Otsu.py

import numpy as np
import cv2
from matplotlib import pyplot as plt
img = cv2.imread("imgs/chapter5/text2.png", 0); 
#img = cv2.blur(img, (3, 3));


# global thresholding
ret1,th1 = cv2.threshold(img,127,255,cv2.THRESH_BINARY)

# Otsu's thresholding
ret2,th2 = cv2.threshold(img,127,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)

# Otsu's thresholding after Gaussian filtering
blur = cv2.GaussianBlur(img,(3,3),0)
ret3,th3 = cv2.threshold(blur,127,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)



f = plt.figure(figsize=(15,15))
f.add_subplot(2, 2, 1).set_title('Original Image');
plt.imshow(img, cmap = "gray")
f.add_subplot(2, 2, 2).set_title('Simple Threshold');
plt.imshow(th1, cmap = "gray");
f.add_subplot(2, 2, 3).set_title("Otsu's thresholding");
plt.imshow(th2, cmap = "gray");
f.add_subplot(2, 2, 4).set_title("Otsu's thresholding after Gaussian filtering");
plt.imshow(th3, cmap = "gray");
plt.show();