c#中WinForm使用OpencvSharp4实现简易抓边

环境： VS2019 ， OpencvSharp4 4.5.5.20211231 ， .NET Framework 4.8

界面设计:

图像显示用的是picturebox 控件都是windows基本控件

效果展示:

图像是自己画图画的 所以抓的效果比较好 。其他图片的话可能需要调整一下相关参数，效果可能达不到这么好

实现原理： 在图像中选择ROI，从原图上把对应ROI部分的图像扣下来，然后对扣下来的图像进行边缘处理等操作，得到边缘和拟合线，最后在原图上将边缘和拟合线画出来即可。注意，得到的边缘是相对于ROI区域的坐标，需要转化成相对于原图的坐标才行，只需加上ROI的坐标即可。

主要部分代码:

定义的ROI类 注意一下四个点的相对位置

    public class ROI
    {
        // 四个点的顺序关系
        //  1---2
        //  |   |
        //  3---4
        public OpenCvSharp.Point FirstPoint { get; set; } = new OpenCvSharp.Point(0, 0);
        public OpenCvSharp.Point SecondPoint { get; set; } = new OpenCvSharp.Point(0, 0);
        public OpenCvSharp.Point ThirdPoint { get; set; } = new OpenCvSharp.Point(0, 0);
        public OpenCvSharp.Point FourthPoint { get; set; } = new OpenCvSharp.Point(0, 0);

        public OpenCvSharp.Point2f Center
        {
            get
            {
                OpenCvSharp.Point2f center = new OpenCvSharp.Point2f();
                center.X = (float)((FirstPoint.X + SecondPoint.X + ThirdPoint.X + FourthPoint.X) / 4.0);
                center.Y = (float)((FirstPoint.Y + SecondPoint.Y + ThirdPoint.Y + FourthPoint.Y) / 4.0);
                return center;
            }
        }

        public OpenCvSharp.Size2f Size
        {
            get
            {
                return new OpenCvSharp.Size2f(Width, Height);
            }
        }
        public int XLeft
        {
            get { return FirstPoint.X; }
        }
        public int YTop
        {
            get { return FirstPoint.Y; }
        }
        public int XRight
        {
            get { return FourthPoint.X; }
        }
        public int YBottom
        {
            get { return FourthPoint.Y; }
        }

        public double Width
        {
            get { return FourthPoint.X - FirstPoint.X; }
        }
        public double Height
        {
            get { return FourthPoint.Y - FirstPoint.Y; }
        }

        public void Reset()
        {
            FirstPoint = new OpenCvSharp.Point(0, 0);
            SecondPoint = new OpenCvSharp.Point(0, 0);
            ThirdPoint = new OpenCvSharp.Point(0, 0);
            FourthPoint = new OpenCvSharp.Point(0, 0);
        }

        // 四个点全为0 则判断为空
        public bool IsNull()
        {
            bool en = true;
            en = en && FirstPoint == new OpenCvSharp.Point(0, 0);
            en = en && SecondPoint == new OpenCvSharp.Point(0, 0);
            en = en && ThirdPoint == new OpenCvSharp.Point(0, 0);
            en = en && FourthPoint == new OpenCvSharp.Point(0, 0);
            return en;
        }

        public OpenCvSharp.Point2f[] GetCoutonrs2f()
        {
            OpenCvSharp.Point2f[] coutonrs = new OpenCvSharp.Point2f[4];
            coutonrs[0] = FirstPoint;
            coutonrs[1] = SecondPoint;
            coutonrs[2] = FourthPoint;
            coutonrs[3] = ThirdPoint;
            return coutonrs;
        }

        public OpenCvSharp.Point[] GetCoutonrs()
        {
            OpenCvSharp.Point[] coutonrs = new OpenCvSharp.Point[4];
            coutonrs[0] = FirstPoint;
            coutonrs[1] = SecondPoint;
            coutonrs[2] = FourthPoint;
            coutonrs[3] = ThirdPoint;
            return coutonrs;
        }
    }

相关变量:

    public enum eDirections  // ROI移动方向
    {
        NULL = 0,
        上 = 1,
        下 = 2,
        左 = 3,
        右 = 4
    }

