OpenCV实现图像轮廓检测以及外接矩形

// extract_contours.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include<cv.h> #include<highgui.h> using namespace cv;using namespace std;int _tmain(int argc, _TCHAR* argv[]){ //load src image string img_name="..//image_norm//71253.jpg"; Mat image=imread(img_name);  imshow("src_image",image); cvWaitKey(0); //convert into gray image Mat gray(image.size(),CV_8U);  cvtColor(image,gray,CV_BGR2GRAY); imshow("gray",gray); cvWaitKey(0); //convert into bin image threshold(gray,gray,128,255,THRESH_BINARY);//转换成2值图像  imshow("binary",gray);  cvWaitKey(0); // Detecting contours  vector<vector<Point>> contours; //定义轮廓集合  vector<Vec4i> hierarchy;  findContours(gray, contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_NONE);//CV_RETR_EXTERNAL只检测外部轮廓 // draw black contours on white image  Mat result(gray.size(),CV_8U,Scalar(255));  int index = 0;  for (; index >= 0; index = hierarchy[index][0]) //hierarchy[index][0]表示后一个轮廓 {  Scalar color(rand() & 255, rand() & 255, rand() & 255);  drawContours(result, contours, index, Scalar(0), 1, 8, hierarchy);//描绘字符的外轮廓  Rect rect = boundingRect(contours[index]);//检测外轮廓  rectangle(result, rect, Scalar(0,0,255), 3);//对外轮廓加矩形框  }  imshow("Contours on white image",result);  cvWaitKey(0); //draw contours on the original image  Mat original=imread(img_name);  int index_ori = 0;  for (; index_ori >= 0; index_ori = hierarchy[index_ori][0])  { Scalar color(rand() & 255, rand() & 255, rand() & 255);  //描绘字符的外轮廓 drawContours(original,contours,index_ori,Scalar(255),1,8, hierarchy);  Rect rect = boundingRect(contours[index_ori]);//检测外轮廓 //对外轮廓加加矩形框  rectangle(original, rect, Scalar(0,0,255), 3);  } //print contours info cout<<"The number of external contours:"<<contours.size()<<endl; imshow("Contours on original image",original);  waitKey(0); return 0;}