Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 445

Select the Black eyedropper, and then click inside the matte thumbnail on the lightest area of black to specify
5
transparent regions. The transparency values in the thumbnail and Composition panel are adjusted.
Select the White eyedropper, and then click inside the matte thumbnail on the darkest area of white to specify
6
opaque regions. The opaque values in the thumbnail and the Composition panel are adjusted.
To produce the best possible key, make the black and white areas as different as you can so that the image retains as
many shades of gray as possible.
7 Select a matching accuracy from the Color Matching Accuracy menu. Choose Faster unless you use a screen that
isn't a primary color (red, blue, or yellow). For those screens, choose More Accurate, which increases rendering time
but produces better results.
If you need to further adjust transparency values, repeat steps 5 and 6 for one or both of the partial mattes. Click
8
the Partial Matte B button or the Partial Matte A button to select a partial matte, and then repeat the steps.
Adjust transparency values for each partial matte and for the final matte by dragging one or more of the following
9
sliders in the Matte Controls section:
• Black sliders adjust the transparency levels of each matte. You can adjust the same levels using the Black
eyedropper.
• White sliders adjust the opaque levels of each matte. You can adjust the same levels using the White eyedropper.
• Gamma sliders control how closely the transparency values follow a linear progression. At a value of 1 (the
default), the progression is linear. Other values produce nonlinear progressions for particular adjustments or
visual effects.
When adjusting individual mattes, choose from the View menu to compare the mattes with and without adjust-
10
ments:
• Choose Uncorrected to view a matte without adjustments.
• Choose Corrected to view a matte with all adjustments.
Before closing the Effect Controls panel, select Final Output from the View menu. Final Output must be selected
11
for After Effects to render the transparency.
To remove traces of reflected key color from the image, apply Spill Suppressor using Better For Color Accuracy. If the
image still has a lot of color, apply the Simple Choker or Matte Choker effect.
Color Key effect
The Color Key effect keys out all image pixels that are similar to a specified key color. This effect modifies only the
alpha channel of a layer.
This effect works with 8-bpc and 16-bpc color.
See also
"Keying overview" on page 268
"Matte Choker effect" on page 448
"Simple Choker effect" on page 448
Key out a single color with the Color Key effect
Select the layer.
1
2 Choose Effect > Keying > Color Key.
AFTER EFFECTS CS3 439
User Guide