    //ROI大小调整方式
    public enum eResizeMode
    {
        All = 0, // 长宽一起调整
        Width = 1, // 只变宽度 即 矩形的长
        Height = 2, //  只变高度 即 矩形的宽
    }

    public class yVars
    {
        public static string OriImg; // 原图

        public static bool IsDrawEdgeOK = false;
        public static bool pbxMouseDown = false;
        public static bool IsMouseMove = false;
        public static bool IsSelectROIOK = false;
        public static bool IsMouseUp = false;

        public static int step; //ROI区域移动步长
        public static eDirections direct = eDirections.NULL;

        public static int ROINum = 1; // 操作第一个ROI还是第二个ROI
        public static bool IsSelectingROI = false;
        //
        public static bool IsSelectROI_1 = false;
        public static bool IsSelectROI_1_OK = false;

        public static bool IsSelectROI_2 = false;
        public static bool IsSelectROI_2_OK = false;

        public static ROI myROI_1 = new ROI();
        public static ROI myROI_2 = new ROI();
    }

ROI的绘制：

矩形的ROI ，我们只需要两个点就能确定一个矩形。

我们获取到的位置是鼠标相对于picturebox的位置，需要转化成相对于图像的坐标，我的 picturebox 的 sizemode 是 stretchImage ，所以按比例转化过去就行。

在 picturebox 的 mousedown 事件中 记录鼠标按下的第一个位置 为ROI的第一个点。

我把绘制ROI的过程写在 mousemove 事件里面，这样就能实现在确定第一个点后鼠标移动时ROI区域一直显示出来

        private void pbxImgShow_MouseMove(object sender, MouseEventArgs e)
        {
            if (yVars.IsSelectROI_1 == false && yVars.IsSelectROI_2 == false)
                return;
            if (yVars.pbxMouseDown == false)
                return;
            if (yVars.IsMouseUp == true)
                return;
            int mx = 0, my = 0;
            Mat mm = new Mat(yVars.OriImg);
            // 鼠标相对于picturebox的位置
            mx = Frm_Main.Instance.pbxImgShow.PointToClient(Control.MousePosition).X;
            my = Frm_Main.Instance.pbxImgShow.PointToClient(Control.MousePosition).Y;

            // 鼠标移动时 位置在 picturebox 中就画出对应的ROI形状
            if (mx < pbxImgShow.Width && my < pbxImgShow.Height)
            {
                //转成在图片上的位置
                double xx = mx * mm.Width * 1.0 / Frm_Main.Instance.pbxImgShow.Width;
                double yy = my * mm.Height * 1.0 / Frm_Main.Instance.pbxImgShow.Height;

                if (yVars.IsSelectROI_1 == true)
                {
                    yVars.myROI_1.FourthPoint = new OpenCvSharp.Point(xx, yy);
                    yVars.myROI_1.SecondPoint = new OpenCvSharp.Point(xx, yVars.myROI_1.FirstPoint.Y);
                    yVars.myROI_1.ThirdPoint = new OpenCvSharp.Point(yVars.myROI_1.FirstPoint.X, yy);

                    mm = yActions.DrawROIMat(mm, yVars.myROI_1);
                    yVars.IsSelectROI_1_OK = true;
                }
                else if (yVars.IsSelectROI_2 == true)
                {
                    yVars.myROI_2.FourthPoint = new OpenCvSharp.Point(xx, yy);
                    yVars.myROI_2.SecondPoint = new OpenCvSharp.Point(xx, yVars.myROI_2.FirstPoint.Y);
                    yVars.myROI_2.ThirdPoint = new OpenCvSharp.Point(yVars.myROI_2.FirstPoint.X, yy);
                    mm = yActions.DrawROIMat(mm, yVars.myROI_2);
                    yVars.IsSelectROI_2_OK = true;
                }
                yVars.IsMouseMove = true;
            }
            else // 释放鼠标时的点位不在picturebox中 将相关变量值清空
            {
                if (yVars.IsSelectROI_1 == true)
                {
                    yVars.myROI_1.Reset();

                    yVars.IsSelectROI_1_OK = false;
                }
                else if (yVars.IsSelectROI_2 == true)
                {
                    yVars.myROI_2.Reset();
                    yVars.IsSelectROI_2_OK = false;
                }
            }
            pbxImgShow.Image = yImgConvert.MatToBitmap(mm);
            mm.Release();
        }

