otsu_Threshold.py

import numpy as np
import cv2
def otsu(gray):
    pixel_number = gray.shape[0] * gray.shape[1]
    mean_weigth = 1.0/pixel_number
    his, bins = np.histogram(gray, np.arange(0,257))
    final_thresh = -1
    final_value = -1
    intensity_arr = np.arange(256)
    for t in bins[1:-1]: # This goes from 1 to 254 uint8 range (Pretty sure wont be those values)
        pcb = np.sum(his[:t])
        pcf = np.sum(his[t:])
        Wb = pcb * mean_weigth
        Wf = pcf * mean_weigth

        mub = np.sum(intensity_arr[:t]*his[:t]) / float(pcb)
        muf = np.sum(intensity_arr[t:]*his[t:]) / float(pcf)
        #print mub, muf
        value = Wb * Wf * (mub - muf) ** 2

        if value > final_value:
            final_thresh = t
            final_value = value
    final_img = gray.copy()
    print(final_thresh)
    final_img[gray > final_thresh] = 255
    final_img[gray < final_thresh] = 0

    return final_img

image = cv2.imread("gray2.png")
a = otsu(gray= image)
cv2.imshow("attempt",a)
cv2.waitKey(0)