distribute-histogram.cpp

#include <opencv/cv.h>
#include <opencv/highgui.h>
#include <stdio.h>
#include <stdlib.h>

void etirerHistogramme(IplImage ** img){
  IplImage * image = *img;
  if (image->nChannels != 1) return;

  int p_min = 255;
  int p_max = 0;
  CvScalar pixel;

  for (int x = 0; x < image->width; x++) {
    for (int y = 0; y < image->height; y++) {
      pixel = cvGet2D(image, y, x);
      if (pixel.val[0] < p_min) p_min = pixel.val[0];
      if (pixel.val[0] > p_max) p_max = pixel.val[0];
    }
  }

  printf("Min = %d, Max = %d\n", p_min, p_max);

  for (int x = 0; x < image->width; x++) {
    for (int y = 0; y < image->height; y++) {
      pixel = cvGet2D(image, y, x);
      pixel.val[0] = 255 * (pixel.val[0] - p_min) / (p_max - p_min);
      cvSet2D(image, y, x, pixel);
    }
  }
}

int main(int argc, char const *argv[]) {
  if (argc == 2 || argc == 3) {
    IplImage * original = cvLoadImage(argv[1]);
    double ratio = 1;
    if (argc == 3) {
      ratio = atof(argv[2]);
    }
    IplImage * colored = cvCreateImage(
        cvSize(original->width * ratio, original->height * ratio),
        original->depth,
        original->nChannels
    );
    cvResize(original, colored);
    IplImage * grayscale = cvCreateImage(cvGetSize(colored), colored->depth, 1);
    int flip = 0;
    if (colored->origin != IPL_ORIGIN_TL) flip = CV_CVTIMG_FLIP;
    cvConvertImage(colored, grayscale, flip);
    IplImage * normalized = cvCloneImage(grayscale);
    etirerHistogramme(&normalized);
    cvNamedWindow("Colored", CV_WINDOW_AUTOSIZE);
    cvNamedWindow("Grayscale", CV_WINDOW_AUTOSIZE);
    cvNamedWindow("Normalized", CV_WINDOW_AUTOSIZE);
    cvShowImage("Colored", colored);
    cvShowImage("Grayscale", grayscale);
    cvShowImage("Normalized", normalized);
    cvWaitKey(0);
    cvDestroyAllWindows();
    cvReleaseImage(&colored);
    cvReleaseImage(&grayscale);
    cvReleaseImage(&normalized);
  } else {
    printf("Usage : %s <image> [ratio]\n", argv[0]);
  }
  return 0;
}