int* computeHistogramGrayscale(Mat img)
{
    int *hist= new int[256]();
    int rows = img.rows, cols = img.cols;
    for (int r = 0; r < rows; r++)
    {
        for (int c = 0; c < cols; c++)
        {
            hist[img.at<uchar>(r, c)]++;
        }
    }
    return hist;
}
int* computeHistogramGrayscaleCumulative(int *hist)
{
    int *histC = new int[256]();
    int current = 0;
    for (int i = 0; i < 256; i++)
    {
        current += hist[i];
        histC[i]= current;
    }
    return histC;
}
//////////////////////////////////////////////////////////////////////////////////////////
float* computeDeviation(int *histC,Mat src)
{
    float *histf = new float[256]();
    int current = 0;
    float pixels = src.rows*src.cols;
    for (int i = 0; i < 256; i++)
    {
        histf[i] = ((float)255 * histC[i])/ pixels;
    }
    return histf;
}
Mat proc_img_eq(Mat &img)
{
    Mat dst = img.clone();
    int *hist = computeHistogramGrayscale(img);
    int *histC = computeHistogramGrayscaleCumulative(hist);
    float *t = computeDeviation(histC, img);
    int rows = img.rows, cols = img.cols;
    for (int r = 0; r < rows; r++)
        for (int c = 0; c < cols; c++)
            dst.at<uchar>(r, c) = t[img.at<uchar>(r, c)];
    return dst;
}
void lab7_histogram_all() {
    char fname[MAX_PATH];
    while (openFileDlg(fname))
    {
        double t = (double)getTickCount(); // Get the current time [s]
        Mat src = imread(fname, CV_LOAD_IMAGE_GRAYSCALE);
        int *hist = computeHistogramGrayscale(src);
        int *histC = computeHistogramGrayscaleCumulative(hist);
        showHistogram("Histogram", hist, 256, 500);
        showHistogram("HistogramCummulative", histC, 256, 500);
        Mat dst = proc_img_eq(src);
        int *histd = computeHistogramGrayscale(dst);
        int *histCd = computeHistogramGrayscaleCumulative(histd);
        showHistogram("Histogram dst", histd, 256, 500);
        showHistogram("HistogramCummulative dst", histCd, 256, 500);
        imshow("src", src);
        imshow("dst", dst);
        // Get the current time again and compute the time difference [s]
        t = ((double)getTickCount() - t) / getTickFrequency();



        // Print (in the console window) the processing time in [ms]
        printf("Time = %.3f [ms]\n", t * 1000);
        waitKey();
    }
}