Using Compound Alpha Arithmetic

Use Compound Alpha Arithmetic to set the alpha channel of a layer using another image in the workspace.

To apply a Compound Alpha Arithmetic filter:

1. Select the layer.
2. Choose Operators | Channel | Compound Alpha Arithmetic.

The Compound Alpha Arithmetic Controls panel appears.

The Compound Alpha Arithmetic Controls panel contains the following elements.

Operator

Specifies which mathematical operation is applied to the alpha channel. For a complete list of options, see Operator List Options.

Layer

Specifies the operator to be used as the source for the mathematical operations. When you click this button, the Operator Picker dialog appears allowing you to specify an operator.

To remove an operator, click the Layer button, and then click the None button in the Operator Picker dialog.

Input Channel

Specifies which channel of the source layer is used. Available channels include: Luminance, Red, Green, Blue, Alpha, Hue, Saturation, and Value.

Undefined Areas

Specifies the color used to fill in the blank (0% opacity) areas of the image. Click the Pick button to select a color from the screen, or click the color box to choose a color from the color picker.

Blend

Specifies the percentage amount for which the channel effect is visible over the original layer. Values below 100% allow you to see the original layer.