请写出python opencv 画出二值化图片百分之一的轮廓点具体代码

import cv2
import numpy as np

img = cv2.imread('image.jpg', cv2.IMREAD_GRAYSCALE)
ret, thresh = cv2.threshold(img, 127, 255, 0)
contours, hierarchy = cv2.findContours(thresh, 1, 2)

for cnt in contours:
epsilon = 0.001 * cv2.arcLength(cnt, True)
approx = cv2.approxPolyDP(cnt, epsilon, True)
cv2.drawContours(img, [approx], 0, (0, 255, 0), 5)

cv2.imshow('image', img)
cv2.waitKey(0)
cv2.destroyAllWindows()