Key out a luminance value with the luma key effect, Spill suppressor effect – Adobe After Effects CS4 User Manual
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USING AFTER EFFECTS CS4
Effects and animation presets
Last updated 12/21/2009
White background of original (upper-left and lower-left) is removed using Luma Key and composited over underlying layer (lower-right).
More Help topics
Keying introduction and resources
Key out a luminance value with the Luma Key effect
1
Select the layer that you want to make partially transparent, and choose Effect > Keying > Luma Key.
2
Select a Key Type to specify the range to be keyed out.
3
Drag the Threshold slider in the Effect Controls panel to set the luminance value you want the matte to be based on.
4
Drag the Tolerance slider to specify the range of values to be keyed out. Lower values key out a smaller range of
values near the threshold. Higher values key out a wider range of values.
5
Drag the Edge Thin slider to adjust the width of the border of the keyed area. Positive values make the mask grow,
increasing the transparent area. Negative values shrink the mask.
6
Drag the Edge Feather slider to specify the softness of the edge. Higher values create a softer edge but take longer
to render.
Spill Suppressor effect
The Spill Suppressor effect removes traces of the key color from an image with a screen that’s already been keyed out.
Typically, the Spill Suppressor is used to remove key color spills from the edges of an image. Spills are caused by light
reflecting off the screen and onto the subject.
If you’re not satisfied with the results from using the Spill Suppressor, try applying the Hue/Saturation effect to a layer
after keying, and then decrease the saturation value to de-emphasize the key color. (See “
This effect works with 8-bpc and 16-bpc color.