points = cv2.goodFeaturesToTrack(gray, 100, 0.01, 10)
points = np.int0(points).reshape(-1,2)

for point in points:
  x, y = point.ravel()
  cv2.circle(img, (x, y), 10, (0, 255, 0), -1)

cv2.line(img, (0, y1), (1000, y1), (0, 255, 0), thickness=3, lineType=8)
cv2.line(img, (0, y2), (1000, y2), (0, 255, 0), thickness=3, lineType=8)

""" 
@author: qq群686070107
""" 
import cv2
import numpy as np
img=cv2.imread("1.jpg")
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
points = cv2.goodFeaturesToTrack(gray, 100, 0.01, 10)
points = np.int0(points).reshape(-1,2)

for point in points:
  x, y = point.ravel()
  cv2.circle(img, (x, y), 10, (0, 255, 0), -1)


y1 = min(points[:,1])
y2 = max(points[:,1])

## small and big enough 
cv2.line(img, (0, y1), (1000, y1), (0, 255, 0), thickness=3, lineType=8)
cv2.line(img, (0, y2), (1000, y2), (0, 255, 0), thickness=3, lineType=8)

cv2.imshow("img", img)
cv2.waitKey(0)