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POresults compareHist in openCV
 

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  1. POresults compareHist in openCV
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    <p>I'm trying to compare two histograms which I stored as an array. I'm new with the c++ interface (cv::Mat) and calculating histograms in OpenCV. </p> <p>My code:</p> <pre><code>int testArr1[4] = {12, 10, 11, 11}; int testArr2[4] = {12, 0, 11, 0}; cv::Mat M1 = cv::Mat(1,4,CV_8UC1, testArr1); cv::Mat M2 = cv::Mat(1,4,CV_8UC1, testArr2); int histSize = 4; float range[] = {0, 20}; const float* histRange = {range}; bool uniform = true; bool accumulate = false; cv::Mat a1_hist, a2_hist; cv::calcHist(&amp;M1, 1, 0, cv::Mat(), a1_hist, 1, &amp;histSize, &amp;histRange, uniform, accumulate ); cv::calcHist(&amp;M2, 1, 0, cv::Mat(), a2_hist, 1, &amp;histSize, &amp;histRange, uniform, accumulate ); double compar_c = cv::compareHist(a1_hist, a2_hist, CV_COMP_CORREL); double compar_chi = cv::compareHist(a1_hist, a2_hist, CV_COMP_CHISQR); double compar_bh = cv::compareHist(a1_hist, a2_hist, CV_COMP_BHATTACHARYYA); double compar_i = cv::compareHist(a1_hist, a2_hist, CV_COMP_INTERSECT); cout &lt;&lt; "compare(CV_COMP_CORREL): " &lt;&lt; compar_c &lt;&lt; "\n"; cout &lt;&lt; "compare(CV_COMP_CHISQR): " &lt;&lt; compar_chi &lt;&lt; "\n"; cout &lt;&lt; "compare(CV_COMP_BHATTACHARYYA): " &lt;&lt; compar_bh &lt;&lt; "\n"; cout &lt;&lt; "compare(CV_COMP_INTERSECT): " &lt;&lt; compar_i &lt;&lt; "\n"; </code></pre> <p>The results are a bit unexpected:</p> <pre><code>compare(CV_COMP_CORREL): 1 compare(CV_COMP_CHISQR): 0 compare(CV_COMP_BHATTACHARYYA): 0 compare(CV_COMP_INTERSECT): 4 </code></pre> <p>For intersection, for example, I expected something like 0.5. What am I doing wrong? Can I not put arrays in a cv::mat? Or did I choose the wrong histogram "settings"?</p>
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