15_2.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import cv2
import numpy as np
from matplotlib import pyplot as plt

img = cv2.imread(
    "F:/GitHub/children-python/Python_Books/OpenCV-Python-Tutoria/opencv01.jpg", 0)

ret, th1 = cv2.threshold(img, 127, 255, cv2.THRESH_BINARY)
# 11为Block size, 2为C值
th2 = cv2.adaptiveThreshold(img, 255, cv2.ADAPTIVE_THRESH_MEAN_C, cv2.THRESH_BINARY, 11, 2)
th3 = cv2.adaptiveThreshold(img, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY, 11, 2)
titles = ['Original Image',
          'Global Thresholding (v = 127)', 'Adaptive Mean Thresholding', 'Adaptive Gaussian Thresholding']
images = [img, th1, th2, th3]
for i in range(4):
    plt.subplot(2, 2, i+1), plt.imshow(images[i], 'gray')
    plt.title(titles[i])
    plt.xticks([]), plt.yticks([])
plt.show()

# 自适应阈值