在这篇文章中，我们将看到如何使用OpenCV扫描二维码。您将需要OpenCV3.4.4或4.0.0及更高版本来运行代码。

1 二维码(QRCode)扫描

在OpenCV中扫描二维码很简单。我们首先读取图像。然后，我们实例化QRCodeDetector对象并使用detectAndDecode方法来查找QR码的数据和位置。最后，我们进行结果显示。

QR Code scanner image

具体代码如下：

C++：

// QRCode_scanner.cpp

#include "pch.h"
#include <iostream>
#include <opencv2/opencv.hpp>
#include <iostream>

using namespace cv;
using namespace std;

/**
 * @brief 用于显示检测到的QR码周围的框
 * 
 * @param im 
 * @param bbox 
 */
void display(Mat &im, Mat &bbox)
{
	int n = bbox.rows;
	for (int i = 0; i < n; i++)
	{
		line(im, Point2i(bbox.at<float>(i, 0), bbox.at<float>(i, 1)),
			 Point2i(bbox.at<float>((i + 1) % n, 0), bbox.at<float>((i + 1) % n, 1)), Scalar(255, 0, 0), 3);
	}
	imshow("Result", im);
}

int main()
{
	// Read image
	Mat inputImage = imread("./image/demo.jpg");

	//QR检测器
	QRCodeDetector qrDecoder = QRCodeDetector::QRCodeDetector();

	//二维码边框坐标，提取出来的二维码
	Mat bbox, rectifiedImage;

	//检测二维码
	std::string data = qrDecoder.detectAndDecode(inputImage, bbox, rectifiedImage);

	//获取二维码中的数据链接
	if (data.length() > 0)
	{
		cout << "Decoded Data : " << data << endl;
		display(inputImage, bbox);
		rectifiedImage.convertTo(rectifiedImage, CV_8UC3);
		//展示二维码
		imshow("Rectified QRCode", rectifiedImage);

		waitKey(0);
	}
	else
	{
		cout << "QR Code not detected" << endl;
	}
	return 0;
}

Python:

import cv2
import numpy as np
import time


inputImage = cv2.imread("./image/demo.jpg")

# Display barcode and QR code location
def display(im, bbox):
    n = len(bbox)
    for j in range(n):
        cv2.line(im, tuple(bbox[j][0]), tuple(bbox[ (j+1) % n][0]), (255,0,0), 3)

    # Display results
    cv2.imshow("Results", im)

# Create a qrCodeDetector Object
qrDecoder = cv2.QRCodeDetector()

# Detect and decode the qrcode
t = time.time()
data,bbox,rectifiedImage = qrDecoder.detectAndDecode(inputImage)
print("Time Taken for Detect and Decode : {:.3f} seconds".format(time.time() - t))
if len(data)>0:
    print("Decoded Data : {}".format(data))
    display(inputImage, bbox)
    rectifiedImage = np.uint8(rectifiedImage);
    cv2.imshow("Rectified QRCode", rectifiedImage);
else:
    print("QR Code not detected")
    cv2.imshow("Results", inputImage)
cv2.imwrite("output.jpg",inputImage)
cv2.waitKey(0)
cv2.destroyAllWindows()