import cv2
import numpy as np
import matplotlib.pylab as plt
## Simple Otsu over hue
six = cv2.imread('7zovC.jpg')
##convert to hsv
hsv = cv2.cvtColor(six, cv2.COLOR_BGR2HSV)
hue = hsv[:, :, 0]
binary_img = cv2.threshold(hue, 128, 255, cv2.THRESH_OTSU)
plt.figure()
plt.imshow(binary_img*255)
plt.show()