import numpy as np
import cv2
import matplotlib.pyplot as plt
img = cv2.imread('./images/pill_002.png')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

ret,thresh = cv2.threshold(gray,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
plt.subplot(221),plt.imshow(thresh,cmap='gray'),plt.title('thresh')

# noise removal
kernel = np.ones((3,3),np.uint8)
opening = cv2.morphologyEx(thresh,cv2.MORPH_OPEN,kernel,iterations=2)
sure_bg = cv2.dilate(opening,kernel,iterations=1)
plt.subplot(222),plt.imshow(sure_bg,cmap='gray'),plt.title('sure_bg')


plt.show()