How to link opencv in QtCreator and use Qt library

The originally accepted answer did not work for me, I am running MSVC2013 Professional and QT5.9. I found SIMPLE and SUREFIRE CROSS-PLATFORM solution that should help anyone who is trying to link an external library (like openCV) with QT.

The steps listed below are found in the Qt5 documentation: http://doc.qt.io/qtcreator/creator-project-qmake-libraries.html under the "To Add Library" section.

  1. Right click on the project file located in the 'project pane' on the left side of the creator... and select "Add Library..."
  2. Follow the instructions of the wizard

Let me add some specificity from here:

  1. Select "External Library"
  2. For the "Library File" navigate to your opencv_worldXXX.lib file (or opencv_worldXXXd.lib file, you will notice that by specifying only one or the other the wizard has a checkbox which includes the other automatically) [ex. ...\opencv\build\x64\vc12\lib\opncv_world310.lib]
  3. For the "Include Folder" navigate to the "include" folder within the build. [ex. ...\opencv\build\include]
  4. Select your operating system, dynamic/static library (whichever is appropriate)
  5. Hit NEXT, CLEAN UP, and RUN!

Finally I am starting to be happy. When adjusting this question I had to try all the ways how to define LIBS. Listing them manually helped, at first I wrote them somehow wrong.

This is how it works finally:

LIBS += -LC:\\Programs\\opencv24\\opencv_bin2\\bin \
    libopencv_core240d \
    libopencv_highgui240d \
    libopencv_imgproc240d \
    libopencv_features2d240d \
    libopencv_calib3d240d \