文章目錄

• 一、前文
• 二、算法流程
• 三、界面布局
• 四、功能實(shí)現(xiàn)
• • 4.1 打開圖片
  • 4.2 HoughLinesP直線提取—源碼
  • 4.3 HoughLinesP直線提取—參數(shù)講解
• 五、運(yùn)行效果圖
• 六、參考

一、前文

Hough變換
經(jīng)典的直線檢測(cè)算法

二、算法流程

高斯模糊

Canny邊緣檢測(cè)

HoughLinesP直線尋找，直線提取

三、界面布局

• 一個(gè)Label
• N個(gè)Button
• 三個(gè)Picture

四、功能實(shí)現(xiàn)

4.1 打開圖片

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直線提取—源碼

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直線提取—參數(shù)講解

// // 摘要: // Finds lines segments in a binary image using probabilistic Hough transform. // // 參數(shù): // 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] // // 返回結(jié)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);

• image，灰度圖片輸入
• rho，步長(zhǎng)為1的半徑
• theta，步長(zhǎng)為π/180的角來(lái)，來(lái)搜索所有可能的直線
• threshold，閾值，大于閾值 threshold 的線段才可以被確認(rèn)為直線。該值越小，判定出的直線越多；值越大，判定出的直線就越少。
• minLineLength，線段的最短長(zhǎng)度，長(zhǎng)度小于該值的線段會(huì)被忽略
• maxLineGap，兩條線段之間的最大間隔，間隔小于該值的兩條線會(huì)被當(dāng)成一條線

五、運(yùn)行效果圖

從左到右

• 第一張是原圖
• 第二張是高斯模糊的結(jié)果圖
• 第三張是HoughLinesP直線提取的結(jié)果圖

六、參考

OpenCV—直線檢測(cè)

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