0.12-OpenCvSharp4霍夫变换检测直线

0.12 OpenCvSharp4霍夫变换检测直线

// // 摘要: // Finds lines in a binary image using standard Hough transform. // // 参数: // image: 输入八位，单通道，二值图像 // The 8-bit, single-channel, binary source image. The image may be modified by // the function // // rho: // Distance resolution of the accumulator in pixels 累加器的距离分辨率，以像素为单位 // // theta: // Angle resolution of the accumulator in radians 累加器的角度分辨率(以弧度为单位) // // threshold: 阈值 // The accumulator threshold parameter. Only those lines are returned that get enough // votes ( > threshold ) // // srn: // For the multi-scale Hough transform it is the divisor for the distance resolution // rho. [By default this is 0] // // stn: // For the multi-scale Hough transform it is the divisor for the distance resolution // theta. [By default this is 0] // // 返回结果: 直线的输出向量。每条线都由一个二元向量表示。是到坐标原点(0,0)(图像的左上角)的距离，是以弧度表示的直线旋转角度 // The output vector of lines. Each line is represented by a two-element vector // (rho, theta) . rho is the distance from the coordinate origin (0,0) (top-left // corner of the image) and theta is the line rotation angle in radians public static LineSegmentPolar[] HoughLines(InputArray image, double rho, double theta, int threshold, double srn = 0, double stn = 0); // // 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:输出线。每条线由一个4元向量(x1, y1, x2, y2)表示。 // 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);

检测步骤： 1）读入图像，灰度变换。 2）阈值二值化。 3）Canny 边缘提取。 4）霍夫变换检测直线。 实现：

Mat pLine = Cv2.ImRead("D:\\OpenCV\\Topencv\\CsharpOpenCv\\CsharpOpenCv\\3.png"); Cv2.ImShow("Line",pLine); Mat pGray = new Mat(pLine.Size(),pLine.Type()); // 霍夫直线 canny边缘提取 --> cvtcolor转灰度 --> HoughLinesP霍夫边缘检测 // 灰度变换 Cv2.CvtColor(pLine, pGray, ColorConversionCodes.RGB2GRAY); // 阈值二值化 Mat pThresholdImage = new Mat(pLine.Size(), pLine.Type()); Cv2.Threshold(pGray, pThresholdImage, 100, 255, ThresholdTypes.Binary); // Canny 边缘提取 Mat pCannyImage = new Mat(pLine.Size(), pLine.Type()); Cv2.Canny(pThresholdImage, pCannyImage, 20, 50, 3); // 霍夫变换检测直线 LineSegmentPoint[] lineSegmentPoint; //检测直线的端点的集合。LineSegmentPoint lineSegmentPoint = Cv2.HoughLinesP(pCannyImage, 1.0, Cv2.PI / 180, 200, 50, 20); // 转换为BGR图，为后面输出彩线 Cv2.CvtColor(pCannyImage, pCannyImage, ColorConversionCodes.GRAY2BGR); Scalar pLcolor = new Scalar(0, 255, 0); //绿色 BGR for (int i = 0; i < lineSegmentPoint.Length; i++) { Cv2.Line(pCannyImage, lineSegmentPoint[i].P1, lineSegmentPoint[i].P2, pLcolor, 1); //依据点集画线 } Cv2.ImShow("检测直线",pCannyImage);

参考： OpenCv–霍夫直线变换(检测直线)