diff --git a/samples/cpp/tutorial_code/Histograms_Matching/calcHist_Demo.cpp b/samples/cpp/tutorial_code/Histograms_Matching/calcHist_Demo.cpp new file mode 100644 index 0000000000000000000000000000000000000000..ae2496320c529f45932a8b228a76dab790205212 --- /dev/null +++ b/samples/cpp/tutorial_code/Histograms_Matching/calcHist_Demo.cpp @@ -0,0 +1,81 @@ +/** + * @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 ( R, G and B ) + vector rgb_planes; + split( src, rgb_planes ); + + /// Establish the number of bins + int histSize = 255; + + /// Set the ranges ( for R,G,B) ) + float range[] = { 0, 255 } ; + const float* histRange = { range }; + + bool uniform = true; bool accumulate = false; + + Mat r_hist, g_hist, b_hist; + + /// Compute the histograms: + calcHist( &rgb_planes[0], 1, 0, Mat(), r_hist, 1, &histSize, &histRange, uniform, accumulate ); + calcHist( &rgb_planes[1], 1, 0, Mat(), g_hist, 1, &histSize, &histRange, uniform, accumulate ); + calcHist( &rgb_planes[2], 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate ); + + // Draw the histograms for R, G and B + int hist_w = 400; int hist_h = 400; + int bin_w = cvRound( (double) hist_w/histSize ); + + Mat histImage( hist_w, hist_h, CV_8UC3, Scalar( 0,0,0) ); + + /// Normalize the result to [ 0, histImage.rows ] + normalize(r_hist, r_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() ); + normalize(g_hist, g_hist, 0, histImage.rows, NORM_MINMAX, -1, Mat() ); + normalize(b_hist, b_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(r_hist.at(i-1)) ) , + Point( bin_w*(i), hist_h - cvRound(r_hist.at(i)) ), + Scalar( 0, 0, 255), 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(b_hist.at(i-1)) ) , + Point( bin_w*(i), hist_h - cvRound(b_hist.at(i)) ), + Scalar( 255, 0, 0), 2, 8, 0 ); + } + + /// Display + namedWindow("calcHist Demo", CV_WINDOW_AUTOSIZE ); + imshow("calcHist Demo", histImage ); + + waitKey(0); + + return 0; + +}