Color Key

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. The layer's quality setting does not affect Color Key.


A non-standard green screen (left) and the background (center) are combined with Color Key (right).

When you key out a color value in a layer, that color or range of colors becomes transparent for the entire layer. Control the range of transparent colors by adjusting the tolerance level. You can also feather the edges of the transparent area to create a smooth transition between the transparent and opaque areas.

To key out a single color:

1. Select the layer.
2. Choose Effect > Keying > Color Key.
3. In the Effect Controls window, specify a key color in one of two ways:
• Click the Key Color swatch to open the Color dialog box and specify a color.
• Click the eyedropper, and then click a color on the screen.
4. Drag the Color Tolerance slider to specify the range of color to key out. Lower values key out a smaller range of colors near the key color. Higher values key out a wider range of color.
5. Drag the Edge Thin slider to adjust the width of the keyed area's border. Positive values enlarge the mask, increasing the transparent area. Negative values shrink the mask, decreasing the transparent area.
6. Drag the Edge Feather slider to specify the softness of the edge. Higher values create a softer edge but take longer to render.