This filter primitive performs the combination of 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.
The arithmetic operation is useful for combining the output from the
result = k1*i1*i2 + k2*i1 + k3*i2 + k4
i2indicate the corresponding pixel channel values of the input image, which map to
k1, k2, k3and
k4indicate the values of the attributes with the same name