using Emgu.CV;
using Emgu.CV.CvEnum;
using Emgu.CV.Structure;
using System.Drawing;
using System.Windows.Forms;

public void CutRectangleImage(string imagePath)
{Image<Bgr, Byte> src = new Image<Bgr, byte>(imagePath);int scale = 1;if (src.Width > 500){scale = 2;}if (src.Width > 1000){scale = 10;}if (src.Width > 10000){scale = 100;}var size = new Size(src.Width / scale, src.Height / scale);Image<Bgr, Byte> srcNewSize = new Image<Bgr, byte>(size);CvInvoke.Resize(src, srcNewSize, size);//将图像转换为灰度UMat grayImage = new UMat(); CvInvoke.CvtColor(srcNewSize, grayImage, ColorConversion.Bgr2Gray);//使用高斯滤波去除噪声CvInvoke.GaussianBlur(grayImage, grayImage, new Size(3, 3), 3);UMat cannyEdges = new UMat();CvInvoke.Canny(grayImage, cannyEdges, 60, 180);//通过边缘化，然后取出轮廓#region 取三角形和矩形的顶点坐标List<Triangle2DF> triangleList = new List<Triangle2DF>();List<RotatedRect> boxList = new List<RotatedRect>(); //旋转的矩形框
​using (VectorOfVectorOfPoint contours = new VectorOfVectorOfPoint()){CvInvoke.FindContours(cannyEdges, contours, null, RetrType.List, ChainApproxMethod.ChainApproxSimple);int count = contours.Size;for (int i = 0; i < count; i++){using (VectorOfPoint contour = contours[i])using (VectorOfPoint approxContour = new VectorOfPoint()){CvInvoke.ApproxPolyDP(contour, approxContour, CvInvoke.ArcLength(contour, true) * 0.08, true);//仅考虑面积大于50的轮廓if (CvInvoke.ContourArea(approxContour, false) > 50){if (approxContour.Size == 3) //轮廓有3个顶点：三角形{System.Drawing.Point[] pts = approxContour.ToArray();triangleList.Add(new Triangle2DF(pts[0], pts[1], pts[2]));}else if (approxContour.Size == 4) //轮廓有4个顶点{#region 检测角度，如果角度都在 [80, 100] 之间，则为矩形bool isRectangle = true;System.Drawing.Point[] pts = approxContour.ToArray();LineSegment2D[] edges = Emgu.CV.PointCollection.PolyLine(pts, true);
​for (int j = 0; j < edges.Length; j++){double angle = Math.Abs(edges[(j + 1) % edges.Length].GetExteriorAngleDegree(edges[j]));if (angle < 80 || angle > 100){isRectangle = false;break;}}#endregionif (isRectangle) boxList.Add(CvInvoke.MinAreaRect(approxContour));}}}}}#endregion#region 保存剪切的最大的矩形图片  Rectangle rectangle = new Rectangle(0, 0, src.Width, src.Height);int maxWidth = 0;//boxList = boxList.Where(p => p.Size.Width > 300).ToList();for (int i = 0; i < boxList.Count(); i++){RotatedRect box = boxList[i];Rectangle rectangleTemp = box.MinAreaRect();//这里对取到的顶点坐标进行了加宽，因为矩形可能存在角度，这里没有进行角度旋转，所以加宽了取值范围就可以取到完整的图了rectangleTemp = new Rectangle(rectangleTemp.X * scale, rectangleTemp.Y * scale, rectangleTemp.Width * scale + scale, rectangleTemp.Height * scale + scale);//取最大的矩形图片if (rectangleTemp.Width > maxWidth){maxWidth = rectangleTemp.Width;rectangle = rectangleTemp;}}src.Draw(rectangle, new Bgr(System.Drawing.Color.Red), 4);//在图片中画线CvInvoke.Imwrite("原始图片.bmp", src); //保存原始图片CvInvoke.cvSetImageROI(src.Ptr, rectangle);//设置兴趣点—ROI(region of interest )var clone = src.Clone(); CvInvoke.Imwrite("剪切的矩形图片.bmp", clone); //保存结果图  #endregionsrc.Dispose();srcNewSize.Dispose();grayImage.Dispose();
}

private void btnRectangle_Click(object sender, RoutedEventArgs e)
{System.Windows.Forms.OpenFileDialog frm = new System.Windows.Forms.OpenFileDialog();frm.Filter = "(*.jpg,*.png,*.jpeg,*.bmp,*.gif)|*.jgp;*.png;*.jpeg;*.bmp;*.gif|All files(*.*)|*.*";if (frm.ShowDialog() == System.Windows.Forms.DialogResult.OK){CutRectangleImage(frm.FileName);}
}

public void CutCircleImage(string imagePath)
{ Image<Bgr, Byte> src = new Image<Bgr, byte>(imagePath);int scale = 1;if (src.Width > 500){scale = 2;}if (src.Width > 1000){scale = 10;}if (src.Width > 10000){scale = 100;} var size = new Size(src.Width / scale, src.Height / scale);Image<Bgr, Byte> srcNewSize = new Image<Bgr, byte>(size);CvInvoke.Resize(src, srcNewSize, size);//将图像转换为灰度UMat grayImage = new UMat();CvInvoke.CvtColor(srcNewSize, grayImage, ColorConversion.Bgr2Gray); //使用高斯滤波去除噪声CvInvoke.GaussianBlur(grayImage, grayImage, new Size(3, 3), 3); //霍夫圆检测CircleF[] circles = CvInvoke.HoughCircles(grayImage, HoughModes.Gradient, 2.0, 200.0, 100.0, 180.0, 5);Rectangle rectangle = new Rectangle();float maxRadius = 0;foreach (CircleF circle in circles){var center = circle.Center;//圆心var radius = circle.Radius;//半径if (radius > maxRadius){maxRadius = radius;rectangle = new Rectangle((int)(center.X - radius) * scale,(int)(center.Y - radius) * scale,(int)radius * 2 * scale + scale,(int)radius * 2 * scale + scale);}srcNewSize.Draw(circle, new Bgr(System.Drawing.Color.Blue), 4);
​}CvInvoke.Imwrite("原始图片.bmp", srcNewSize); //保存原始图片if (maxRadius == 0){MessageBox.Show("没有圆形");}CvInvoke.cvSetImageROI(srcNewSize.Ptr, rectangle);//设置兴趣点—ROI(region of interest )var clone = srcNewSize.Clone();CvInvoke.Imwrite("剪切的圆形图片.bmp", clone); //保存结果图  src.Dispose();srcNewSize.Dispose();grayImage.Dispose();
}