OpenCV直方图用法示例

这个程序根据输入的图像计算出一个色相饱和度直方图，然后利用网格的方式将直方图以网格形式显示。

 #include
 #include
 #include

 #pragma comment(lib, "cv.lib")
 #pragma comment(lib, "cxcore.lib")
 #pragma comment(lib, "highgui.lib")

 int main()
 {
     IplImage* src = NULL;
     src = cvLoadImage ("test.png", 1);

     IplImage* hsv = cvCreateImage (cvGetSize(src), 8, 3);
     cvCvtColor (src, hsv, CV_BGR2HSV);

     IplImage* h_plane = cvCreateImage (cvGetSize(src), 8, 1);
     IplImage* s_plane = cvCreateImage (cvGetSize(src), 8, 1);
     IplImage* v_plane = cvCreateImage (cvGetSize(src), 8, 1);
     IplImage* planes[] = {h_plane, s_plane};
     cvCvtPixToPlane (hsv, h_plane, s_plane, v_plane, 0);

     /*创建和计算直方图*/

     int h_bins = 30;
     int s_bins = 32;
     CvHistogram* hist = NULL;
     int hist_size[] = {h_bins, s_bins};
     float h_ranges[] = {0, 180};
     float s_ranges[] = {0, 255};
     float* ranges[] = {h_ranges, s_ranges};
     hist = cvCreateHist (2, hist_size, CV_HIST_ARRAY, ranges, 1);
     cvCalcHist (planes, hist, 0, 0); //计算直方图
     cvNormalizeHist (hist, 1.0);   //归一化

     /*测试匹配度并输出*/

     /*double like = cvCompareHist (hist, hist, CV_COMP_INTERSECT);
     printf("%lf\n", like);*/

     /*创建一个图像来可视化我们的直方图*/

     int scale = 10;
     IplImage* hist_img = cvCreateImage (cvSize(h_bins * scale, s_bins * scale), 8, 3);
     cvZero (hist_img);

     /*用小的灰度方格填充hist_img*/

     float max_value = 0;
     cvGetMinMaxHistValue (hist, 0, &max_value, 0, 0);
     for (int h = 0; h < h_bins; h++)
     {
         for (int s = 0; s < s_bins; s++)
         {
             float bin_val = cvQueryHistValue_2D (hist, h, s);
             int intensity = cvRound (bin_val * 255 / max_value);
             cvRectangle (hist_img, cvPoint(h*scale, s*scale), cvPoint((h+1)*scale-1, (s+1)*scale-1),
                 CV_RGB(intensity, intensity, intensity),CV_FILLED);
         }
     }
     cvNamedWindow ("src", 1);
     cvShowImage ("src", src);
     cvNamedWindow ("H-S histogram", 1);
     cvShowImage ("H-S histogram", hist_img);

     cvWaitKey (0);

     cvReleaseImage (&src);
     cvReleaseImage (&hsv);
     cvReleaseImage (&hist_img);
     cvReleaseHist (&hist);

     return 0;
 }