OpenCV : undefined reference to imread()

Question

I have configured OpenCV 3.1.0 in Eclipse Mars. These are my configuration,

G++ includes: D:/opencv/build/install/include; GCC includes: D:/opencv/build/install/include

Linker libraries: libopencv_core310, libopencv_highgui310

Linker libraries path: D:/opencv/build/lib (files in this directory are like libopencv_core310.dll.a)

I am getting an error like this,

imageRead.cpp:15: undefined reference to `cv::imread(cv::String const&, int)'

This is my imageRead.cpp file,

#include <iostream>
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"

using namespace std;
using namespace cv;

int main(int argc, const char** argv) {
    Mat img = imread("D:/sample.jpg", CV_LOAD_IMAGE_UNCHANGED);
    if (img.empty()) {
        cout << "Error: Image cannot be loaded." << endl;
        system("pause");
        return -1;
    }
    namedWindow("Image Window", CV_WINDOW_AUTOSIZE);
    imshow("Image Window", img);
    if (waitKey() == 27) {
        return -1;
    }
    destroyWindow("Image Window");
    return 0;
}

Can anyone help with this error ?

Parsley

It says "Error starting process: Cannot run program" – Parsley

that's unrelated to your original question. – Urbanna

Try by adding opencv_highgui in linker libray. – Inebriety

Answer 1

Since OpenCV3, the imread function resides in the imgcodecs module. Imread should work once you add the opencv_imgcodecs library to your project (note: imgcodecs, not imcodecs).

Protanopia

The actual code is #include <opencv2/imgcodecs.hpp> – Septic

Answer 2

I recommend to link the following libraries:

opencv_core
opencv_highgui
opencv_imgproc
opencv_imgcodecs

And in the .cpp file, you can include like this

    #include <iostream>
    #include <opencv2/core/core.hpp>
    #include <opencv2/highgui/highgui.hpp>
    #include <opencv2/imgproc/imgproc.hpp>

    using namespace std;
    using namespace cv;

Or

    #include <iostream>
    #include <opencv2/opencv.hpp>

    using namespace std;
    using namespace cv;

Spilt

Answer 3

This function is located in opencv_imgcodecs library. It also worths mentioning that you may need to put your object file before libraries in order to link successfully:

g++ -c -I/usr/include/opencv4/opencv -I/usr/include/opencv4 main.cpp
g++ main.o -lopencv_imgcodecs $(OTHER_FLAGS) -o main

Phanotron