To Use The Color Difference Key Effect; To Preserve A Color After Applying Linear Color Key - Adobe AFTER EFFECTS 7.0 Manual

To preserve a color after applying Linear Color Key

1 In the Effect Controls panel or Timeline panel, turn off any current instances of keys or matte effects by
deselecting the Effect option to the left of the key name or tool name. This displays the original image in the Compo-
sition panel so that you can select a color to preserve.
Choose Effect > Keying > Linear Color Key. A second set of Linear Color Key controls appears in the Effect
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Controls panel below the first set.
3 In the Effect Controls panel, choose Keep Colors from the Key Operation menu.
Select the color you want to keep.
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In the first application of the Linear Color Key effect, choose Final Output from the View menu in the Effect
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Controls panel, and then turn other instances of the Linear Color Key effect back on to examine the transparency.
You may need to adjust colors or reapply the key a third time to get the results you need.
See also
"Linear Color Key effect" on page 465

To use the Color Difference Key effect

Select the layer you want to make transparent, and then choose Effect > Keying > Color Difference Key.
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Note: To use any of the eyedroppers in the Layer panel, choose Color Difference Key from the View pop-up menu in the
Layer panel.
In the Effect Controls panel, choose Matte Corrected from the View menu. To view and compare the source
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image, both partial mattes, and the final matte at the same time, choose [A, B, Matte] Corrected, Final from the View
menu. Other views available in the View menu are described in step 10.
3 Select the appropriate key color: To key out a bluescreen, use the default blue color. To key out a non-blue screen,
select a key color in one of the following ways:
•
Thumbnail eyedropper: Select and then click in the Composition panel or the original thumbnail image on an
appropriate area.
•
Key Color eyedropper: Select and then click in the Composition or Layer panel on an appropriate area.
•
Key Color swatch: Click to select a color from the specified color space.
Note: The eyedropper tools move the sliders accordingly. Use the sliders in step 9 to fine-tune the keying results.
4 Click the matte button to display the final combined matte in the matte thumbnail.
Select the Black eyedropper, and then click inside the matte thumbnail on the lightest area of black to specify
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transparent regions. The transparency values in the thumbnail and Composition panel are adjusted.
6 Select the White eyedropper, and then click inside the matte thumbnail on the darkest area of white to specify
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.
Select a matching accuracy from the Color Matching Accuracy menu. Choose Faster unless you are using a screen
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that is not a primary color, such as orange. 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
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the Partial Matte B button or the Partial Matte A button to select a partial matte, and then repeat the steps.
ADOBE AFTER EFFECTS 7.0 273
User Guide