old_contents: #!/usr/bin/python
  
  '''
  This example illustrates how to use Hough Transform to find lines
  
  Usage:
      houghlines.py [<image_name>]
      image argument defaults to ../data/pic1.png
  '''
  
  # Python 2/3 compatibility
  from __future__ import print_function
  
  import cv2
  import numpy as np
  import sys
  import math
  
  if __name__ == '__main__':
      print(__doc__)
  
      try:
          fn = sys.argv[1]
      except IndexError:
          fn = "../data/pic1.png"
  
      src = cv2.imread(fn)
      dst = cv2.Canny(src, 50, 200)
      cdst = cv2.cvtColor(dst, cv2.COLOR_GRAY2BGR)
  
      if True: # HoughLinesP
          lines = cv2.HoughLinesP(dst, 1, math.pi/180.0, 40, np.array([]), 50, 10)
          a,b,c = lines.shape
          for i in range(a):
              cv2.line(cdst, (lines[i][0][0], lines[i][0][1]), (lines[i][0][2], lines[i][0][3]), (0, 0, 255), 3, cv2.LINE_AA)
  
      else:    # HoughLines
          lines = cv2.HoughLines(dst, 1, math.pi/180.0, 50, np.array([]), 0, 0)
          if lines != None:
              a,b,c = lines.shape
              for i in range(a):
                  rho = lines[i][0][0]
                  theta = lines[i][0][1]
                  a = math.cos(theta)
                  b = math.sin(theta)
                  x0, y0 = a*rho, b*rho
                  pt1 = ( int(x0+1000*(-b)), int(y0+1000*(a)) )
                  pt2 = ( int(x0-1000*(-b)), int(y0-1000*(a)) )
                  cv2.line(cdst, pt1, pt2, (0, 0, 255), 3, cv2.LINE_AA)
                  
              cv2.imshow("detected lines", cdst)
  
      cv2.imshow("source", src)
      cv2.waitKey(0)
  
new_contents: #!/usr/bin/python
  
  '''
  This example illustrates how to use Hough Transform to find lines
  
  Usage:
      houghlines.py [<image_name>]
      image argument defaults to ../data/pic1.png
  '''
  
  # Python 2/3 compatibility
  from __future__ import print_function
  
  import cv2
  import numpy as np
  import sys
  import math
  
  if __name__ == '__main__':
      print(__doc__)
  
      try:
          fn = sys.argv[1]
      except IndexError:
          fn = "../data/pic1.png"
  
      src = cv2.imread(fn)
      dst = cv2.Canny(src, 50, 200)
      cdst = cv2.cvtColor(dst, cv2.COLOR_GRAY2BGR)
  
      if True: # HoughLinesP
          lines = cv2.HoughLinesP(dst, 1, math.pi/180.0, 40, np.array([]), 50, 10)
          a,b,c = lines.shape
          for i in range(a):
              cv2.line(cdst, (lines[i][0][0], lines[i][0][1]), (lines[i][0][2], lines[i][0][3]), (0, 0, 255), 3, cv2.LINE_AA)
  
      else:    # HoughLines
          lines = cv2.HoughLines(dst, 1, math.pi/180.0, 50, np.array([]), 0, 0)
          if lines != None:
              a,b,c = lines.shape
              for i in range(a):
                  rho = lines[i][0][0]
                  theta = lines[i][0][1]
                  a = math.cos(theta)
                  b = math.sin(theta)
                  x0, y0 = a*rho, b*rho
                  pt1 = ( int(x0+1000*(-b)), int(y0+1000*(a)) )
                  pt2 = ( int(x0-1000*(-b)), int(y0-1000*(a)) )
                  cv2.line(cdst, pt1, pt2, (0, 0, 255), 3, cv2.LINE_AA)
  
              cv2.imshow("detected lines", cdst)
  
      cv2.imshow("source", src)
      cv2.waitKey(0)
  
subject: Update houghlines.py