ch7_2_2

代码说明：

  设定循环检测次数，这里设为只循环一次 tip_l=1 设定hough变换的遍历步径 xl=30 ％设定线段起始点 xr=60 ％设定线段终止点(Set the number of cycle detection, here is set to cycle only once tip_l = 1 set hough transform Path traversal step xl = 30 set line segment starting point xr = 60 set line segment termination point)