EmguCV方形答题卡识别_emgucv答题卡识别

参考：https://www.cnblogs.com/jsxyhelu/

经过一段时间的学习，终于能利用C#结合EmguCv对简单的答题卡进行识别，样图如下：

最终效果图：

三个imageBox控件

ib_original.SizeMode = PictureBoxSizeMode.Zoom;
            ib_original.FunctionalMode = Emgu.CV.UI.ImageBox.FunctionalModeOption.Minimum;
 
            ib_middle.SizeMode = PictureBoxSizeMode.Zoom;
            ib_middle.FunctionalMode = Emgu.CV.UI.ImageBox.FunctionalModeOption.Minimum;
 
            ib_result.SizeMode = PictureBoxSizeMode.Zoom;
            ib_result.FunctionalMode = Emgu.CV.UI.ImageBox.FunctionalModeOption.Minimum;

主程序代码：（对准考证、答题区域分别测量参考像素值）

if (ib_original.Image != null)
            {
                Mat src = new Image<Bgr, byte>(ib_original.Image.Bitmap).Mat;
 
                //1.获取当前图像的最大矩形边界
                VectorOfVectorOfPoint max_contour = commonUse.GetBoundaryOfPic(src);
 
                //2.对图像进行矫正
                Mat mat_Perspective = commonUse.MyWarpPerspective(src, max_contour);
                //规范图像大小
                CvInvoke.Resize(mat_Perspective, mat_Perspective, new Size(590, 384), 0, 0, Emgu.CV.CvEnum.Inter.Cubic);
                //3.二值化处理（大于阈值取0，小于阈值取255。其中白色为0，黑色为255)
                Mat mat_threshold = new Mat();
                int myThreshold = Convert.ToInt32(num_threshold.Value);
                CvInvoke.Threshold(mat_Perspective, mat_threshold, myThreshold, 255, Emgu.CV.CvEnum.ThresholdType.BinaryInv);
                //ib_middle.Image = mat_threshold;
 
                //形态学膨胀
                Mat mat_dilate = commonUse.MyDilate(mat_threshold);
                //ib_middle.Image = mat_dilate;
 
                //筛选长宽比大于2的轮廓
                VectorOfVectorOfPoint selected_contours = commonUse.GetUsefulContours(mat_dilate, 1);
                //画出轮廓
                Mat color_mat = commonUse.DrawContours(mat_Perspective, selected_contours);
                ib_middle.Image = color_mat;
 
 
                ib_result.Image = mat_Perspective;
                //准考证号，x=230+26*5,y=40+17*10
                tb_log.Text = commonUse.GetValueAndDrawGrid(ib_result, selected_contours, 230, 26, 5, 40, 17, 10, "准考证号：");
 
                //答题区1-5题，x=8+25*5,y=230+16*4
                tb_log.Text += commonUse.GetValueAndDrawGrid(ib_result, selected_contours, 8, 25, 5, 230, 16, 4, "1-5：");
 
                //答题区6-10题,x=159+25*5,y=230+16*4
                tb_log.Text += commonUse.GetValueAndDrawGrid(ib_result, selected_contours, 159, 25, 5, 230, 16, 4, "6-10：");
 
                //答题区11-15题,x=310+25*5,y=230+16*4
                tb_log.Text += commonUse.GetValueAndDrawGrid(ib_result, selected_contours, 310, 25, 5, 230, 16, 4, "11-15：");
 
                //答题区16-20题,x=461+25*5,y=230+16*4
                tb_log.Text += commonUse.GetValueAndDrawGrid(ib_result, selected_contours, 461, 25, 5, 230, 16, 4, "16-20：");
 
                //答题区21-25题,x=8+25*5,y=312+16*4
                tb_log.Text += commonUse.GetValueAndDrawGrid(ib_result, selected_contours, 8, 25, 5, 312, 16, 4, "21-25：");
 
                //答题区26-30题,x=159+25*5,y=312+16*4
                tb_log.Text += commonUse.GetValueAndDrawGrid(ib_result, selected_contours, 159, 25, 5, 312, 16, 4, "26-30：");
 
                //答题区31-35题,x=310+25*5,y=312+16*4
                tb_log.Text += commonUse.GetValueAndDrawGrid(ib_result, selected_contours, 310, 25, 5, 312, 16, 4, "31-35：");
            }
            else
            {
                MessageBox.Show("请先加载图片");
            }

调用函数代码（自定义CommonUse类）：

/// <summary>
        /// 获取给定图像的最大矩形边界
        /// </summary>
        /// <param name="src"></param>
        /// <returns></returns>
        public VectorOfVectorOfPoin