contrib/brl/bseg/brip/brip_blobwise_mutual

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00001 // This is brl/bseg/brip/brip_blobwise_mutual_info.h
00002 #ifndef brip_blobwise_mutual_info_h_
00003 #define brip_blobwise_mutual_info_h_
00004 //:
00005 // \file
00006 // \brief Calculate patchwise mutual info between two images
00007 // \author Matt Leotta
00008 //
00009 
00010 #include <vil/vil_image_view.h>
00011 #include <vcl_vector.h>
00012 #include <vcl_cmath.h>
00013 #include <vnl/vnl_math.h>
00014 
00015 //: Calculate the Mutual Information between the images.
00016 template<class T>
00017 void brip_blobwise_mutual_info ( const vil_image_view<T>& img1,
00018                                  const vil_image_view<T>& img2,
00019                                  const vil_image_view<T>& weights,
00020                                  const vil_image_view<bool>& mask,
00021                                        vil_image_view<T>& mi_img ); 
00022 
00023 
00024 template<class T>
00025 void brip_blobwise_kl_div( const vil_image_view<T>& img1,
00026                            const vil_image_view<T>& img2,
00027                            const vil_image_view<bool>& mask,
00028                                  vil_image_view<T>& mi_img ); 
00029                                  
00030 //: calculates the kl divergeance D_kl ( P || Q ); 
00031 inline
00032 double brip_hist_kl_div(const vcl_vector<double>& P, double magP, 
00033                         const vcl_vector<double>& Q, double magQ)
00034 {
00035   double kl = 0.0;
00036   for (unsigned int i=0; i<P.size(); ++i) {
00037     double probP = P[i]/magP; 
00038     double probQ = Q[i]/magQ; 
00039     if (probP==0 || probQ==0) continue; 
00040     
00041     kl += probP * vcl_log( probP / probQ ); 
00042   }
00043   return  kl/vnl_math::ln2; // divide by ln(2) to convert this measure to base 2
00044 }
00045 
00046 #endif // brip_blobwise_mutual_info_h_