/*=========================================================================

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkImageButterworthLowPass.h,v $

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
// .NAME vtkImageButterworthLowPass - Frequency domain Low pass.
// .SECTION Description
// This filter only works on an image after it has been converted to
// frequency domain by a vtkImageFFT filter.  A vtkImageRFFT filter
// can be used to convert the output back into the spatial domain.
// vtkImageButterworthLowPass  the high frequency components are
// attenuated.  Input and output are in doubles, with two components
// (complex numbers).
// out(i, j) = (1 + pow(CutOff/Freq(i,j), 2*Order));

// .SECTION See Also
// vtkImageButterworthHighPass vtkImageFFT vtkImageRFFT

#ifndef __vtkImageButterworthLowPass_h
#define __vtkImageButterworthLowPass_h


#include "vtkThreadedImageAlgorithm.h"

class VTK_IMAGING_EXPORT vtkImageButterworthLowPass : public vtkThreadedImageAlgorithm
{
public:
  static vtkImageButterworthLowPass *New();
  vtkTypeRevisionMacro(vtkImageButterworthLowPass,vtkThreadedImageAlgorithm);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Set/Get the cutoff frequency for each axis.
  // The values are specified in the order X, Y, Z, Time.
  // Units: Cycles per world unit (as defined by the data spacing).
  vtkSetVector3Macro(CutOff,double);
  void SetCutOff(double v) {this->SetCutOff(v, v, v);}
  void SetXCutOff(double v);
  void SetYCutOff(double v);
  void SetZCutOff(double v);
  vtkGetVector3Macro(CutOff,double);
  double GetXCutOff() {return this->CutOff[0];}
  double GetYCutOff() {return this->CutOff[1];}
  double GetZCutOff() {return this->CutOff[2];}

  // Description:
  // The order determines sharpness of the cutoff curve.
  vtkSetMacro(Order, int);
  vtkGetMacro(Order, int);
  
  
protected:
  vtkImageButterworthLowPass();
  ~vtkImageButterworthLowPass() {};

  int Order;
  double CutOff[3];
  
  void ThreadedRequestData( vtkInformation *request,
                            vtkInformationVector **inputVector,
                            vtkInformationVector *outputVector,
                            vtkImageData ***inData, vtkImageData **outData,
                            int outExt[6], int id);
private:
  vtkImageButterworthLowPass(const vtkImageButterworthLowPass&);  // Not implemented.
  void operator=(const vtkImageButterworthLowPass&);  // Not implemented.
};

#endif



