import numpy as np
import cv2

img=cv2.imread("opencv-logo.png")
imgray=cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
ret, thresh=cv2.threshold(imgray, 127,255,0)
contours, hierarchy=cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)
print("Number of contours : " + str(len(contours)))
print(contours[0])

cv2.drawContours(img, contours, -1, (0,255,0), 3)
#cv2.imshow("Bw", imgray)
cv2.imshow("Original", img)
#cv2.imshow("Thrsh", thresh)

cv2.waitKey()
cv2.destroyAllWindows()