在线程或者循环等过程中定义的 mat 要及时 Release 掉。

在 mouseup 事件中就绘制完成了 注意选择的第一点和第二点，分别是ROI的 FirstPoint 和 FourthPoint  ，两点的相对位置要确定好，要保证 FirstPoint 为左上角的点 FourthPoint 为右下角的点，不是的话 就对 FirstPoint 和 FourthPoint 重新赋值， FirstPoint 为两点的 x , y 最小的点 ，FourthPoint  为两点的 x , y 最大的点。

绘制完ROI后可以对其位置和大小进行相应的调整。

        public static Mat DrawROIMat(Mat src, ROI rOI, Scalar? scalar = null, int thickness = 1, LineTypes lineTypes = LineTypes.AntiAlias)
        {
            Scalar sc = scalar ?? Scalar.Red;
            Cv2.Line(src, rOI.FirstPoint, rOI.SecondPoint, sc, thickness, lineTypes);
            Cv2.Line(src, rOI.SecondPoint, rOI.FourthPoint, sc, thickness, lineTypes);
            Cv2.Line(src, rOI.FourthPoint, rOI.ThirdPoint, sc, thickness, lineTypes);
            Cv2.Line(src, rOI.ThirdPoint, rOI.FirstPoint, sc, thickness, lineTypes);
            return src;
        }

对位置进行调整： 主要思想就是对ROI的四个点的坐标相应方向进行加减即可,主要超限问题即可。

        public static void ImgROIMove(Mat src, out Mat dstImg, ref ROI rOI, eDirections eDirections, double step, int gap = 3)
        {
            dstImg = new Mat();

