#分水岭算法进行图像分割

import cv2
import numpy as np
from matplotlib import pyplot as plt

img = cv2.imread('../img/plants.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

#设置阈值
ret, thresh = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY_INV+cv2.THRESH_OTSU)

#去噪
kernel = np.ones((3, 3), np.uint8)
opening = cv2.morphologyEx(thresh, cv2.MORPH_OPEN, kernel, iterations=2)

sure_bg = cv2.dilate(opening, kernel, iterations=3)
dist_transform = cv2.distanceTransform(opening, cv2.DIST_L2, 5)
ret, sure_fg = cv2.threshold(dist_transform, 0.7*dist_transform.max(), 255, 0)

#去除背景和前景种重叠部分
sure_fg = np.uint8(sure_fg)
unknown = cv2.subtract(sure_bg, sure_fg)

#设定栅栏，阻止水汇聚
ret, markers = cv2.connectedComponents(sure_fg)

markers = markers+1
markers[unknown==255]=0

#开门
markers = cv2.watershed(img, markers)
img[markers==-1] = [255, 0, 0]
plt.imshow(img)
plt.show()