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

  Program:   Visualization Toolkit
  Module:    vtkImageButterworthLowPass.h

  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.

=========================================================================*/
/**
 * @class   vtkImageButterworthLowPass
 * @brief   Frequency domain Low pass.
 *
 * 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));
 *
 * @sa
 * vtkImageButterworthHighPass vtkImageFFT vtkImageRFFT
*/

#ifndef vtkImageButterworthLowPass_h
#define vtkImageButterworthLowPass_h


#include "vtkImagingFourierModule.h" // For export macro
#include "vtkThreadedImageAlgorithm.h"

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

  //@{
  /**
   * 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];}
  //@}

  //@{
  /**
   * The order determines sharpness of the cutoff curve.
   */
  vtkSetMacro(Order, int);
  vtkGetMacro(Order, int);
  //@}


protected:
  vtkImageButterworthLowPass();
  ~vtkImageButterworthLowPass() override {}

  int Order;
  double CutOff[3];

  void ThreadedRequestData( vtkInformation *request,
                            vtkInformationVector **inputVector,
                            vtkInformationVector *outputVector,
                            vtkImageData ***inData, vtkImageData **outData,
                            int outExt[6], int id) override;
private:
  vtkImageButterworthLowPass(const vtkImageButterworthLowPass&) = delete;
  void operator=(const vtkImageButterworthLowPass&) = delete;
};

#endif
