void inRange(InputArray src, InputArray lowerb, InputArray upperb, OutputArray dst);

#include<opencv2/opencv.hpp>
using namespace cv;

int main()
{
	VideoCapture capture;
	capture.open(0);
	if(!capture.isOpened())
	{
		printf("can not open video file  \n");
		return -1;
	}
	Mat frame, dst;
	Mat kernel;
	//開操作處理
	kernel = getStructuringElement(MORPH_RECT, Size(5, 5));

	namedWindow("input", CV_WINDOW_AUTOSIZE);
	namedWindow("output", CV_WINDOW_AUTOSIZE);
	std::vector<std::vector<Point>> contours;
	std::vector<Vec4i> hireachy;
	Rect rect;
	Point2f center;
	float radius=20;

	while (capture.read(frame))
	{	
		//blur(frame, dst, Size(5,5));
		inRange(frame, Scalar(0,80,80), Scalar(50,255,255), dst);
		//開操作
		morphologyEx(dst,dst,MORPH_OPEN,kernel);
		//獲取邊界
		findContours(dst, contours, hireachy, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE, Point(0,0));
		//框選面積最大的邊界
		if (contours.size() > 0)
		{
			double maxArea=0;
			for (int i = 0; i < contours.size(); i++)
			{
				double area = contourArea(contours[static_cast<int>(i)]);
				if (area > maxArea)
				{
					maxArea = area;
					rect = boundingRect(contours[static_cast<int>(i)]);
					minEnclosingCircle(contours[static_cast<int>(i)], center, radius);
				}
			}
		}
		//矩形框
		//rectangle(frame,rect, Scalar(0,255,0),2);
		//圓形框
		circle(frame, Point(center.x,center.y), (int)radius, Scalar(0,255,0), 2);
		imshow("input", frame);
		imshow("output", dst);

		waitKey(100);
	}

	capture.release();
	return 0;
}