matte by adjusting the amount of gray at its edges. Gray information is not included in the matte when the Softness is zero. Use a higher Softness value to increase the gray. Difference Keyer Controls The Difference Keyer Controls panel includes the following elements. RGB or YUV-Click one of these buttons to specify the color model to use for the difference matte. Output-Click a button under this heading to specify a difference key output. You can choose Front, Back, Matte, or Result. Gain-Use this slider to boost the matte. The Difference Keyer multiplies the values of the pixels in the result clip by the Gain. Lift-Use this slider to add the Lift value to all pixels in the difference matte. R, G, or B-Enable the color channel(s) to use for the difference matte. You can use any of the Y, U, or V channels in the YUV color model, or any of the R, G, or B channels in the RGB color model. Tolerance-Set the tolerance for the matte by clicking the color box next to the Tolerance field in the same row as the color channel you are using. Drag the color picker around the area of the image to matte out. Note: You can also set the tolerance for the matte directly in the Tolerance fields. Softness-Set the softness for the matte using either the Softness field or the color box beside its field. Note: You can also set the softness for the matte directly in the Softness fields. Back Source-The Back Source field displays the operator that you are comparing to the front layer. Click the Set button to pick a new Back Source. Reset-Click this button to reset Difference Keyer parameters to their default settings. Every value is reset but the currently selected back source is kept. Reset All-Click this button to reset all Difference Keyer parameters to their default settings, including the back source. To use the Difference Keyer: 1. Load a front clip and a back clip into a composite. 2. In the Workspace panel, select the front layer. 3. Choose Operators | Keying | Difference. The Choose Background Source dialog appears. 213

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Creating Alpha Channels with Keyers
213
❚❘❘
The difference matte effect calculates the difference
between corresponding pixels of the two source
images. The value of the pixel in the back image is
subtracted from the value of the corresponding pixel
in the front image, and the resulting absolute value is
used in the difference matte.
The matte is created using the Tolerance and
Softness values that you specify. The Tolerance value
specifies the difference level that is considered black.
A higher Tolerance value includes more black in the
matte. The Softness value is used to soften the
transition between the light areas and the dark areas
of the matte by adjusting the amount of gray at its
edges. Gray information is not included in the matte
when the Softness is zero. Use a higher Softness
value to increase the gray.
Difference Keyer Controls
The Difference Keyer Controls panel includes the
following elements.
RGB or YUV
—Click one of these buttons to specify
the color model to use for the difference matte.
Output
—Click a button under this heading to
specify a difference key output. You can choose
Front, Back, Matte, or Result.
Gain
—Use this slider to boost the matte. The
Difference Keyer multiplies the values of the pixels in
the result clip by the Gain.
Lift
—Use this slider to add the Lift value to all pixels
in the difference matte.
R, G, or B
—Enable the color channel(s) to use for
the difference matte. You can use any of the Y, U, or
V channels in the YUV color model, or any of the R,
G, or B channels in the RGB color model.
Tolerance
—Set the tolerance for the matte by
clicking the color box next to the Tolerance field in
the same row as the color channel you are using.
Drag the color picker around the area of the image to
matte out.
Note:
You can also set the tolerance for the matte
directly in the Tolerance fields.
Softness
—Set the softness for the matte using
either the Softness field or the color box beside its
field.
Note:
You can also set the softness for the matte
directly in the Softness fields.
Back Source
—The Back Source field displays the
operator that you are comparing to the front layer.
Click the Set button to pick a new Back Source.
Reset
—Click this button to reset Difference Keyer
parameters to their default settings. Every value is
reset but the currently selected back source is kept.
Reset All
—Click this button to reset all Difference
Keyer parameters to their default settings, including
the back source.
To use the Difference Keyer:
1.
Load a front clip and a back clip into a composite.
2.
In the Workspace panel, select the front layer.
3.
Choose Operators | Keying | Difference.
The Choose Background Source dialog appears.