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Merge pull request #1248 from vkocheganov:chi_square_alt

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Roman Donchenko 2013-08-28 11:44:40 +04:00 committed by OpenCV Buildbot
commit 1840fd5f00
4 changed files with 38 additions and 11 deletions
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11
modules/imgproc/doc/histograms.rst
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@ -173,6 +173,8 @@ Compares two histograms.
* **CV_COMP_CHISQR** Chi-Square
* **CV_COMP_CHISQR_ALT** Alternative Chi-Square
* **CV_COMP_INTERSECT** Intersection
* **CV_COMP_BHATTACHARYYA** Bhattacharyya distance
@ -202,6 +204,14 @@ The functions ``compareHist`` compare two dense or two sparse histograms using t
d(H_1,H_2) = \sum _I \frac{\left(H_1(I)-H_2(I)\right)^2}{H_1(I)}
* Alternative Chi-Square (``method=CV_COMP_CHISQR_ALT``)
.. math::
d(H_1,H_2) = 2 * \sum _I \frac{\left(H_1(I)-H_2(I)\right)^2}{H_1(I)+H_2(I)}
This alternative formula is regularly used for texture comparison. See e.g. [Puzicha1997]_.
* Intersection (``method=CV_COMP_INTERSECT``)
.. math::
@ -493,3 +503,4 @@ The function clears histogram bins that are below the specified threshold.
.. [RubnerSept98] Y. Rubner. C. Tomasi, L.J. Guibas. *The Earth Mover’s Distance as a Metric for Image Retrieval*. Technical Report STAN-CS-TN-98-86, Department of Computer Science, Stanford University, September 1998.
.. [Puzicha1997] Puzicha, J., Hofmann, T., and Buhmann, J. *Non-parametric similarity measures for unsupervised texture segmentation and image retrieval.* In Proc. IEEE Conf. Computer Vision and Pattern Recognition, San Juan, Puerto Rico, pp. 267-272, 1997.

3
modules/imgproc/include/opencv2/imgproc/types_c.h
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@ -508,7 +508,8 @@ enum
CV_COMP_CHISQR =1,
CV_COMP_INTERSECT =2,
CV_COMP_BHATTACHARYYA =3,
CV_COMP_HELLINGER =CV_COMP_BHATTACHARYYA
CV_COMP_HELLINGER =CV_COMP_BHATTACHARYYA,
CV_COMP_CHISQR_ALT =4
};
/* Mask size for distance transform */

26
modules/imgproc/src/histogram.cpp
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@ -1990,12 +1990,12 @@ double cv::compareHist( InputArray _H1, InputArray _H2, int method )
const float* h2 = (const float*)it.planes[1].data;
len = it.planes[0].rows*it.planes[0].cols*H1.channels();
if( method == CV_COMP_CHISQR )
if( (method == CV_COMP_CHISQR) || (method == CV_COMP_CHISQR_ALT))
{
for( j = 0; j < len; j++ )
{
double a = h1[j] - h2[j];
double b = h1[j];
double b = (method == CV_COMP_CHISQR) ? h1[j] : h1[j] + h2[j];
if( fabs(b) > DBL_EPSILON )
result += a*a/b;
}
@ -2034,7 +2034,9 @@ double cv::compareHist( InputArray _H1, InputArray _H2, int method )
CV_Error( CV_StsBadArg, "Unknown comparison method" );
}
if( method == CV_COMP_CORREL )
if( method == CV_COMP_CHISQR_ALT )
result *= 2;
else if( method == CV_COMP_CORREL )
{
size_t total = H1.total();
double scale = 1./total;
@ -2063,13 +2065,13 @@ 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 )
if( PH1->nzcount() > PH2->nzcount() && method != CV_COMP_CHISQR && method != CV_COMP_CHISQR_ALT)
std::swap(PH1, PH2);
SparseMatConstIterator it = PH1->begin();
int N1 = (int)PH1->nzcount(), N2 = (int)PH2->nzcount();
if( method == CV_COMP_CHISQR )
if( (method == CV_COMP_CHISQR) || (method == CV_COMP_CHISQR_ALT) )
{
for( i = 0; i < N1; i++, ++it )
{
@ -2077,7 +2079,7 @@ double cv::compareHist( const SparseMat& H1, const SparseMat& H2, int method )
const SparseMat::Node* node = it.node();
float v2 = PH2->value<float>(node->idx, (size_t*)&node->hashval);
double a = v1 - v2;
double b = v1;
double b = (method == CV_COMP_CHISQR) ? v1 : v1 + v2;
if( fabs(b) > DBL_EPSILON )
result += a*a/b;
}
@ -2146,6 +2148,9 @@ double cv::compareHist( const SparseMat& H1, const SparseMat& H2, int method )
else
CV_Error( CV_StsBadArg, "Unknown comparison method" );
if( method == CV_COMP_CHISQR_ALT )
result *= 2;
return result;
}
@ -2485,13 +2490,13 @@ cvCompareHist( const CvHistogram* hist1,
CvSparseMatIterator iterator;
CvSparseNode *node1, *node2;
if( mat1->heap->active_count > mat2->heap->active_count && method != CV_COMP_CHISQR )
if( mat1->heap->active_count > mat2->heap->active_count && method != CV_COMP_CHISQR && method != CV_COMP_CHISQR_ALT)
{
CvSparseMat* t;
CV_SWAP( mat1, mat2, t );
}
if( method == CV_COMP_CHISQR )
if( (method == CV_COMP_CHISQR) || (method == CV_COMP_CHISQR_ALT) )
{
for( node1 = cvInitSparseMatIterator( mat1, &iterator );
node1 != 0; node1 = cvGetNextSparseNode( &iterator ))
@ -2500,7 +2505,7 @@ cvCompareHist( const CvHistogram* hist1,
uchar* node2_data = cvPtrND( mat2, CV_NODE_IDX(mat1,node1), 0, 0, &node1->hashval );
double v2 = node2_data ? *(float*)node2_data : 0.f;
double a = v1 - v2;
double b = v1;
double b = (method == CV_COMP_CHISQR) ? v1 : v1 + v2;
if( fabs(b) > DBL_EPSILON )
result += a*a/b;
}
@ -2590,6 +2595,9 @@ cvCompareHist( const CvHistogram* hist1,
else
CV_Error( CV_StsBadArg, "Unknown comparison method" );
if( method == CV_COMP_CHISQR_ALT )
result *= 2;
return result;
}

