1 /** 2 * @function calcHist_Demo.cpp 3 * @brief Demo code to use the function calcHist 4 * @author 5 */ 6 7 #include "opencv2/highgui/highgui.hpp" 8 #include "opencv2/imgcodecs.hpp" 9 #include "opencv2/imgproc/imgproc.hpp" 10 #include <iostream> 11 #include <stdio.h> 12 13 using namespace std; 14 using namespace cv; 15 16 /** 17 * @function main 18 */ 19 int main( int, char** argv ) 20 { 21 Mat src, dst; 22 23 /// Load image 24 src = imread( argv[1], 1 ); 25 26 if( src.empty() ) 27 { return -1; } 28 29 /// Separate the image in 3 places ( B, G and R ) 30 vector<Mat> bgr_planes; 31 split( src, bgr_planes ); 32 33 /// Establish the number of bins 34 int histSize = 256; 35 36 /// Set the ranges ( for B,G,R) ) 37 float range[] = { 0, 256 } ; 38 const float* histRange = { range }; 39 40 bool uniform = true; bool accumulate = false; 41 42 Mat b_hist, g_hist, r_hist; 43 44 /// Compute the histograms: 45 calcHist( &bgr_planes[0], 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate ); 46 calcHist( &bgr_planes[1], 1, 0, Mat(), g_hist, 1, &histSize, &histRange, uniform, accumulate ); 47 calcHist( &bgr_planes[2], 1, 0, Mat(), r_hist, 1, &histSize, &histRange, uniform, accumulate ); 48 49 // Draw the histograms for B, G and R 50 int hist_w = 512; int hist_h = 400; 51 int bin_w = cvRound( (double) hist_w/histSize ); 52 53 Mat histImage( hist_h, hist_w, CV_8UC3, Scalar( 0,0,0) ); 54 55 /// Normalize the result to [ 0, histImage.rows ] 56 normalize(b_hist, b_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() ); 57 normalize(g_hist, g_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() ); 58 normalize(r_hist, r_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() ); 59 60 /// Draw for each channel 61 for( int i = 1; i < histSize; i++ ) 62 { 63 line( histImage, Point( bin_w*(i-1), hist_h - cvRound(b_hist.at<float>(i-1)) ) , 64 Point( bin_w*(i), hist_h - cvRound(b_hist.at<float>(i)) ), 65 Scalar( 255, 0, 0), 2, 8, 0 ); 66 line( histImage, Point( bin_w*(i-1), hist_h - cvRound(g_hist.at<float>(i-1)) ) , 67 Point( bin_w*(i), hist_h - cvRound(g_hist.at<float>(i)) ), 68 Scalar( 0, 255, 0), 2, 8, 0 ); 69 line( histImage, Point( bin_w*(i-1), hist_h - cvRound(r_hist.at<float>(i-1)) ) , 70 Point( bin_w*(i), hist_h - cvRound(r_hist.at<float>(i)) ), 71 Scalar( 0, 0, 255), 2, 8, 0 ); 72 } 73 74 /// Display 75 namedWindow("calcHist Demo", WINDOW_AUTOSIZE ); 76 imshow("calcHist Demo", histImage ); 77 78 waitKey(0); 79 80 return 0; 81 82 } 83
