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Author: yashk2000

histogram.cpp

@@ -0,0 +1,49 @@
+#include "opencv2/highgui.hpp"
+#include "opencv2/imgcodecs.hpp"
+#include "opencv2/imgproc.hpp"
+#include <iostream>
+
+using namespace std;
+using namespace cv;
+int main(int argc, char** argv)
+{
+    Mat src = imread(argv[1]);
+    if( src.empty() )
+    {
+        printf("No image found");
+        return -1;
+    }
+   
+    vector<Mat> bgr_planes;
+    split( src, bgr_planes );
+    int histSize = 256;
+    float range[] = { 0, 256 }; //the upper boundary is exclusive
+    const float* histRange = { range };
+    bool uniform = true, accumulate = false;
+    Mat b_hist, g_hist, r_hist;
+    calcHist( &bgr_planes[0], 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate );
+    calcHist( &bgr_planes[1], 1, 0, Mat(), g_hist, 1, &histSize, &histRange, uniform, accumulate );
+    calcHist( &bgr_planes[2], 1, 0, Mat(), r_hist, 1, &histSize, &histRange, uniform, accumulate );
+    int hist_w = 512, hist_h = 400;
+    int bin_w = cvRound( (double) hist_w/histSize );
+    Mat histImage( hist_h, hist_w, CV_8UC3, Scalar( 0,0,0) );
+    normalize(b_hist, b_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
+    normalize(g_hist, g_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
+    normalize(r_hist, r_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() );
+    for( int i = 1; i < histSize; i++ )
+    {
+        line( histImage, Point( bin_w*(i-1), hist_h - cvRound(b_hist.at<float>(i-1)) ),
+              Point( bin_w*(i), hist_h - cvRound(b_hist.at<float>(i)) ),
+              Scalar( 255, 0, 0), 2, 8, 0  );
+        line( histImage, Point( bin_w*(i-1), hist_h - cvRound(g_hist.at<float>(i-1)) ),
+              Point( bin_w*(i), hist_h - cvRound(g_hist.at<float>(i)) ),
+              Scalar( 0, 255, 0), 2, 8, 0  );
+        line( histImage, Point( bin_w*(i-1), hist_h - cvRound(r_hist.at<float>(i-1)) ),
+              Point( bin_w*(i), hist_h - cvRound(r_hist.at<float>(i)) ),
+              Scalar( 0, 0, 255), 2, 8, 0  );
+    }
+    imshow("Source image", src );
+    imshow("calcHist Demo", histImage );
+    waitKey();
+    return 0;
+}