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Using opencv3.1 with Qt5.5 in Windows 10

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  • SGaistS Offline
    SGaistS Offline
    SGaist
    Lifetime Qt Champion
    wrote on last edited by
    #4

    What exact problem do you have currently ?

    Interested in AI ? www.idiap.ch
    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

    1 Reply Last reply
    0
    • brotifyB Offline
      brotifyB Offline
      brotify
      wrote on last edited by brotify
      #5

      Ok let me say what I did so far;

      1. First I extracted opencv3.1 to directory C:\opencv2. Therefore initially there was two folders in this directory namely "source" and "build". Then I created a new folder named "release".
      2. To build libraries I used C make 3.4.3. I selected "C:/opencv2/sources" as a source directory and selected "C:/opencv2/release" to build binaries.
      3. I clicked "Configure" and selected "MinGW Makefiles" as generetor and selected "Specify native compilers". Then I selected "C:/Qt/Tools/mingw491_32/bin/gcc.exe" as the C compiler and "C:/Qt/Tools/mingw491_32/bin/g++.exe" as the C++ compiler. (By the way I am using Qt 5.4)
      4. I did not change any other options and clicked configure till all red lines disappear. Next I clicked "generate" and closed Cmake gui.

      5)Then I opened CMD window I opened the directory C:\opencv2\release and I typed "mingw32-make", it took about 30 minutes. Then I typed "mingw32-make install" .

      System variables that I added is shown in the picture.
      http://i.hizliresim.com/v5LnJr.png

      6)Then I created Qt console application and I added these to .pro file

      INCLUDEPATH += C:\opencv2\release\install\include
      LIBS += -LC:\\opencv2\\release\\install\\x86\\mingw\\bin\
          libopencv_core310 \
          libopencv_highgui310 \
          libopencv_imgproc310 \
          libopencv_features2d310 \
          libopencv_calib3d310 \
      Then I clicked "run qmake"
      

      In the source file

      #include <QCoreApplication>
      #include <opencv2/opencv.hpp>
      int main(int argc, char *argv[])
      {
          QCoreApplication a(argc, argv);
       
      
          return a.exec();
      }
      

      But I get the error,
      error: LNK1104: cannot open file 'libopencv_core310.obj'

      jsulmJ 1 Reply Last reply
      0
      • mrdebugM Offline
        mrdebugM Offline
        mrdebug
        wrote on last edited by
        #6

        Hi. You have to build OpenCV with MinGW only if you want to use Qt on Windows builded with MinGW.
        The OpenCV package already has the vs libraries.
        Anyway which are your cmake switches?

        Need programmers to hire?
        www.labcsp.com
        www.denisgottardello.it
        GMT+1
        Skype: mrdebug

        brotifyB 1 Reply Last reply
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        • brotifyB brotify

          Ok let me say what I did so far;

          1. First I extracted opencv3.1 to directory C:\opencv2. Therefore initially there was two folders in this directory namely "source" and "build". Then I created a new folder named "release".
          2. To build libraries I used C make 3.4.3. I selected "C:/opencv2/sources" as a source directory and selected "C:/opencv2/release" to build binaries.
          3. I clicked "Configure" and selected "MinGW Makefiles" as generetor and selected "Specify native compilers". Then I selected "C:/Qt/Tools/mingw491_32/bin/gcc.exe" as the C compiler and "C:/Qt/Tools/mingw491_32/bin/g++.exe" as the C++ compiler. (By the way I am using Qt 5.4)
          4. I did not change any other options and clicked configure till all red lines disappear. Next I clicked "generate" and closed Cmake gui.

          5)Then I opened CMD window I opened the directory C:\opencv2\release and I typed "mingw32-make", it took about 30 minutes. Then I typed "mingw32-make install" .

          System variables that I added is shown in the picture.
          http://i.hizliresim.com/v5LnJr.png

          6)Then I created Qt console application and I added these to .pro file

          INCLUDEPATH += C:\opencv2\release\install\include
          LIBS += -LC:\\opencv2\\release\\install\\x86\\mingw\\bin\
              libopencv_core310 \
              libopencv_highgui310 \
              libopencv_imgproc310 \
              libopencv_features2d310 \
              libopencv_calib3d310 \
          Then I clicked "run qmake"
          

          In the source file

          #include <QCoreApplication>
          #include <opencv2/opencv.hpp>
          int main(int argc, char *argv[])
          {
              QCoreApplication a(argc, argv);
           
          
              return a.exec();
          }
          

          But I get the error,
          error: LNK1104: cannot open file 'libopencv_core310.obj'

          jsulmJ Offline
          jsulmJ Offline
          jsulm
          Lifetime Qt Champion
          wrote on last edited by
          #7

          @brotify This should be changed:

          LIBS += -LC:\\opencv2\\release\\install\\x86\\mingw\\bin\
              libopencv_core310 \
              libopencv_highgui310 \
              libopencv_imgproc310 \
              libopencv_features2d310 \
              libopencv_calib3d310 \
          

          to:

