(轉）OpenCV—連通域分析connectedComponentsWithStats()

原文地址

文章2

原文補充：

#include<opencv2/opencv.hpp>
#include<algorithm>
#include<iostream>

using namespace std;
using namespace cv;

int main()
{
      cv::Mat src_img, img_bool, labels, stats, centroids, img_color, img_gray;

      if( (src_img = cv::imread("13.png",0)).empty())
      {
            cout<<"load image error"<<endl;
            return -1;
      }
      cv::threshold(src_img, img_bool, 0, 255, cv::THRESH_OTSU);
      //連通域計算
      int nccomps = cv::connectedComponentsWithStats (
            img_bool, //二值圖像
            labels,     //和原圖一樣大的標記圖
            stats, //nccomps×5的矩陣 表示每個連通區域的外接矩形和面積（就是pixel的個數）
            centroids //nccomps×2的矩陣 表示每個連通區域的質心
            );


      char title[1024];
      sprintf(title,"原圖中連通區域數：%d\n",nccomps);
      cv::String num_connect(title);
      cv::imshow(num_connect, img_bool);

      //去除過小區域，初始化顏色表
      vector<cv::Vec3b> colors(nccomps);
      colors[0] = cv::Vec3b(0,0,0); // background pixels remain black.
      for(int i = 1; i < nccomps; i++ ) {
            colors[i] = cv::Vec3b(rand()%256, rand()%256, rand()%256);
            //輸出每個連通域的像素個數
            cout<<stats.at<int>(i, cv::CC_STAT_AREA)<<endl;
             //去除面積小於20的連通域
            if( stats.at<int>(i, cv::CC_STAT_AREA) < 20 )
                  colors[i] = cv::Vec3b(0,0,0); // small regions are painted with black too.
      }
      //按照label值，對不同的連通域進行着色
      img_color = cv::Mat::zeros(src_img.size(), CV_8UC3);
      for( int y = 0; y < img_color.rows; y++ )
            for( int x = 0; x < img_color.cols; x++ )
            {
                  int label = labels.at<int>(y, x);
                  CV_Assert(0 <= label && label <= nccomps);
                  img_color.at<cv::Vec3b>(y, x) = colors[label];
            }

      //統計降噪后的連通區域
      cv::cvtColor(img_color,img_gray,cv::COLOR_BGR2GRAY);
      cv::threshold(img_gray, img_gray, 1, 255, cv::THRESH_BINARY);
      nccomps = cv::connectedComponentsWithStats (img_gray, labels,stats,centroids);
      sprintf(title,"num of connect area after filter：%d\n",nccomps);
      num_connect = title;
      namedWindow(num_connect,0);
      cv::imshow(num_connect, img_color);
      cv::waitKey();
      return 0;
}