9
modules/imgproc/test/test_histograms.cpp
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@ -948,7 +948,7 @@ int CV_ThreshHistTest::validate_test_results( int /*test_case_idx*/ )
class CV_CompareHistTest : public CV_BaseHistTest
{
public:
enum { MAX_METHOD = 4 };
enum { MAX_METHOD = 5 };
CV_CompareHistTest();
protected:
@ -1014,6 +1014,8 @@ int CV_CompareHistTest::validate_test_results( int /*test_case_idx*/ )
result0[CV_COMP_INTERSECT] += MIN(v0,v1);
if( fabs(v0) > DBL_EPSILON )
result0[CV_COMP_CHISQR] += (v0 - v1)*(v0 - v1)/v0;
if( fabs(v0 + v1) > DBL_EPSILON )
result0[CV_COMP_CHISQR_ALT] += (v0 - v1)*(v0 - v1)/(v0 + v1);
s0 += v0;
s1 += v1;
sq0 += v0*v0;
@ -1039,6 +1041,8 @@ int CV_CompareHistTest::validate_test_results( int /*test_case_idx*/ )
result0[CV_COMP_INTERSECT] += MIN(v0,v1);
if( fabs(v0) > DBL_EPSILON )
result0[CV_COMP_CHISQR] += (v0 - v1)*(v0 - v1)/v0;
if( fabs(v0 + v1) > DBL_EPSILON )
result0[CV_COMP_CHISQR_ALT] += (v0 - v1)*(v0 - v1)/(v0 + v1);
s0 += v0;
sq0 += v0*v0;
result0[CV_COMP_BHATTACHARYYA] += sqrt(v0*v1);
@ -1053,6 +1057,8 @@ int CV_CompareHistTest::validate_test_results( int /*test_case_idx*/ )
}
}
result0[CV_COMP_CHISQR_ALT] *= 2;
t = (sq0 - s0*s0/total_size)*(sq1 - s1*s1/total_size);
result0[CV_COMP_CORREL] = fabs(t) > DBL_EPSILON ?
(result0[CV_COMP_CORREL] - s0*s1/total_size)/sqrt(t) : 1;
@ -1067,6 +1073,7 @@ int CV_CompareHistTest::validate_test_results( int /*test_case_idx*/ )
double v = result[i], v0 = result0[i];
const char* method_name =
i == CV_COMP_CHISQR ? "Chi-Square" :
i == CV_COMP_CHISQR_ALT ? "Alternative Chi-Square" :
i == CV_COMP_CORREL ? "Correlation" :
i == CV_COMP_INTERSECT ? "Intersection" :
i == CV_COMP_BHATTACHARYYA ? "Bhattacharyya" : "Unknown";