Review/Statistics/itkHistogramToProbabilityImageFilter.h

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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkHistogramToProbabilityImageFilter.h,v $
  Language:  C++
  Date:      $Date: 2010-05-28 01:35:22 $
  Version:   $Revision: 1.1 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/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 notices for more information.

=========================================================================*/
#ifndef __itkHistogramToProbabilityImageFilter_h
#define __itkHistogramToProbabilityImageFilter_h

#include "itkHistogramToImageFilter.h"

namespace itk
{
  
namespace Function {  
template< class TInput, class TOutput=float >
class HistogramProbabilityFunction
{
public:
  
  //Probability function = Number of occurances in each bin /
  //   Total Number of occurances. 
  //
  // Returns pixels of float.. 
  typedef  TOutput  OutputPixelType;
  
  
  HistogramProbabilityFunction(): 
      m_TotalFrequency(1) {}

  ~HistogramProbabilityFunction() {};

  inline OutputPixelType operator()( const TInput & A ) const
    {
    return static_cast<OutputPixelType>( static_cast<OutputPixelType>(A) / 
        static_cast<OutputPixelType>(m_TotalFrequency) );
    }

  void SetTotalFrequency( unsigned long n ) 
    {
    m_TotalFrequency = n;
    }
  
  unsigned long GetTotalFrequency( ) const 
    {
    return m_TotalFrequency;
    }

private:
  unsigned long  m_TotalFrequency;
}; 
}

template <class THistogram, unsigned int NDimensions, class TOutputPixel=float >
class ITK_EXPORT HistogramToProbabilityImageFilter :
  public HistogramToImageFilter< THistogram, NDimensions,
  Function::HistogramProbabilityFunction< unsigned long, TOutputPixel > > 
{
public:
  
  typedef HistogramToProbabilityImageFilter Self;

  typedef HistogramToImageFilter< THistogram, NDimensions,
    Function::HistogramProbabilityFunction< unsigned long, TOutputPixel> >
                                            Superclass;

  typedef SmartPointer<Self>                Pointer;
  typedef SmartPointer<const Self>          ConstPointer;
  
  itkTypeMacro( HistogramToProbabilityImageFilter, HistogramToImageFilter );

  itkNewMacro(Self);

protected:
  HistogramToProbabilityImageFilter() {}
  virtual ~HistogramToProbabilityImageFilter() {}
  
private:
  HistogramToProbabilityImageFilter(const Self&); //purposely not implemented
  void operator=(const Self&); //purposely not implemented

};

} // end namespace itk

#endif