Zero artifact at a given spatial frequency

The first is very simple to arrange. We just need to choose the coefficients so that the kernel has a zero at the value of a which corresponds to the frequency at which we wish to have zero artifact. 

Suppose that we want to have zero artifact at u = coq- Then we require that Zc(sin(7rwo/2)) = 0 

Note that this value will be greater than 1, tending to 1 as uj — 0. Also it will never be greater than 2 for cuq 1/2. 

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