            switch (eDirections)
            {
                case eDirections.NULL:
                    break;
                case eDirections.上:
                    if (rOI.YTop - step <= gap)
                    {
                        rOI.ThirdPoint = new OpenCvSharp.Point(rOI.ThirdPoint.X, rOI.ThirdPoint.Y - rOI.YTop + gap);
                        rOI.FourthPoint = new OpenCvSharp.Point(rOI.FourthPoint.X, rOI.FourthPoint.Y - rOI.YTop + gap);
                        rOI.FirstPoint = new OpenCvSharp.Point(rOI.FirstPoint.X, gap);
                        rOI.SecondPoint = new OpenCvSharp.Point(rOI.SecondPoint.X, gap);
                    }
                    else
                    {
                        rOI.FirstPoint = new OpenCvSharp.Point(rOI.FirstPoint.X, rOI.FirstPoint.Y - step);
                        rOI.SecondPoint = new OpenCvSharp.Point(rOI.SecondPoint.X, rOI.SecondPoint.Y - step);
                        rOI.ThirdPoint = new OpenCvSharp.Point(rOI.ThirdPoint.X, rOI.ThirdPoint.Y - step);
                        rOI.FourthPoint = new OpenCvSharp.Point(rOI.FourthPoint.X, rOI.FourthPoint.Y - step);
                    }
                    break;
                case eDirections.下:
                    if (rOI.YBottom + step >= src.Height - gap)
                    {
                        rOI.FirstPoint = new OpenCvSharp.Point(rOI.FirstPoint.X, rOI.FirstPoint.Y + src.Height - rOI.YBottom - gap);
                        rOI.SecondPoint = new OpenCvSharp.Point(rOI.SecondPoint.X, rOI.SecondPoint.Y + src.Height - rOI.YBottom - gap);
                        rOI.ThirdPoint = new OpenCvSharp.Point(rOI.ThirdPoint.X, src.Height - gap);
                        rOI.FourthPoint = new OpenCvSharp.Point(rOI.FourthPoint.X, src.Height - gap);
                    }
                    else
                    {
                        rOI.FirstPoint = new OpenCvSharp.Point(rOI.FirstPoint.X, rOI.FirstPoint.Y + step);
                        rOI.SecondPoint = new OpenCvSharp.Point(rOI.SecondPoint.X, rOI.SecondPoint.Y + step);
                        rOI.ThirdPoint = new OpenCvSharp.Point(rOI.ThirdPoint.X, rOI.ThirdPoint.Y + step);
                        rOI.FourthPoint = new OpenCvSharp.Point(rOI.FourthPoint.X, rOI.FourthPoint.Y + step);
                    }
                    break;
                case eDirections.左:
                    if (rOI.XLeft - step <= gap)
                    {
                        rOI.SecondPoint = new OpenCvSharp.Point(rOI.SecondPoint.X - rOI.XLeft + gap, rOI.SecondPoint.Y);
                        rOI.FourthPoint = new OpenCvSharp.Point(rOI.FourthPoint.X - rOI.XLeft + gap, rOI.FourthPoint.Y);
                        rOI.ThirdPoint = new OpenCvSharp.Point(gap, rOI.ThirdPoint.Y);
                        rOI.FirstPoint = new OpenCvSharp.Point(gap, rOI.FirstPoint.Y);
                    }
                    else
                    {
                        rOI.FirstPoint = new OpenCvSharp.Point(rOI.FirstPoint.X - step, rOI.FirstPoint.Y);
                        rOI.SecondPoint = new OpenCvSharp.Point(rOI.SecondPoint.X - step, rOI.SecondPoint.Y);
                        rOI.ThirdPoint = new OpenCvSharp.Point(rOI.ThirdPoint.X - step, rOI.ThirdPoint.Y);
                        rOI.FourthPoint = new OpenCvSharp.Point(rOI.FourthPoint.X - step, rOI.FourthPoint.Y);
                    }
                    break;
                case eDirections.右:
                    if (rOI.XRight + step >= src.Width - gap)
                    {
                        rOI.FirstPoint = new OpenCvSharp.Point(rOI.FirstPoint.X + src.Width - rOI.XRight - gap, rOI.FirstPoint.Y);
                        rOI.ThirdPoint = new OpenCvSharp.Point(rOI.ThirdPoint.X + src.Width - rOI.XRight - gap, rOI.ThirdPoint.Y);
                        rOI.FourthPoint = new OpenCvSharp.Point(src.Width - gap, rOI.FourthPoint.Y);
                        rOI.SecondPoint = new OpenCvSharp.Point(src.Width - gap, rOI.SecondPoint.Y);
                    }
                    else
                    {
                        rOI.FirstPoint = new OpenCvSharp.Point(rOI.FirstPoint.X + step, rOI.FirstPoint.Y);
                        rOI.SecondPoint = new OpenCvSharp.Point(rOI.SecondPoint.X + step, rOI.SecondPoint.Y);
                        rOI.ThirdPoint = new OpenCvSharp.Point(rOI.ThirdPoint.X + step, rOI.ThirdPoint.Y);
                        rOI.FourthPoint = new OpenCvSharp.Point(rOI.FourthPoint.X + step, rOI.FourthPoint.Y);
                    }
                    break;
                default:
                    break;
            }
            dstImg = yActions.DrawROIMat(src, rOI);
        }

对大小进行调整： 主要思路是 ROI 大小调整前后，其中心点坐标不变，相应的长度和宽度变了。我们就可以采用 OpenCvSharp.RotatedRect 这个类，根据 中心点坐标，相应size，和倾斜角度(正矩形为0). 最后再把 RotatedRect 的四个顶点重新赋值给 ROI的四个顶点就好，注意一下点的相对位置关系。

        public static void ImgROIResize(Mat src, out Mat dstImg, ref ROI rOI, bool IsAdd, double step, eResizeMode eResizeMode)
        {
            dstImg = new Mat();
            double height = rOI.Height, width = rOI.Width;
            if (IsAdd == true)
            {
                switch (eResizeMode)
                {
                    case eResizeMode.All:
                        height = rOI.Height + step;
                        width = rOI.Width + step;
                        break;
                    case eResizeMode.Width:
                        width = rOI.Width + step;
                        break;
                    case eResizeMode.Height:
                        height = rOI.Height + step;
                        break;
                }
            }
            else
            {
                switch (eResizeMode)
                {
                    case eResizeMode.All:
                        height = rOI.Height - step;
                        width = rOI.Width - step;
                        break;
                    case eResizeMode.Width:
                        width = rOI.Width - step;
                        break;
                    case eResizeMode.Height:
                        height = rOI.Height - step;
                        break;
                }
            }

