Get the center of contour

通過尋找輪廓的中心，以便對此進行旋轉，校正；

計算方法：

 mu[i].m10/mu[i].m00 , mu[i].m01/mu[i].m00 );

即不同方向的矩進行運算；

static int calCoutorCenter(char* Imgname, vector<Point2f> & mc, double minarea = 0, double whRatio = 1);
int main()
{
	char* filename = new char[50];
	strcpy(filename, "../image/rl_4.jpg");
	//getContoursByCplus(filename);
	vector<Point2f> mc;
	calCoutorCenter(filename, mc);
	delete[] filename;
	return 0;
}

API實現轉自opencv ref.

static int calCoutorCenter(char* Imgname, vector<Point2f> & mc, double minarea, double whRatio)
{
	RNG rng(12345);
	cv::Mat src, dst, canny_output;
	/// Load source image and convert it to gray
	src = imread(Imgname, 0);

	if (!src.data)
	{
		std::cout << "read data error!" << std::endl;
		return -1;
	}
	blur(src, src, Size(3, 3));


	//the pram. for findContours,
	vector<vector<Point> > contours;
	vector<Vec4i> hierarchy;

	/// Detect edges using canny
	Canny(src, canny_output, 80, 255, 3);
	/// Find contours
	findContours(canny_output, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0, 0));
	//CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE

	double maxarea = 0;
	int maxAreaIdx = 0;

	for (int i = 0; i<contours.size(); i++)
	{
		double tmparea = fabs(contourArea(contours[i]));
		if (tmparea>maxarea)
		{
			maxarea = tmparea;
			maxAreaIdx = i;
			continue;
		}

		if (tmparea < minarea)
		{
			//刪除面積小於設定值的輪廓
			contours.erase(contours.begin() + i);
			std::wcout << "delete a small area" << std::endl;
			continue;
		}
		//計算輪廓的直徑寬高
		Rect aRect = boundingRect(contours[i]);
		if ((aRect.width / aRect.height)<whRatio)
		{
			//刪除寬高比例小於設定值的輪廓
			contours.erase(contours.begin() + i);
			std::wcout << "delete a unnomalRatio area" << std::endl;
			continue;
		}
	}
	/// Get the moments
	vector<Moments> mu(contours.size());
	for (int i = 0; i < contours.size(); i++)
	{
		mu[i] = moments(contours[i], false);
	}

	///  Get the mass centers:
	vector<Point2f> mc(contours.size());
	for (int i = 0; i < contours.size(); i++)
	{
		mc[i] = Point2f(mu[i].m10 / mu[i].m00, mu[i].m01 / mu[i].m00);
		std::cout << "mc[" << i << "]=" << mc[i].x << "," << mc[i].y << std::endl;
	}
	/// Draw contours,彩色輪廓
	dst = Mat::zeros(canny_output.size(), CV_8UC3);
	for (int i = 0; i< contours.size(); i++)
	{
		//隨機顏色
		Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
		drawContours(dst, contours, i, color, 2, 8, hierarchy, 0, Point());
		circle(dst, mc[i], 4, color, -1, 8, 0);
	}
	// Create Window
	char* source_window = "countors";
	namedWindow(source_window, CV_WINDOW_NORMAL);
	imshow(source_window, dst);
	imwrite("dst.jpg", dst);
	cv:; waitKey(0);

	return 0;
}