/** * @function calcHist_Demo.cpp * @brief Demo code to use the function calcHist * @author */ #include "opencv2/highgui/highgui.hpp" #include "opencv2/imgproc/imgproc.hpp" #include #include using namespace std; using namespace cv; /** * @function main */ int main( int argc, char** argv ) { Mat src, dst; /// Load image src = imread( argv[1], 1 ); if( !src.data ) { return -1; } /// Separate the image in 3 places ( B, G and R ) vector bgr_planes; split( src, bgr_planes ); /// Establish the number of bins int histSize = 256; /// Set the ranges ( for B,G,R) ) float range[] = { 0, 256 } ; const float* histRange = { range }; bool uniform = true; bool accumulate = false; Mat b_hist, g_hist, r_hist; /// Compute the histograms: 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 ); // Draw the histograms for B, G and R int hist_w = 512; int hist_h = 400; int bin_w = cvRound( (double) hist_w/histSize ); Mat histImage( hist_h, hist_w, CV_8UC3, Scalar( 0,0,0) ); /// Normalize the result to [ 0, histImage.rows ] 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() ); /// Draw for each channel for( int i = 1; i < histSize; i++ ) { line( histImage, Point( bin_w*(i-1), hist_h - cvRound(b_hist.at(i-1)) ) , Point( bin_w*(i), hist_h - cvRound(b_hist.at(i)) ), Scalar( 255, 0, 0), 2, 8, 0 ); line( histImage, Point( bin_w*(i-1), hist_h - cvRound(g_hist.at(i-1)) ) , Point( bin_w*(i), hist_h - cvRound(g_hist.at(i)) ), Scalar( 0, 255, 0), 2, 8, 0 ); line( histImage, Point( bin_w*(i-1), hist_h - cvRound(r_hist.at(i-1)) ) , Point( bin_w*(i), hist_h - cvRound(r_hist.at(i)) ), Scalar( 0, 0, 255), 2, 8, 0 ); } /// Display namedWindow("calcHist Demo", CV_WINDOW_AUTOSIZE ); imshow("calcHist Demo", histImage ); waitKey(0); return 0; }