Autodesk 62205-051408-9001 User Guide - Page 638

Using the Plot Tool, Extracting a Key Based on Luminance, Adjusting the Matte, Using the Histogram

Page 638 highlights

23 Keying 2. Do one of the following: • Set the Tolerance Offset. This changes the softness range by the same amount for every active channel. • Click the Add Tolerance picker , and then pick a point in the image, or click and drag the cursor over the image to sample a range of pixels. CTRL-click and drag to sample a rectangular area. The tolerance range extends to include the color of the pixels you sampled. • Click the Remove Tolerance picker , and then pick a point in the image, or click and drag the cursor over the image to sample a range of pixels. CTRL-click and drag to sample a rectangular area. The tolerance range shrinks to exclude the pixel you picked. • Set the tolerance by channel. You can set the tolerance on either side of the range. • Drag the cyan line in the color bar. Using the Plot Tool You can plot the color value for any pixel in the key color bars. You can then adjust the tolerance or softness range so that the pixel falls within one of the ranges. To plot a pixel's color values: 1. Click the Plot picker. 2. Sample a pixel in the image. A red bar appears in each of the color bars showing the color value of the pixel that you sampled. Note: You can change the color of the plot bar in the Setup controls. bringing in a matte (for example a black and white logo) as a key-in source. You can also use the Luma mode to adjust a matte that has already been rendered. Load the matte as the key-in clip then adjust it using the Key controls in Luma mode. To create a key by setting the luminance: 1. In the Key controls, select Luma from the Keyer Mode list. In the front clip, black is transparent, and white is opaque. 2. Adjust the tolerance to key out more of the blacks. Increasing tolerance increases the range of pixels that will be completely transparent. Tolerance values are expressed in percentage. A value of 100 makes the front image completely transparent. 3. Set the softness. By default, softness is set to 100. Increasing softness makes the image more transparent. When softness is 0, only pixels that fall within the tolerance range are keyed out. The matte is black and white with no grays. Adjusting the Matte The keying process extracts colors from the front image and generates a matte. You can adjust the matte using the histogram, Lift and Gain controls, or you can modify the edge of the matte using the Shrink, Erode or Blur tools. To access the Matte controls: In the Keyer Controls panel, click the Matte button under the Key button. Extracting a Key Based on Luminance You can create a key using only the Luminance channel. This technique is most often used for shots filmed against a black background, or when Using the Histogram The histogram displays the distribution of luminance values within the matte. 622

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Keying
23
622
2.
Do one of the following:
Set the Tolerance Offset. This changes the
softness range by the same amount for every
active channel.
Click the Add Tolerance picker
, and then
pick a point in the image, or click and drag the
cursor over the image to sample a range of pixels.
C
TRL
-click and drag to sample a rectangular area.
The tolerance range extends to include the color
of the pixels you sampled.
Click the Remove Tolerance picker
, and
then pick a point in the image, or click and drag
the cursor over the image to sample a range of
pixels.
C
TRL
-click and drag to sample a
rectangular area. The tolerance range shrinks to
exclude the pixel you picked.
Set the tolerance by channel. You can set the
tolerance on either side of the range.
Drag the cyan line in the color bar.
Using the Plot Tool
You can plot the color value for any pixel in the key
color bars. You can then adjust the tolerance or
softness range so that the pixel falls within one of the
ranges.
To plot a pixel’s color values:
1.
Click the Plot picker.
2.
Sample a pixel in the image.
A red bar appears in each of the color bars
showing the color value of the pixel that you
sampled.
Note:
You can change the color of the plot bar in
the Setup controls.
Extracting a Key Based on Luminance
You can create a key using only the Luminance
channel. This technique is most often used for shots
filmed against a black background, or when
bringing in a matte (for example a black and white
logo) as a key-in source.
You can also use the Luma mode to adjust a matte
that has already been rendered. Load the matte as the
key-in clip then adjust it using the Key controls in
Luma mode.
To create a key by setting the luminance:
1.
In the Key controls, select Luma from the Keyer
Mode list.
In the front clip, black is transparent, and white is
opaque.
2.
Adjust the tolerance to key out more of the blacks.
Increasing tolerance increases the range of pixels
that will be completely transparent. Tolerance
values are expressed in percentage. A value of 100
makes the front image completely transparent.
3.
Set the softness. By default, softness is set to 100.
Increasing softness makes the image more
transparent. When softness is 0, only pixels that
fall within the tolerance range are keyed out. The
matte is black and white with no grays.
Adjusting the Matte
The keying process extracts colors from the front
image and generates a matte. You can adjust the
matte using the histogram, Lift and Gain controls, or
you can modify the edge of the matte using the
Shrink, Erode or Blur tools.
To access the Matte controls:
In the Keyer Controls panel, click the Matte button
under the Key button.
Using the Histogram
The histogram displays the distribution of
luminance values within the matte.