itkSigmoidImageFilter.h

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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkSigmoidImageFilter.h,v $
  Language:  C++
  Date:      $Date: 2009-04-01 14:36:31 $
  Version:   $Revision: 1.17 $

  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 __itkSigmoidImageFilter_h
#define __itkSigmoidImageFilter_h

#include "itkUnaryFunctorImageFilter.h"

namespace itk
{
  
namespace Function {  
template< class TInput, class TOutput>
class Sigmoid
{
public:
  Sigmoid() 
    { 
    m_Alpha = 1.0; 
    m_Beta =  0.0; 
    m_OutputMinimum = NumericTraits< TOutput >::min();
    m_OutputMaximum = NumericTraits< TOutput >::max();
    }
  ~Sigmoid() {};
  bool operator!=( const Sigmoid & other ) const
    {
    if( m_Alpha != other.m_Alpha ||
        m_Beta != other.m_Beta ||
        m_OutputMaximum != other.m_OutputMaximum    ||
        m_OutputMinimum != other.m_OutputMinimum  )
      {
      return true;
      }
    return false;
    }
  bool operator==( const Sigmoid & other ) const
    {
    return !(*this != other);
    }

  inline TOutput operator()( const TInput & A ) const
    {
    const double x = ( static_cast<double>(A) - m_Beta ) / m_Alpha;
    const double e = 1.0 / ( 1.0 + vcl_exp(- x ) );
    const double v = 
      (m_OutputMaximum - m_OutputMinimum ) * e + m_OutputMinimum;
    return static_cast<TOutput>( v );
    }
  void SetAlpha( double alpha )
    {
    m_Alpha = alpha;
    }
  void SetBeta( double beta )
    {
    m_Beta = beta;
    }
  double GetAlpha() const
    {
    return m_Alpha;
    }
  double GetBeta() const
    {
    return m_Beta;
    }
  void SetOutputMinimum( TOutput min )
    {
    m_OutputMinimum = min;
    }
  void SetOutputMaximum( TOutput max )
    {
    m_OutputMaximum = max;
    }
  TOutput GetOutputMinimum() const
    {
    return m_OutputMinimum;
    }
  TOutput GetOutputMaximum() const
    {
    return m_OutputMaximum;
    }

private:
  double  m_Alpha;
  double  m_Beta;
  TOutput m_OutputMinimum;
  TOutput m_OutputMaximum;
}; 
}


template <class TInputImage, class TOutputImage>
class ITK_EXPORT SigmoidImageFilter :
    public
UnaryFunctorImageFilter<TInputImage,TOutputImage, 
                        Function::Sigmoid< 
  typename TInputImage::PixelType, 
  typename TOutputImage::PixelType>   >
{
public:
  typedef SigmoidImageFilter                                Self;
  typedef UnaryFunctorImageFilter<
    TInputImage,TOutputImage, 
    Function::Sigmoid< typename TInputImage::PixelType, 
                       typename TOutputImage::PixelType> >  Superclass;
  typedef SmartPointer<Self>                                Pointer;
  typedef SmartPointer<const Self>                          ConstPointer;

  typedef typename TOutputImage::PixelType OutputPixelType;

  itkNewMacro(Self);

  itkTypeMacro( SigmoidImageFilter, UnaryFunctorImageFilter );

  void SetAlpha( double alpha )
    {
    if( alpha == this->GetFunctor().GetAlpha() ) 
      {
      return;
      }
    this->GetFunctor().SetAlpha( alpha );
    this->Modified();
    }

  void SetBeta( double beta )
    {
    if( beta == this->GetFunctor().GetBeta() ) 
      {
      return;
      }
    this->GetFunctor().SetBeta( beta );
    this->Modified();
    }

  void SetOutputMinimum( OutputPixelType min )
    {
    if( min == this->GetFunctor().GetOutputMinimum() ) 
      {
      return;
      }
    this->GetFunctor().SetOutputMinimum( min );
    this->Modified();
    }

  void SetOutputMaximum( OutputPixelType max )
    {
    if( max == this->GetFunctor().GetOutputMaximum() ) 
      {
      return;
      }
    this->GetFunctor().SetOutputMaximum( max );
    this->Modified();
    }

#ifdef ITK_USE_CONCEPT_CHECKING

  itkConceptMacro(InputConvertibleToDoubleCheck,
    (Concept::Convertible<typename TInputImage::PixelType, double>));
  itkConceptMacro(OutputAdditiveOperatorsCheck,
    (Concept::AdditiveOperators<OutputPixelType>));
  itkConceptMacro(DoubleConvertibleToOutputCheck,
    (Concept::Convertible<double, OutputPixelType>));
  itkConceptMacro(OutputTimesDoubleCheck,
    (Concept::MultiplyOperator<OutputPixelType, double>));
  itkConceptMacro(OutputDoubleAdditiveOperatorsCheck,
    (Concept::AdditiveOperators<OutputPixelType, OutputPixelType, double>));

#endif

protected:
  SigmoidImageFilter() {}
  virtual ~SigmoidImageFilter() {}

private:
  SigmoidImageFilter(const Self&); //purposely not implemented
  void operator=(const Self&); //purposely not implemented

};

} // end namespace itk


#endif