【Python】【OpenCV】定位二维码

 1 import cv2
 2 import numpy
 3 
 4 
 5 def qrcode(image):
 6     # 有些二维码和边缘紧贴，无法识别出整个矩形，所以我们先对图片大小进行扩展
 7     expand_length = 10
 8     edge = expand_length // 2
 9     h, w = image.shape[:2]
10     image_extend = numpy.zeros((image.shape[0] + expand_length, image.shape[1] + expand_length, 3), numpy.uint8)
11     image_extend[:] = 255
12     image_extend[edge:edge + h, edge:edge + w] = image
13 
14     # 转灰度、二值化、找轮廓
15     gray = cv2.cvtColor(image_extend, cv2.COLOR_BGR2GRAY)
16     # blur = cv2.GaussianBlur(gray, (5, 5), 0)
17     _, thresh = cv2.threshold(gray, 127, 255, cv2.THRESH_BINARY)
18     contours, hir = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
19 
20     '''
21     2.4282182798755647
22     2.3203121154092337
23     2.3487607213520345
24     2.318010267306266
25     '''
26 
27     # 三个“回”字特征轮廓存储
28     parent_hierarchy_list = []
29     parent_contours_list = []
30 
31     # 通过层级信息去查找三个“回”字特征区域
32     for index, item in enumerate(hir[0][:-2]):  # 查找最外层（A）轮廓
33         if item[2] != -1:
34             parent_index = item[2] - 1
35             if hir[0][index+1][3] == parent_index:  # 查找次一层（B）轮廓
36                 child_first = hir[0][index+1][2] - 1
37                 if hir[0][index+2][3] == child_first:   # 查找最里层（C）轮廓
38                     # 计算A轮廓的周长和C轮廓周长的比值
39                     error = cv2.arcLength(contours[parent_index], True) / cv2.arcLength(contours[parent_index + 2], True)
40                     if 2 < error < 3:
41                         parent_hierarchy_list.append(item)
42                         parent_contours_list.append(contours[index])
43                         # 绘制出三个“回”字特征区域的最外层轮廓
44                         cv2.drawContours(image_extend, contours, index, (0, 255, 0), 3)
45 
46     # 将整个二维码区域绘制出来
47     points_list = []
48     for index, box in enumerate(parent_contours_list):
49         x, y, w, h = cv2.boundingRect(box)
50         if index == 0:
51             points_list.append((x, y+h))
52         if index == 1:
53             points_list.append((x+w, y))
54         if index == 2:
55             points_list.append((x, y))
56     points_list = numpy.array(points_list)
57     rect = cv2.minAreaRect(points_list)
58     box = cv2.boxPoints(rect)
59     box = numpy.int0(box)
60     cv2.drawContours(image_extend, [box], 0, (255, 0, 0), 2)
61 
62     cv2.imshow('', image_extend)
63 
64 
65 if __name__ == '__main__':
66     img = cv2.imread('../images/QRCode_3.png')
67     qrcode(img)
68     cv2.waitKey()
69     cv2.destroyAllWindows()