python - 使用霍夫变换检测矩形图像的线条

Question

我想用霍夫变换检测这个矩形线，

这是 opencv 代码:

import cv2
import numpy as np

img = cv2.imread('C:/Users/hp/rectangles.jpg')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
edges = cv2.Canny(gray,50,150,apertureSize = 3)

lines = cv2.HoughLines(edges,1,np.pi/180,200)
for rho,theta in lines[0]:
    a = np.cos(theta)
    b = np.sin(theta)
    x0 = a*rho
    y0 = b*rho
    x1 = int(x0 + 1000*(-b))
    y1 = int(y0 + 1000*(a))
    x2 = int(x0 - 1000*(-b))
    y2 = int(y0 - 1000*(a))

    cv2.line(img,(x1,y1),(x2,y2),(0,0,255),2)

cv2.imwrite('houghlines3.jpg',img)

但它只检测到一行，我怎样才能检测到所有行？

测试此代码并选择这些参数后:

    import cv2
    import numpy as np


        img = cv2.imread('dave.jpg')
        gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
        edges = cv2.Canny(gray,50,150,apertureSize = 3)
        minLineLength = 100
        maxLineGap = 10
        lines = cv2.HoughLinesP(edges,1,np.pi/180,100,minLineLength,maxLineGap)
        for x1,y1,x2,y2 in lines[0]:
            cv2.line(img,(x1,y1),(x2,y2),(0,255,0),2)

        cv2.imwrite('houghlines5.jpg',img)

我得到了这个结果:

我更改了参数但是没有检测到那一行，我应该如何更改参数才能检测到那一行？

Answer 1

我相信检测矩形线条的更好方法是使用 cv2.findContours()和 Canny 边缘检测。

import cv2

image = cv2.imread('1.jpg')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
canny = cv2.Canny(gray, 130, 255, 1)

cnts = cv2.findContours(canny, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if len(cnts) == 2 else cnts[1]

for c in cnts:
    cv2.drawContours(image,[c], 0, (0,255,0), 3)

cv2.imshow("result", image)
cv2.waitKey(0)