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/**
* @function calcHist_Demo.cpp
* @brief Demo code to use the function calcHist
* @author
*/
#include "opencv2/highgui.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
using namespace std;
using namespace cv;
/**
* @function main
*/
int main(int argc, char** argv)
{
//! [Load image]
CommandLineParser parser( argc, argv, "{@input | lena.jpg | input image}" );
Mat src = imread( samples::findFile( parser.get<String>( "@input" ) ), IMREAD_COLOR );
if( src.empty() )
{
return EXIT_FAILURE;
}
//! [Load image]
//! [Separate the image in 3 places ( B, G and R )]
vector<Mat> bgr_planes;
split( src, bgr_planes );
//! [Separate the image in 3 places ( B, G and R )]
//! [Establish the number of bins]
int histSize = 256;
//! [Establish the number of bins]
//! [Set the ranges ( for B,G,R) )]
float range[] = { 0, 256 }; //the upper boundary is exclusive
const float* histRange[] = { range };
//! [Set the ranges ( for B,G,R) )]
//! [Set histogram param]
bool uniform = true, accumulate = false;
//! [Set histogram param]
//! [Compute the histograms]
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 );
//! [Compute the histograms]
//! [Draw the histograms for B, G and R]
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) );
//! [Draw the histograms for B, G and R]
//! [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() );
//! [Normalize the result to ( 0, histImage.rows )]
//! [Draw for each channel]
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 );
}
//! [Draw for each channel]
//! [Display]
imshow("Source image", src );
imshow("calcHist Demo", histImage );
waitKey();
//! [Display]
return EXIT_SUCCESS;
}
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