How to link properly Dcmtk with Qt for Linux?

My goal is open Dicom files and convert thes into cv::Mat to process them with Opencv.

I have compiled dcmtk 3.6.3 on ubuntu 18.4.1 and tried to link it with Qt 5.11.1 with Qt Creator 4.6.2 but failed to do so.

# pro file
QT       += core
QT       -= gui

TARGET = DcmtkTesting
CONFIG   += console
CONFIG   -= app_bundle

TEMPLATE = app


DCMTK_PREFIX = "/home/ismail/dcmtk363"
DCMTK_LIBS_PREFIX=$$DCMTK_PREFIX"/lib"
DCMTK_INCLUDE=$$DCMTK_PREFIX"/include"
INCLUDEPATH+=$$DCMTK_INCLUDE

LIBS += -L$$DCMTK_LIBS_PREFIX

SOURCES += main.cpp

and for the main: #include

#include "dcmtk/config/osconfig.h"
#include "dcmtk/dcmdata/dctk.h"
#include <dcmtk/dcmimgle/dcmimage.h>

#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    DicomImage *image = new DicomImage("test.dcm");
    if (image != NULL)
    {
      if (image->getStatus() == EIS_Normal)
      {
        if (image->isMonochrome())
        {
          image->setMinMaxWindow();
          Uint8 *pixelData = (Uint8 *)(image->getOutputData(8 /* bits*/));
          if (pixelData != NULL)
          {
            /* do something useful with the pixel data */
          }
        }
      } else
        cout << "Error: cannot load DICOM image (" <<   DicomImage::getString(image->getStatus()) << ")" << endl;
    }
    delete image;

    return a.exec();
}

and I got this errors:

Answer

The error indicates that the linker could not find the symbols (methods) provided by the library. In your .pro file, you pointed the linker to a directory where your library is located, but you forgot to specify which library should be linked.

So you have to modify the line LIBS +=... accordingly, e.g.:

LIBS += -L$$DCMTK_LIBS_PREFIX -ldcmtk

Since I don’t know the actual name of the library, I use dcmtk in my example. You may have to adopt it to fit your build environment. Just make sure that you have the -l (lower case L), immediately followed by the library name.