--- /dev/null
+/**
+ * @function calcHist_Demo.cpp
+ * @brief Demo code to use the function calcHist
+ * @author
+ */
+
+#include "opencv2/highgui/highgui.hpp"
+#include "opencv2/imgproc/imgproc.hpp"
+#include <iostream>
+#include <stdio.h>
+
+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<Mat> 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<float>(i-1)) ) ,
+ Point( bin_w*(i), hist_h - cvRound(r_hist.at<float>(i)) ),
+ Scalar( 0, 0, 255), 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(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 );
+ }
+
+ /// Display
+ namedWindow("calcHist Demo", CV_WINDOW_AUTOSIZE );
+ imshow("calcHist Demo", histImage );
+
+ waitKey(0);
+
+ return 0;
+
+}