一、前文

Hough变换经典的直线检测算法

二、算法流程

高斯模糊
Canny边缘检测
HoughLinesP直线寻找，直线提取

三、界面布局

一个Label
N个Button
三个Picture

在这里插入图片描述

四、功能实现

4.1 打开图片

 private void openFileBtn_Click(object sender, EventArgs e)
 {
     OpenFileDialog openfiledialog = new OpenFileDialog();
     openfiledialog.Filter = "PNG Files (*.png)|*.png|JPG Files (*.jpg)|*.jpg|GIF Files (*.gif)|*.gif";
     openfiledialog.RestoreDirectory = true;
     if (openfiledialog.ShowDialog() == DialogResult.OK)
     {
         Console.WriteLine(openfiledialog.FileName);
         fileName = openfiledialog.FileName;

         //Mat src = new Mat("foo.png", LoadMode.Color);
         Mat src = new Mat(fileName);
         //Mat src = new Mat(fileName, ImreadModes.Color);
         var frameBitmap = BitmapConverter.ToBitmap(src);

         pictureBox1.Image?.Dispose();
         pictureBox1.Image = frameBitmap;
     }
 }

4.2 HoughLinesP直线提取—源码

private void houghLinesBtn_Click(object sender, EventArgs e)
{
    cannyBtn_Click(sender, e);
    mOutput = new Mat(mInput.Rows, mInput.Cols, MatType.CV_8UC4);
    mInput.CopyTo(mOutput);

    double rho = 1;
    double theta = 1;
    int threshold = 10;
    double minLineLength = 0;
    double maxLineGap = 0;

    var res = Cv2.HoughLinesP(edges,
        rho: rho,
        theta: theta / 100.0,
        threshold: threshold,
        minLineLength: minLineLength,
        maxLineGap: maxLineGap);

    for (int i = 0; i < res.Length; i++)
    {
        Scalar color = Scalar.RandomColor();
        Cv2.Line(mOutput, res[i].P1, res[i].P2,
            color: color,
            thickness: 2,
            lineType: LineTypes.Link8);
    }

    srcPictureBox.Image = BitmapConverter.ToBitmap(mInput);
    grayPictureBox.Image = BitmapConverter.ToBitmap(edges);
    dstPictureBox.Image = BitmapConverter.ToBitmap(mOutput);
}

4.3 HoughLinesP直线提取—参数讲解

//
// 摘要:
//     Finds lines segments in a binary image using probabilistic Hough transform.
//
// 参数:
//   image:
//
//   rho:
//     Distance resolution of the accumulator in pixels
//
//   theta:
//     Angle resolution of the accumulator in radians
//
//   threshold:
//     The accumulator threshold parameter. Only those lines are returned that get enough
//     votes ( > threshold )
//
//   minLineLength:
//     The minimum line length. Line segments shorter than that will be rejected. [By
//     default this is 0]
//
//   maxLineGap:
//     The maximum allowed gap between points on the same line to link them. [By default
//     this is 0]
//
// 返回结果:
//     The output lines. Each line is represented by a 4-element vector (x1, y1, x2,
//     y2)
public static LineSegmentPoint[] HoughLinesP(InputArray image, double rho, double theta, int threshold, double minLineLength = 0, double maxLineGap = 0);