Python+OpenCV实现定位二维码

import cv2
import numpy


def qrcode(image):
    # 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
    expand_length = 10
    edge = expand_length // 2
    h, w = image.shape[:2]
    image_extend = numpy.zeros((image.shape[0] + expand_length, image.shape[1] + expand_length, 3), numpy.uint8)
    image_extend[:] = 255
    image_extend[edge:edge + h, edge:edge + w] = image

    # 转灰度、二值化、找轮廓
    gray = cv2.cvtColor(image_extend, cv2.COLOR_BGR2GRAY)
    # blur = cv2.GaussianBlur(gray, (5, 5), 0)
    _, thresh = cv2.threshold(gray, 127, 255, cv2.THRESH_BINARY)
    contours, hir = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

    '''
    2.4282182798755647
    2.3203121154092337
    2.3487607213520345
    2.318010267306266
    '''

    # 三个“回”字特征轮廓存储
    parent_hierarchy_list = []
    parent_contours_list = []

    # 通过层级信息去查找三个“回”字特征区域
    for index, item in enumerate(hir[0][:-2]):  # 查找最外层（A）轮廓
        if item[2] != -1:
            parent_index = item[2] - 1
            if hir[0][index+1][3] == parent_index:  # 查找次一层（B）轮廓
                child_first = hir[0][index+1][2] - 1
                if hir[0][index+2][3] == child_first:   # 查找最里层（C）轮廓
                    # 计算A轮廓的周长和C轮廓周长的比值
                    error = cv2.arcLength(contours[parent_index], True) / cv2.arcLength(contours[parent_index + 2], True)
                    if 2 < error < 3:
                        parent_hierarchy_list.append(item)
                        parent_contours_list.append(contours[index])
                        # 绘制出三个“回”字特征区域的最外层轮廓
                        cv2.drawContours(image_extend, contours, index, (0, 255, 0), 3)

    # 将整个二维码区域绘制出来
    points_list = []
    for index, box in enumerate(parent_contours_list):
        x, y, w, h = cv2.boundingRect(box)
        if index == 0:
            points_list.append((x, y+h))
        if index == 1:
            points_list.append((x+w, y))
        if index == 2:
            points_list.append((x, y))
    points_list = numpy.array(points_list)
    rect = cv2.minAreaRect(points_list)
    box = cv2.boxPoints(rect)
    box = numpy.int0(box)
    cv2.drawContours(image_extend, [box], 0, (255, 0, 0), 2)

    cv2.imshow('', image_extend)


if __name__ == '__main__':
    img = cv2.imread('../images/QRCode_3.png')
    qrcode(img)
    cv2.waitKey()
    cv2.destroyAllWindows()