diff --git a/modules/imgproc/doc/histograms.rst b/modules/imgproc/doc/histograms.rst index 91199f3781..5ebf168611 100644 --- a/modules/imgproc/doc/histograms.rst +++ b/modules/imgproc/doc/histograms.rst @@ -181,6 +181,8 @@ Compares two histograms. * **CV_COMP_HELLINGER** Synonym for ``CV_COMP_BHATTACHARYYA`` + * **CV_COMP_KL_DIV** Kullback-Leibler divergence + The functions ``compareHist`` compare two dense or two sparse histograms using the specified method: * Correlation (``method=CV_COMP_CORREL``) @@ -224,6 +226,12 @@ The functions ``compareHist`` compare two dense or two sparse histograms using t d(H_1,H_2) = \sqrt{1 - \frac{1}{\sqrt{\bar{H_1} \bar{H_2} N^2}} \sum_I \sqrt{H_1(I) \cdot H_2(I)}} +* Kullback-Leibler divergence (``method=CV_COMP_KL_DIV``). + + .. math:: + + d(H_1,H_2) = \sum _I H_1(I) \log \left(\frac{H_1(I)}{H_2(I)}\right) + The function returns :math:`d(H_1, H_2)` . diff --git a/modules/imgproc/include/opencv2/imgproc.hpp b/modules/imgproc/include/opencv2/imgproc.hpp index 7928ae0fe8..76d65c2802 100644 --- a/modules/imgproc/include/opencv2/imgproc.hpp +++ b/modules/imgproc/include/opencv2/imgproc.hpp @@ -204,7 +204,8 @@ enum { HISTCMP_CORREL = 0, HISTCMP_INTERSECT = 2, HISTCMP_BHATTACHARYYA = 3, HISTCMP_HELLINGER = HISTCMP_BHATTACHARYYA, - HISTCMP_CHISQR_ALT = 4 + HISTCMP_CHISQR_ALT = 4, + HISTCMP_KL_DIV = 5 }; //! the color conversion code diff --git a/modules/imgproc/include/opencv2/imgproc/types_c.h b/modules/imgproc/include/opencv2/imgproc/types_c.h index dd0d8b8a6e..de8fb62038 100644 --- a/modules/imgproc/include/opencv2/imgproc/types_c.h +++ b/modules/imgproc/include/opencv2/imgproc/types_c.h @@ -509,7 +509,8 @@ enum CV_COMP_INTERSECT =2, CV_COMP_BHATTACHARYYA =3, CV_COMP_HELLINGER =CV_COMP_BHATTACHARYYA, - CV_COMP_CHISQR_ALT =4 + CV_COMP_CHISQR_ALT =4, + CV_COMP_KL_DIV =5 }; /* Mask size for distance transform */ diff --git a/modules/imgproc/src/histogram.cpp b/modules/imgproc/src/histogram.cpp index 441d2226b8..b38ddcad0c 100644 --- a/modules/imgproc/src/histogram.cpp +++ b/modules/imgproc/src/histogram.cpp @@ -2325,6 +2325,21 @@ double cv::compareHist( InputArray _H1, InputArray _H2, int method ) s2 += b; } } + else if( method == CV_COMP_KL_DIV ) + { + for( j = 0; j < len; j++ ) + { + double p = h1[j]; + double q = h2[j]; + if( fabs(p) <= DBL_EPSILON ) { + continue; + } + if( fabs(q) <= DBL_EPSILON ) { + q = 1e-10; + } + result += p * std::log( p / q ); + } + } else CV_Error( CV_StsBadArg, "Unknown comparison method" ); } @@ -2360,7 +2375,7 @@ double cv::compareHist( const SparseMat& H1, const SparseMat& H2, int method ) CV_Assert( H1.size(i) == H2.size(i) ); const SparseMat *PH1 = &H1, *PH2 = &H2; - if( PH1->nzcount() > PH2->nzcount() && method != CV_COMP_CHISQR && method != CV_COMP_CHISQR_ALT) + if( PH1->nzcount() > PH2->nzcount() && method != CV_COMP_CHISQR && method != CV_COMP_CHISQR_ALT && method != CV_COMP_KL_DIV ) std::swap(PH1, PH2); SparseMatConstIterator it = PH1->begin(); @@ -2440,6 +2455,18 @@ double cv::compareHist( const SparseMat& H1, const SparseMat& H2, int method ) s1 = fabs(s1) > FLT_EPSILON ? 