python opencv 二值化 计算白色像素点的实例

#! /usr/bin/env python
# -*- coding: utf-8 -*-
import cv2
import numpy as np
from PIL import Image

area = 0
def ostu(img):
  global area
  image=cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # 转灰度
  blur = cv2.GaussianBlur(image,(5,5),0) # 阈值一定要设为 0 ！高斯模糊
  ret3,th4 = cv2.threshold(blur,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU) # 二值化 0 = black ; 1 = white
  # cv2.imshow('image', th4)
  # a = cv2.waitKey(0)
  # print a
  height, width = th4.shape
  for i in range(height):
    for j in range(width):
      if th4[i, j] == 255:
        area += 1
  return area