opencv实现小学试题识别，试题判断正误

# -*- coding:utf-8 -*-
# /usr/bin/python
'''
Author:Yan Errol  Email:2681506@gmail.com   Wechat:qq260187357
Date:2019-05-08--13:48
File：img2binary.py
Describe:读取图片，图片灰度化处理，灰度处理后的图片二值化
'''

print (__doc__)

import cv2 as cv
import numpy as np
from matplotlib import pyplot as plt


def read_img(path):
    # Load an color image in grayscale
    img = cv.imread(path)
    return img

def imgs2gray(img):
    im_gray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
    return im_gray

def imgs2binary(img):
    im_at_mean = cv.adaptiveThreshold(img,255, cv.ADAPTIVE_THRESH_GAUSSIAN_C, cv.THRESH_BINARY, 5,