import cv2
import numpy as np 

img = cv2.imread('road.jpg') #or use sudoku img
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
edges = cv2.Canny(gray,50,150,apertureSize=3) #50 & 150 are thresold values
cv2.imshow('edges',edges)
lines = cv2.HoughLinesP(edges,1,np.pi/180,100,minLineLength=100,maxLineGap=10)
#last 2 argumengts are diff from hough line

for line in lines:
    x1,y1,x2,y2 = line[0]
    cv2.line(img,(x1,y1),(x2,y2),(0,255,0),2)

cv2.imshow('image',img)
k =cv2.waitKey(0)
cv2.destroyAllWindow()