import cv2


def otsu_seg(img):

  ret_th, bin_img = cv2.threshold(img, 0, 255, cv2.THRESH_BINARY+cv2.THRESH_OTSU)

  return ret_th, bin_img

def find_pole(bin_img):
  img, contours, hierarchy = cv2.findContours(bin_img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
  area = 0
  for i in range(len(contours)):
    area += cv2.contourArea(contours[i])
  area_mean = area / len(contours)
  mark = []
  for i in range(len(contours)):
    if cv2.contourArea(contours[i]) < area_mean:
      mark.append(i)

  return img, contours, hierarchy, mark

def draw_box(img,contours):
  img = cv2.rectangle(img,
         (contours[0][0], contours[0][1]),
         (contours[1][0], contours[1][1]),
         (255,255,255),
         3)
  return img

def main(img):
  ret, th = otsu_seg(img)
  img_new, contours, hierarchy, mark = find_pole(th)
  for i in range(len(contours)):
    if i not in mark:
      left_point = contours[i].min(axis=1).min(axis=0)
      right_point = contours[i].max(axis=1).max(axis=0)
      img = draw_box(img, (left_point, right_point))
  return img


if __name__ =="__main__":
  img = cv2.imread('G:/test.png')
  img = main(img)
  cv2.imwrite('G:/test_d.png', img)