可以通过使用Imgproc
类的HoughLines()
方法应用霍夫变换技术来检测给定图像的形状。以下是此方法的语法。
HoughLines(image, lines, rho, theta, threshold)
该方法接受以下参数 -
Mat
对象。Mat
类的一个对象,用于存储存储线的参数(r,Φ)
的向量。double
的变量,以像素为单位表示参数r
的分辨率。double
的变量,表示以弧度表示的参数Φ
的分辨率。示例
下面的程序演示如何检测给定图像中的霍夫线。
package com.zyiz.miscellaneous; import org.opencv.core.Core; import org.opencv.core.Mat; import org.opencv.core.Point; import org.opencv.core.Scalar; import org.opencv.imgcodecs.Imgcodecs; import org.opencv.imgproc.Imgproc; public class HoughlinesTest { public static void main(String args[]) throws Exception { // Loading the OpenCV core library System.loadLibrary( Core.NATIVE_LIBRARY_NAME ); // Reading the Image from the file and storing it in to a Matrix object String file = "F:/worksp/opencv/images/hough_input.jpg"; // Reading the image Mat src = Imgcodecs.imread(file,0); // Detecting edges of it Mat canny = new Mat(); Imgproc.Canny(src, canny, 50, 200, 3, false); // Changing the color of the canny Mat cannyColor = new Mat(); Imgproc.cvtColor(canny, cannyColor, Imgproc.COLOR_GRAY2BGR); // Detecting the hough lines from (canny) Mat lines = new Mat(); Imgproc.HoughLines(canny, lines, 1, Math.PI/180, 100); System.out.println(lines.rows()); System.out.println(lines.cols()); // Drawing lines on the image double[] data; double rho, theta; Point pt1 = new Point(); Point pt2 = new Point(); double a, b; double x0, y0; for (int i = 0; i < lines.cols(); i++) { data = lines.get(0, i); rho = data[0]; theta = data[1]; a = Math.cos(theta); b = Math.sin(theta); x0 = a*rho; y0 = b*rho; pt1.x = Math.round(x0 + 1000*(-b)); pt1.y = Math.round(y0 + 1000*(a)); pt2.x = Math.round(x0 - 1000*(-b)); pt2.y = Math.round(y0 - 1000 *(a)); Imgproc.line(cannyColor, pt1, pt2, new Scalar(0, 0, 255), 6); } // Writing the image Imgcodecs.imwrite("F:/worksp/opencv/images/hough_output.jpg", cannyColor); System.out.println("Image Processed"); } }
假定以下是上述程序中指定的输入图像:sample4.jpg
。
执行上面示例代码,得到以下结果 -