            OpenCvSharp.Size2f size = new Size2f(width, height);
            OpenCvSharp.RotatedRect rotateRect = new RotatedRect(rOI.Center, size, 0);
            Point2f[] points = rotateRect.Points();// 获得矩形四个顶点坐标
            // 大小缩放后需要判断坐标是否超限
            for (int i = 0; i < points.Length; i++)
            {
                if (points[i].X <= 0 || points[i].Y <= 0 || points[i].X >= src.Width || points[i].Y >= src.Height)
                {
                    return;
                }
            }
            rOI.FirstPoint = new OpenCvSharp.Point(points[1].X, points[1].Y);
            rOI.SecondPoint = new OpenCvSharp.Point(points[2].X, points[2].Y);
            rOI.ThirdPoint = new OpenCvSharp.Point(points[0].X, points[0].Y);
            rOI.FourthPoint = new OpenCvSharp.Point(points[3].X, points[3].Y);
            dstImg = yActions.DrawROIMat(src, rOI);
        }

绘制并调整好ROI后，从原图上将对应的ROI图像扣下来，

        public static Mat GetROIMat(Mat mm, ROI rOI)
        {
            Mat mask = Mat.Zeros(mm.Size(), MatType.CV_8UC1);
            List<List<OpenCvSharp.Point>> pp = new List<List<OpenCvSharp.Point>>() {
               rOI.GetCoutonrs().ToList()
            };
            Cv2.FillPoly(mask, pp, new Scalar(255, 255, 255));
            OpenCvSharp.Rect rect = Cv2.BoundingRect(rOI.GetCoutonrs2f());
            if (rect.X <= 0) rect.X = 1;
            if (rect.Y <= 0) rect.Y = 0;
            if (rect.X + rect.Width > mm.Width)
                rect.Width = mm.Width - rect.X - 1;
            if (rect.Y + rect.Height > mm.Height)
                rect.Height = mm.Height - rect.Y - 1;
            Mat src = new Mat(mm, rect);
            Mat maskROI = new Mat(mask, rect);
            Mat dstImg = new Mat();
            Cv2.BitwiseAnd(src, src, dstImg, maskROI);
            return dstImg;
        }

然后对每张扣下来的mat进行边缘检测 抓边拟合等操作

部分代码

            coutonrs = yVars.myROI_1.GetCoutonrs2f();
            srcROIImg = yActions.GetROIMat(src, yVars.myROI_1);
            Cv2.CvtColor(srcROIImg, grayImg, ColorConversionCodes.RGB2GRAY);
            Cv2.Blur(grayImg, grayImg, new OpenCvSharp.Size(3, 3));
            Cv2.Canny(grayImg, cannyImg, param1, param2, param3, true);
            //获得轮廓
            Cv2.FindContours(cannyImg, out contoursROI1, out hierarchly, RetrievalModes.Tree, ContourApproximationModes.ApproxSimple, new OpenCvSharp.Point(0, 0));

            if (contoursROI1.Length == 0)
            {
                YXH._01.yMessagebox.ShowDialogCN("ROI_1未抓到边,请调整迟滞参数,或重新选择ROI区域");
                return;
            }
            // 获取轮廓后需要将点的坐标转换到原图上 此时的坐标是相对于ROI区域的坐标
            // 即每个坐标需要加上ROI区域的左上角坐标 再将转化后的坐标添加进拟合集合内
            for (int i = 0; i < contoursROI1.Length; i++)
            {
                for (int j = 0; j < contoursROI1[i].Length; j++)
                {
                    contoursROI1[i][j] += yVars.myROI_1.FirstPoint;
                    ROI_1_Points.Add(contoursROI1[i][j]);
                    AllPoints.Add(contoursROI1[i][j]);
                }
            }

操作完成后再根据想要在界面上显示的进行相应的绘制即可。

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