python-图像目标监测（1）识别答题卡

 # -*- coding: utf-8 -*-
 """
 Created on Thu Dec 20 16:05:10 2018

 @author: leizhen.liu
 """

 import cv2.cv2 as cv2
 import numpy as np

 data = cv2.imread('anwser.jpg')
 cv2.imshow('anwser',data)

 #灰度處理
 gray = cv2.cvtColor(data,cv2.COLOR_BGR2GRAY)
 cv2.imshow('gray',gray)

 kernel = np.ones((5,5),np.uint8) 

 #膨脹操作
 pengzhang = cv2.dilate(gray,kernel,iterations =1)
 cv2.imshow('pengzhang',pengzhang)

 #腐蝕
 fushi = cv2.erode(pengzhang,kernel,iterations =1)
 cv2.imshow('fushi',fushi)

 #二值化
 ret ,color2 = cv2.threshold(fushi,127,255,cv2.THRESH_BINARY_INV)
 cv2.imshow('binary',color2)

 #轮廓
 _,contours,hierarchy=cv2.findContours(color2,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
 #newimg=np.zeros_like(color2)
 cv2.drawContours(data, contours, -1, (0,0,255),1)
 cv2.imshow('lunkuo',data)

 cv2.waitKey(0)

注意点：1、cv2.waitKey() 要写否则图片不能显示。