1./std::sqrt(s1) : 1.; result = std::sqrt(std::max(1. - result*s1, 0.)); } + else if( method == CV_COMP_KL_DIV ) + { + for( i = 0; i < N1; i++, ++it ) + { + double v1 = it.value(); + const SparseMat::Node* node = it.node(); + double v2 = PH2->value(node->idx, (size_t*)&node->hashval); + if( !v2 ) + v2 = 1e-10; + result += v1 * std::log( v1 / v2 ); + } + } else CV_Error( CV_StsBadArg, "Unknown comparison method" ); @@ -2785,7 +2812,7 @@ cvCompareHist( const CvHistogram* hist1, CvSparseMatIterator iterator; CvSparseNode *node1, *node2; - if( mat1->heap->active_count > mat2->heap->active_count && method != CV_COMP_CHISQR && method != CV_COMP_CHISQR_ALT) + if( mat1->heap->active_count > mat2->heap->active_count && method != CV_COMP_CHISQR && method != CV_COMP_CHISQR_ALT && method != CV_COMP_KL_DIV ) { CvSparseMat* t; CV_SWAP( mat1, mat2, t ); @@ -2887,6 +2914,13 @@ cvCompareHist( const CvHistogram* hist1, result = 1. - result*s1; result = sqrt(MAX(result,0.)); } + else if( method == CV_COMP_KL_DIV ) + { + cv::SparseMat sH1, sH2; + ((const CvSparseMat*)hist1->bins)->copyToSparseMat(sH1); + ((const CvSparseMat*)hist2->bins)->copyToSparseMat(sH2); + result = cv::compareHist( sH1, sH2, CV_COMP_KL_DIV ); + } else CV_Error( CV_StsBadArg, "Unknown comparison method" ); diff --git a/modules/imgproc/test/test_histograms.cpp b/modules/imgproc/test/test_histograms.cpp index 19ccc656b5..e9db6fcde0 100644 --- a/modules/imgproc/test/test_histograms.cpp +++ b/modules/imgproc/test/test_histograms.cpp @@ -948,7 +948,7 @@ int CV_ThreshHistTest::validate_test_results( int /*test_case_idx*/ ) class CV_CompareHistTest : public CV_BaseHistTest { public: - enum { MAX_METHOD = 5 }; + enum { MAX_METHOD = 6 }; CV_CompareHistTest(); protected: @@ -1021,6 +1021,13 @@ int CV_CompareHistTest::validate_test_results( int /*test_case_idx*/ ) sq0 += v0*v0; sq1 += v1*v1; result0[CV_COMP_BHATTACHARYYA] += sqrt(v0*v1); + { + if( fabs(v0) <= DBL_EPSILON ) + continue; + if( fabs(v1) <= DBL_EPSILON ) + v1 = 1e-10; + result0[CV_COMP_KL_DIV] += v0 * std::log( v0 / v1 ); + } } } else @@ -1046,6 +1053,13 @@ int CV_CompareHistTest::validate_test_results( int /*test_case_idx*/ ) s0 += v0; sq0 += v0*v0; result0[CV_COMP_BHATTACHARYYA] += sqrt(v0*v1); + { + if (v0 <= DBL_EPSILON) + continue; + if (!v1) + v1 = 1e-10; + result0[CV_COMP_KL_DIV] += v0 * std::log( v0 / v1 ); + } } for( node = cvInitSparseMatIterator( sparse1, &iterator ); @@ -1076,7 +1090,8 @@ int CV_CompareHistTest::validate_test_results( int /*test_case_idx*/ ) i == CV_COMP_CHISQR_ALT ? "Alternative Chi-Square" : i == CV_COMP_CORREL ? "Correlation" : i == CV_COMP_INTERSECT ? "Intersection" : - i == CV_COMP_BHATTACHARYYA ? "Bhattacharyya" : "Unknown"; + i == CV_COMP_BHATTACHARYYA ? "Bhattacharyya" : + i == CV_COMP_KL_DIV ? "Kullback-Leibler" : "Unknown"; if( cvIsNaN(v) || cvIsInf(v) ) {