ITK  4.1.0
Insight Segmentation and Registration Toolkit
itkHistogramToEntropyImageFilter.h
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00001 /*=========================================================================
00002  *
00003  *  Copyright Insight Software Consortium
00004  *
00005  *  Licensed under the Apache License, Version 2.0 (the "License");
00006  *  you may not use this file except in compliance with the License.
00007  *  You may obtain a copy of the License at
00008  *
00009  *         http://www.apache.org/licenses/LICENSE-2.0.txt
00010  *
00011  *  Unless required by applicable law or agreed to in writing, software
00012  *  distributed under the License is distributed on an "AS IS" BASIS,
00013  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00014  *  See the License for the specific language governing permissions and
00015  *  limitations under the License.
00016  *
00017  *=========================================================================*/
00018 #ifndef __itkHistogramToEntropyImageFilter_h
00019 #define __itkHistogramToEntropyImageFilter_h
00020 
00021 #include "itkHistogramToImageFilter.h"
00022 
00023 namespace itk
00024 {
00052 namespace Function
00053 {
00054 template< class TInput, class TOutput = double >
00055 class HistogramEntropyFunction
00056 {
00057 public:
00058 
00059   //Probability function = Number of occurances in each bin /
00060   //   Total Number of occurances.
00061   //
00062   // Returns pixels of float..
00063   typedef  TOutput OutputPixelType;
00064 
00065   HistogramEntropyFunction():
00066     m_TotalFrequency(1) {}
00067 
00068   ~HistogramEntropyFunction() {}
00069 
00070   inline OutputPixelType operator()(const TInput & A) const
00071   {
00072     if ( A )
00073       {
00074       const double p = static_cast< OutputPixelType >( A )
00075                        / static_cast< OutputPixelType >( m_TotalFrequency );
00076       return static_cast< OutputPixelType >( ( -1 ) * p * vcl_log(p) / vcl_log(2.0) );
00077       }
00078     else
00079       {
00080       const double p = static_cast< OutputPixelType >( A + 1 )
00081                        / static_cast< OutputPixelType >( m_TotalFrequency );
00082       return static_cast< OutputPixelType >( ( -1 ) * p * vcl_log(p) / vcl_log(2.0) );
00083       }
00084   }
00085 
00086   void SetTotalFrequency(const SizeValueType n)
00087   {
00088     m_TotalFrequency = n;
00089   }
00090 
00091   SizeValueType GetTotalFrequency() const
00092   {
00093     return m_TotalFrequency;
00094   }
00095 
00096 private:
00097   SizeValueType m_TotalFrequency;
00098 };
00099 }
00100 
00101 template< class THistogram, class TImage=Image< double, 3> >
00102 class ITK_EXPORT HistogramToEntropyImageFilter:
00103   public HistogramToImageFilter< THistogram, TImage,
00104                                  Function::HistogramEntropyFunction< SizeValueType, typename TImage::PixelType > >
00105 {
00106 public:
00107 
00109   typedef HistogramToEntropyImageFilter Self;
00110 
00112   typedef HistogramToImageFilter< THistogram, TImage,
00113                                  Function::HistogramEntropyFunction< SizeValueType, typename TImage::PixelType > >
00114   Superclass;
00115 
00116   typedef SmartPointer< Self >       Pointer;
00117   typedef SmartPointer< const Self > ConstPointer;
00118 
00120   itkTypeMacro(HistogramToEntropyImageFilter, HistogramToImageFilter);
00121 
00123   itkNewMacro(Self);
00124 protected:
00125   HistogramToEntropyImageFilter() {}
00126   virtual ~HistogramToEntropyImageFilter() {}
00127 private:
00128   HistogramToEntropyImageFilter(const Self &); //purposely not implemented
00129   void operator=(const Self &);                //purposely not implemented
00130 };
00131 } // end namespace itk
00133 
00134 #endif
00135