C#：边界跟踪法

• EmguCV是将opencv封装的一个.net库，可以被VC++,VC#,VB.net调用。
  EmguCV可以很好地连接C#与opencv，能够弥补opencv在gui这方面的不足。

一、Mat对象的像素操作

• 生成一个m8相同大小的全白图像

            Scalar scalar = new Scalar(255, 255,255);
            Mat coutour_img = new Mat(m8.Size(),MatType.CV_8UC1,scalar);

• Mat中不管是以At访问还是ptr访问，都是行优先 ，先Y轴后X轴（即先行后列）

二、边界跟踪法

• 边界跟踪法的函数

       #region 轮廓追踪
        protected void TraceContour(Mat imagedata,Mat contour_img)
        {
            int hei = imagedata.Rows;
            int wid = imagedata.Cols;
            int cn = imagedata.Channels(); //获取通道数
            int start_i = 0;
            int start_j = 0;

            List<OpenCvSharp.Point> ContourPoints = new List<OpenCvSharp.Point>();
            //寻找种子点
            bool bfindstartpoint = false;
            for (int row = 0; row < hei; row++)
                for (int col = 0; col < wid; col++)
                {
                    if (cn == 1) //如果是单通道
                    {
                        byte p = imagedata.At<byte>(row, col); //获取像素                                                             
                        if (p == 0)
                        {
                            bfindstartpoint = true;
                            start_i = row;
                            start_j = col;
                            break;
                        }
                    }
                }
            uiTextBox1.AppendText("i=" + start_i.ToString());
            uiTextBox1.AppendText(",\t\n j=" + start_j.ToString());

            //搜索方向
            /*
             * 0 1 2
             * 7 + 3
             * 6 5 4
             */
            OpenCvSharp.Point pt = new OpenCvSharp.Point();
            if (bfindstartpoint)
            {
                pt.X = start_i;
                pt.Y = start_j;
                contour_img.Set(pt.X, pt.Y, 0);
            }
            int[,] direction = new int[8, 2] { { -1, +1 }, { 0, +1 }, { +1, +1 }, { +1, 0 }, { +1, -1 }, { 0, -1 }, { -1, -1 }, { -1, 0 } };
            int begindirect = 0;//从0开始顺时针搜索
            int findstart = 0;
            int cur_i = start_i;
            int cur_j = start_j;
            int findpoint = 0;
            int i, j;

            while (findstart == 0)
            {
                findpoint = 0;
                while (findpoint == 0)
                {
                    i = cur_i + direction[begindirect, 1];
                    j = cur_j + direction[begindirect, 0];
                    System.IO.File.AppendAllText("d:/my_trace.txt", "\t\n i=" + i.ToString() + ",j=" + j.ToString(), Encoding.Default);
                    if (j> wid) { return; }
                    byte p = imagedata.At<byte>(i, j); //获取像素   
                    if (p == 0)
                    {
                        findpoint = 1;
                        cur_i = i;
                        cur_j = j;
                        if ((cur_i == start_i) && (cur_j == start_j))  findstart = 1;                   
                        contour_img.Set(cur_i, cur_j, 0);
                        begindirect -= 1;
                        if (begindirect == -1) begindirect = 7;
                        begindirect -= 1;
                        if (begindirect == -1) begindirect = 7;

                    }
                    else
                    {
                        begindirect += 1;
                        if (begindirect == 8) begindirect = 0;
                    }
                }
            }
        }
    }
    #endregion

三、调用

       private void uiButton8_Click(object sender, EventArgs e)
        {
            // 1) 读入彩色图像
            // 2) 彩色图像灰度化
            // 3) 图像二值化 uiButton6_Click 结果在dst
            // 4）边界跟踪 结果在coutour_img
            Mat m8 = new Mat();
            dst.CopyTo(m8);
            Scalar scalar = new Scalar(255, 255,255);
            Mat coutour_img = new Mat(m8.Size(),MatType.CV_8UC1,scalar);
            TraceContour(m8,coutour_img);
            picBoxShowDel.Image = m8.ToBitmap();
            pictureBox1.Image = coutour_img.ToBitmap();
        }