如何在 Linux 上使用 C++ opencv 库解码 QRCODE？

Question

I am working with opencv c++ library to decode Qrcode.Here I given sample test code which is from this website: https://www.learnopencv.com/opencv-qr-code-scanner-c-and-python/

When I am compiling this test program I am getting following error:

test.cc: In function ‘int main(int, char**)’:
test.cc:29:3: error: ‘QRCodeDetector’ was not declared in this scope
   QRCodeDetector qrDecoder = QRCodeDetector::QRCodeDetector();
   ^~~~~~~~~~~~~~
test.cc:33:22: error: ‘qrDecoder’ was not declared in this scope
   std::string data = qrDecoder.detectAndDecode(inputImage, bbox, rectifiedImage)

How to resolve this error?

test.cc:
//https://www.learnopencv.com/opencv-qr-code-scanner-c-and-python/
#include <opencv2/objdetect.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>

using namespace cv;
using namespace std;

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(int argc, char* argv[])
{
  // Read image
  Mat inputImage;

  inputImage = imread(argv[1]);

  QRCodeDetector qrDecoder = QRCodeDetector::QRCodeDetector();

  Mat bbox, rectifiedImage;

  std::string data = qrDecoder.detectAndDecode(inputImage, bbox, rectifiedImage);
  if(data.length()>0)
  {
    cout << "Decoded Data : " << data << endl;

    display(inputImage, bbox);
    rectifiedImage.convertTo(rectifiedImage, CV_8UC3);
    imshow("Rectified QRCode", rectifiedImage);

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

//compile
g++ test.cc -o test `pkg-config opencv --cflags --libs`

Answer 1

First of all, code is compatible with OpenCV 4.0, so be sure that you are using OpenCV 4.0. If you are using OpenCV 4.0, you may have refered different version of OpenCV path in eclipse.

For solution, there is two steps.

Step1

From Terminal, type pkg-config --cflags opencv4 . Output will be like I/usr/local/include/opencv4/opencv . Copy output and paste it place which is shown in first link.

https://drive.google.com/open?id=1WSBEOaSF6JJvOiUSI_kop8wnRaK8TOIt

Steps2

Again from terminal, type pkg-config --libs opencv4 . Output will be like L/usr/local/lib . Copy output and paste it place which is shown in second link. Than add headers referances to Libraries(-l) section like shown in link.

https://drive.google.com/open?id=1VYJHNV10P8oj_pwaUh3GZJwWu8vDmUxA

This steps will be solution your problem.

Answer 2

Referring thread below(same problem but has all details): https://forum.opencv.org/t/quirc-error-in-opencv-4/6804/3 On a Ubuntu 22.04.1

On linux OpenCV4.* build detect presence of 3rd party libs, to make it use bundled QUIRC use for cmake: -DBUILD_QUIRC=ON -DQUIRC=ON

Full cmd be like:

cmake       -D CMAKE_BUILD_TYPE=RELEASE \
            -D CMAKE_INSTALL_PREFIX=/usr/local/OpenCV47 \
            -D INSTALL_C_EXAMPLES=ON \
            -D WITH_TBB=ON \
            -D WITH_V4L=ON \
            -D WITH_OPENGL=ON \
            -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules \
            -D BUILD_EXAMPLES=ON \
            -DBUILD_QUIRC=ON -DQUIRC=ON \
             ..

Above cmd worked for me, other options can be adjusted to suit your needs. --batcilla enter code here