[vtk-developers] vtkImageButterworth filters

[John Biddiscombe]

I see at the top of the .h files for Low (+High)pass filters that

 out(i, j) = (1 + pow(CutOff/Freq(i,j), 2*Order));

But in the cxx file the implementation is
 sum0 = 1.0 / (1.0 + pow(sum0, (float)this->Order));

The factor of two is absent from the order in the cxx

Most texts use

H(W) = 1
       -----------
      (1+(F/Fc)^2n)

As opposed to just n (n being order)

This looks like a typo/mistake to me. Have I missed anything?

Thanks

JB