Foundation > Image Processing Filters > IlvBitmapFilter: The Image Processing Class > The IlvComposeFilter Class
 
The IlvComposeFilter Class
The IlvComposeFilter class lets you perform the combination of the two input images pixel-wise in image space using one of the Porter-Duff compositing operations: over, in, atop, out, xor. Additionally, a component-wise arithmetic operation (with the result clamped between [0..1]) can be applied. You have a choice of these six operators for the compositing, shown in Compositing Operators.
The resulting color is given by the formula:
Cresult = Fa * Ca + Fb * Cb
where:
*Fa and Fb depend on the operator as shown in Compositing Operators.
*Ca is the color from the first image, and Cb is the color from the second image.
*In the table, Aa is the alpha value from the first image and Ab is the alpha value from the second image.
Compositing Operators 
Operator
Operation
over
Fa = 1, Fb = 1 - Aa
in
Fa = Ab, Fb = 0
out
Fa = 1 - Ab, Fb = 0
atop
Fa = Ab, Fb = 1 - Aa
xor
1 - Ab, Fb = a - Aa
arithmetic
Cresult = k1 * Ca * Cb + k2 * Ca + k3 * Ca * Cb + k4

Version 6.3
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