    idealRfft = vtkImageRFFT()
    idealRfft.SetInputConnection(idealHighPass.GetOutputPort())

    idealReal = vtkImageExtractComponents()
    idealReal.SetInputConnection(idealRfft.GetOutputPort())
    idealReal.SetComponents(0)
--
    butterworthRfft = vtkImageRFFT()
    butterworthRfft.SetInputConnection(butterworthHighPass.GetOutputPort())

    butterworthReal = vtkImageExtractComponents()
    butterworthReal.SetInputConnection(butterworthRfft.GetOutputPort())
    butterworthReal.SetComponents(0)
