Python OCR提取普通数字图形验证中的数字

截取图形验证码：

 # -*- coding: UTF-8 -*-
 '''
 Created on 2016年7月4日

 @author: xuxianglin
 '''
 import os
 import tempfile
 import shutil

 from PIL import Image

 PATH = lambda p: os.path.abspath(p)
 TEMP_FILE = PATH(tempfile.gettempdir() + "/temp_screen.png")

 class Appium_Extend(object):
     def __init__(self, driver):
         self.driver = driver

     def get_screenshot_by_element(self, element):
         #先截取整个屏幕，存储至系统临时目录下
         self.driver.get_screenshot_as_file(TEMP_FILE)

         #获取元素bounds
         location = element.location
         size = element.size
         box = (location["x"], location["y"], location["x"] + size["width"], location["y"] + size["height"])

         #截取图片
         image = Image.open(TEMP_FILE)
         newImage = image.crop(box)
         newImage.save(TEMP_FILE)

         return self

     def get_screenshot_by_custom_size(self, start_x, start_y, end_x, end_y):
         #自定义截取范围
         self.driver.get_screenshot_as_file(TEMP_FILE)
         box = (start_x, start_y, end_x, end_y)

         image = Image.open(TEMP_FILE)
         newImage = image.crop(box)
         newImage.save(TEMP_FILE)

         return self

     def write_to_file( self, dirPath, imageName, form = "png"):
         #将截屏文件复制到指定目录下
         if not os.path.isdir(dirPath):
             os.makedirs(dirPath)
         shutil.copyfile(TEMP_FILE, PATH(dirPath + "/" + imageName + "." + form))

     def load_image(self, image_path):
         #加载目标图片供对比用
         if os.path.isfile(image_path):
             load = Image.open(image_path)
             return load
         else:
             raise Exception("%s is not exist" %image_path)

     def same_as(self, load_image, percent):
         #对比图片，percent值设为0，则100%相似时返回True，设置的值越大，相差越大
         import math
         import operator

         image1 = Image.open(TEMP_FILE)
         image2 = load_image

         histogram1 = image1.histogram()
         histogram2 = image2.histogram()

         differ = math.sqrt(reduce(operator.add, list(map(lambda a,b: (a-b)**2, \
                                                          histogram1, histogram2)))/len(histogram1))
         if differ <= percent:
             return True
         else:
             return False

在定位元素中调用改方法：

   vcode=self.driver.find_element_by_id("com.ajb.sp:id/changepsw_code_img")
   self.extend.get_screenshot_by_element(vcode).write_to_file("..\\resource\\vcode\\","image")
   self.assertTrue(os.path.isfile('..\\resource\\vcode\\image.png'))
   image=Image.open('..\\resource\\vcode\\image.png')
   vcode_number=pytesseract.image_to_string(image)
   print u"截取到的验证码为：%s"%vcode_number