OpenCvSharp裁剪图像、寻找圆心

裁剪图像

            OpenCvSharp.Rect rect = new OpenCvSharp.Rect(4800, 2100, 400, 900);//设置范围
            OpenCvSharp.Mat cropped_image = new OpenCvSharp.Mat(Img, rect);//裁剪图像

static private void FindCenterOfCircle(Mat mat) {

            mat.ConvertTo(mat, MatType.CV_8UC1,1.0/255,0);//转换成CV_8UC1
            Cv2.ImWrite("显示原图.tiff", mat);
            
            var mean = Cv2.Mean(mat);
            //阈值处理
            double thresh = 40, maxval = 255;
            threImg = mat.Threshold(thresh, maxval, ThresholdTypes.Binary);

            //Mat threImg = new Mat();
            //Cv2.AdaptiveThreshold(mat, threImg, 255, AdaptiveThresholdTypes.MeanC, ThresholdTypes.Binary, 33, 20);
            //Cv2.ImShow("自动阈值", threImg);
            mat.Release();
            //膨胀处理
            element = Cv2.GetStructuringElement(MorphShapes.Ellipse,new Size(15,15));
            DilateImg = threImg.Dilate(element);
            Cv2.ImShow("显示膨胀", DilateImg);
            Cv2.ImWrite("保存膨胀.tiff", DilateImg);
            //threImg.Release();
            //腐蚀处理
            ErodeImg = DilateImg.Erode(element);
            Cv2.ImShow("显示腐蚀", ErodeImg);
            Cv2.ImWrite("保存腐蚀.tiff", ErodeImg);
            //寻找图像轮廓
            OpenCvSharp.Point[][] contours;
            HierarchyIndex[] hierachy;
            Cv2.FindContours(DilateImg, out contours, out hierachy, RetrievalModes.List, ContourApproximationModes.ApproxTC89KCOS);
            threImg.Release();
            DilateImg.Release();


            //根据找到的轮廓点，拟合椭圆
            for (int j = 0; j < contours.Length; j++) {
                //拟合函数必须至少5个点，少于则不拟合
                if (contours[j].Length < 5) continue;
                //椭圆拟合
                var rrt = Cv2.FitEllipse(contours[j]);
                if (rrt.Size.Width > 20 && rrt.Size.Height > 20) {
                    //imageShows[imageShows.Count - 1].AddCrossLine(rrt);
                    strLog +=  rrt.Center.X.ToString("0.00") + "," + rrt.Center.Y.ToString("0.00") + "\r\n";
                }
            }
            contours = null;
            hierachy = null;
            System.GC.Collect();
            System.GC.WaitForPendingFinalizers();
        }