          LIBS += -LC:/opencv2/release/install/x86/mingw/bin\
              -lopencv_core310 \
              -lopencv_highgui310 \
              -lopencv_imgproc310 \
              -lopencv_features2d310 \
              -lopencv_calib3d310 \
          

          In pro files you should use forward slashes in paths and not back slashes (even on Windows).
          Are the libraries directly in C:\opencv2\release\install\x86\mingw\bin?

          https://forum.qt.io/topic/113070/qt-code-of-conduct

          brotifyB 1 Reply Last reply
          0
          • jsulmJ jsulm

            @brotify This should be changed:

            LIBS += -LC:\\opencv2\\release\\install\\x86\\mingw\\bin\
                libopencv_core310 \
                libopencv_highgui310 \
                libopencv_imgproc310 \
                libopencv_features2d310 \
                libopencv_calib3d310 \
            

            to:

            LIBS += -LC:/opencv2/release/install/x86/mingw/bin\
                -lopencv_core310 \
                -lopencv_highgui310 \
                -lopencv_imgproc310 \
                -lopencv_features2d310 \
                -lopencv_calib3d310 \
            

            In pro files you should use forward slashes in paths and not back slashes (even on Windows).
            Are the libraries directly in C:\opencv2\release\install\x86\mingw\bin?

            brotifyB Offline
            brotifyB Offline
            brotify
            wrote on last edited by
            #8

            @jsulm

            INCLUDEPATH += C:\opencv2\release\install\include
            LIBS += -LC:/opencv2/release/install/x86/mingw/bin\
                -lopencv_core310 \
                -lopencv_highgui310 \
                -lopencv_imgproc310 \
                -lopencv_features2d310 \
                -lopencv_calib3d310 \
            
            INCLUDEPATH += C:/opencv2/release/install/include
            LIBS += -LC:/opencv2/release/install/x86/mingw/bin\
                -lopencv_core310 \
                -lopencv_highgui310 \
                -lopencv_imgproc310 \
                -lopencv_features2d310 \
                -lopencv_calib3d310 \
            

            I tried both of them but this time I get this error:
            LNK1104: cannot open file 'opencv_core310.lib'

            Let me show the screenshot of what is inside "C:\opencv2\release\install\x86\mingw\bin"
            http://i.hizliresim.com/0nkDAY.png

            jsulmJ 1 Reply Last reply
            0
            • mrdebugM mrdebug

              Hi. You have to build OpenCV with MinGW only if you want to use Qt on Windows builded with MinGW.
              The OpenCV package already has the vs libraries.
              Anyway which are your cmake switches?

              brotifyB Offline
              brotifyB Offline
              brotify
              wrote on last edited by brotify
              #9

              @mrdebug
              I have to say that I am not experienced developer. Therefore I did not fully understand what are saying. I used Mingw because in the tutorials thay were using Cmake and Mingw. If there are another method to use opencv in Qt project, it will be good to me to know.

              1 Reply Last reply
              0
              • mrdebugM Offline
                mrdebugM Offline
                mrdebug
                wrote on last edited by
                #10

                Sorry but all the tutorials that I have tried in order to to use OpenCV in all platforms are not perfectly usable. To setup OpenCV with Qt is more difficult than to write a OpenCV program.
                To start: what qt version are you using? The Qt version based on mingw32 or the version based on vc?

                Need programmers to hire?
                www.labcsp.com
                www.denisgottardello.it
                GMT+1
                Skype: mrdebug

                brotifyB 1 Reply Last reply
                0
                • brotifyB brotify

                  @jsulm

                  INCLUDEPATH += C:\opencv2\release\install\include
                  LIBS += -LC:/opencv2/release/install/x86/mingw/bin\
                      -lopencv_core310 \
                      -lopencv_highgui310 \
                      -lopencv_imgproc310 \
                      -lopencv_features2d310 \
                      -lopencv_calib3d310 \
                  
                  INCLUDEPATH += C:/opencv2/release/install/include
                  LIBS += -LC:/opencv2/release/install/x86/mingw/bin\
                      -lopencv_core310 \
                      -lopencv_highgui310 \
                      -lopencv_imgproc310 \
                      -lopencv_features2d310 \
                      -lopencv_calib3d310 \
                  

                  I tried both of them but this time I get this error:
                  LNK1104: cannot open file 'opencv_core310.lib'

                  Let me show the screenshot of what is inside "C:\opencv2\release\install\x86\mingw\bin"
                  http://i.hizliresim.com/0nkDAY.png

                  jsulmJ Offline
                  jsulmJ Offline
                  jsulm
                  Lifetime Qt Champion
                  wrote on last edited by
                  #11

                  @brotify Can you search for opencv_core310.lib (and other needed *.lib files) in the installation directory?

                  https://forum.qt.io/topic/113070/qt-code-of-conduct

                  1 Reply Last reply
                  0
                  • A Offline
                    A Offline
                    asanka424
                    wrote on last edited by
                    #12

                    It seems like you are trying to use OpenCV built using MinGW with Qt built with Visual Studio. There are two things you can do.

