opencv画出轮廓外接矩形

 1     Mat cannyImage;
 2     /// Detect edges using canny
 3     Canny(src, cannyImage, 125, 250, 3);
 4     vector<vector<Point> > contours;
 5     vector<Vec4i> hierarchy;
 6     /// Find contours
 7     findContours(cannyImage, contours, hierarchy, CV_RETR_EXTERNAL /* CV_RETR_EXTERNAL CV_RETR_LIST CV_RETR_CCOMP RETR_TREE CV_RETR_FLOODFILL*/, CHAIN_APPROX_SIMPLE, Point(0, 0));
 8 
 9     /// Approximate contours to polygons + get bounding rects and circles
10     vector<vector<Point> > contours_poly(contours.size());
11     vector<Rect> boundRect(contours.size());
12 
13     for (size_t i = 0; i < contours.size(); i++)
14     {
15         approxPolyDP(Mat(contours[i]), contours_poly[i], 3, true);
16         boundRect[i] = boundingRect(Mat(contours_poly[i]));
17     }