答题卡识别

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分别进行预处理，轮廓检测、轮廓排序，透视变换、寻找圆圈轮廓、输出每个轮廓，对比答案

import cv2
import numpy as np
def cv_show(name,img):
    cv2.imshow(name,img)
    cv2.waitKey(0)
    cv2.destroyAllWindows()
def order_points(pts):
    rect = np.zeros((4,2),dtype = "float32")#初始化同样大小的图像变量
    s = pts.sum(axis=1)#根据y坐标，提取参数
    rect[0] = pts[np.argmin(s)]
    rect[2] = pts[np.argmax(s)]
    d = np.diff(pts,axis=1)
    rect[1] = pts[np.argmin(d)]
    rect[3] = pts[np.argmax(d)]
    return rect
def four_point_transform(img,pts):
    rect = order_points(pts)
    (tl,tr,br,bl) = rect
    widthA = np.sqrt((br[0]-bl[0])**2+(br[1]-bl[1])**2)
    w