#include "opencv2/objdetect/objdetect.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>

using namespace std;
using namespace cv;

int main(int, char**)
{
    Mat gray = imread("../data/12.PNG", 0);
    namedWindow("Gray", 1);    imshow("Gray", gray);

    // Initialize parameters
    int histSize = 256;    // bin size
    float range[] = { 0, 255 };
    const float *ranges[] = { range };

    // Calculate histogram
    MatND hist;
    calcHist(&gray, 1, 0, Mat(), hist, 1, &histSize, ranges, true, false);

    // Show the calculated histogram in command window
    double total;
    total = gray.rows * gray.cols;
    for (int h = 0; h < histSize; h++)
    {
        float binVal = hist.at<float>(h);
        cout << " " << binVal;
    }

    // Plot the histogram
    int hist_w = 512; int hist_h = 400;
    int bin_w = cvRound((double)hist_w / histSize);

    Mat histImage(hist_h, hist_w, CV_8UC1, Scalar(0, 0, 0));
    normalize(hist, hist, 0, histImage.rows, NORM_MINMAX, -1, Mat());

    for (int i = 1; i < histSize; i++)
    {
        line(histImage, Point(bin_w*(i - 1), hist_h - cvRound(hist.at<float>(i - 1))),
            Point(bin_w*(i), hist_h - cvRound(hist.at<float>(i))),
            Scalar(255, 0, 0), 2, 8, 0);
    }

    namedWindow("Result", 1);    imshow("Result", histImage);

    waitKey(0);
    return 0;
}