                    1. use OpenCV pre built. Which is in your build folder of OpenCV downloaded zip

                    2. change the kit in your Qt Creator to use MinGW build of Qt.

                    Hope this helps

                    brotifyB 1 Reply Last reply
                    0
                    • A asanka424

                      It seems like you are trying to use OpenCV built using MinGW with Qt built with Visual Studio. There are two things you can do.

                      1. use OpenCV pre built. Which is in your build folder of OpenCV downloaded zip

                      2. change the kit in your Qt Creator to use MinGW build of Qt.

                      Hope this helps

                      brotifyB Offline
                      brotifyB Offline
                      brotify
                      wrote on last edited by brotify
                      #13

                      Please note that I have solved my problem but I will not delete this post because it may help other people.
                      @asanka424
                      Thanks, I selected Mingw32 as the kit and it worked but this time I get a different error. I tried a simple opencv program which shows the image however it gives this error:
                      undefined reference to `cv::imread(cv::String const&, int)'

                      Here is my code,

                      #include <opencv2/core/core.hpp>
                      #include <opencv2/highgui/highgui.hpp>
                      #include <iostream>
                      
                      using namespace cv;
                      using namespace std;
                      
                      int main(  )
                      {
                      
                      
                          Mat image;
                          image = imread("img.jpg", CV_LOAD_IMAGE_COLOR);   
                      
                          if(! image.data )                       
                          {
                              cout <<  "Could not open or find the image" << std::endl ;
                              return -1;
                          }
                      
                          namedWindow( "Display window", WINDOW_AUTOSIZE );// Create a window for display.
                          imshow( "Display window", image );             
                      
                          waitKey(0);                                      
                          return 0;
                      }
                      
                      

                      and here is my .pro file

                      QT += core
                      QT -= gui
                      
                      CONFIG += c++11
                      
                      TARGET = untitled
                      CONFIG += console
                      CONFIG -= app_bundle
                      
                      INCLUDEPATH += C:/opencv2/release/install/include
                      LIBS += -LC:/opencv2/release/install/x86/mingw/bin\
                          -lopencv_core310 \
                          -lopencv_highgui310 \
                          -lopencv_imgproc310 \
                          -lopencv_features2d310 \
                          -lopencv_calib3d310 \
                      
                      
                      TEMPLATE = app
                      
                      SOURCES += main.cpp
                      

                      And lastly can you show me how to use first method that is using opencv pre-built?

                      1 Reply Last reply
                      0
                      • mrdebugM mrdebug

                        Sorry but all the tutorials that I have tried in order to to use OpenCV in all platforms are not perfectly usable. To setup OpenCV with Qt is more difficult than to write a OpenCV program.
                        To start: what qt version are you using? The Qt version based on mingw32 or the version based on vc?

                        brotifyB Offline
                        brotifyB Offline
                        brotify
                        wrote on last edited by brotify
                        #14

                        @mrdebug
                        I was not aware of that Qt has two different versions. So far I was using VC. Now I am using MinGw and it seems that the problem was this. Yet I have another problem which I posted before this post.

                        1 Reply Last reply
                        0
                        • brotifyB Offline
                          brotifyB Offline
                          brotify
                          wrote on last edited by brotify
                          #15

                          Ok, I want to thanks all of you who tried to help me. Hopefully I solved my problem. I solved the last problem by adding to .pro file

                          LIBS += "C:\opencv2\release\lib\libopencv_imgcodecs310.dll.a"
                          
                          1 Reply Last reply
                          0
                          • B Offline
                            B Offline
                            beginMyCoding
                            wrote on last edited by
                            #16

                            Hello
                            I am also in a same situation, i did not find any solution till now.
                            I am using Qt creator 5.5 with mingw492_32 and openCv 3.10 with VC.
                            When i try to write a small code to read the image matrix using cv::imread() it gives me error.

                            error: undefined reference to `cv::imread(cv::String const&, int)
                            

                            this is my

                            test.pro

                            QT       += core gui
                            
                            greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
                            
                            TARGET = Test
                            TEMPLATE = app
                            
                            
                            SOURCES += main.cpp\
                                    mainwindow.cpp
                            
                            HEADERS  += mainwindow.h
                            
                            FORMS    += mainwindow.ui
                            
                            INCLUDEPATH += LC:\opencv\build\include
                            
                                    LIBS += C:\opencv\build\x64\vc14\lib\opencv_world310.lib \
                                            C:\opencv\build\bin\opencv_ffmpeg310.dll
                            

                            i have only one library file in the openCV folder
                            Do you have any idea what i am suppose to do?

                            1 Reply Last reply
                            0
                            • mrdebugM Offline
                              mrdebugM Offline
                              mrdebug
                              wrote on last edited by
                              #17

                              Hi.
                              You can't use the vc libraries of OpenCV with Qt built with Mingw. If you want to use Qt with mingw you have to build OpenCV with Mingw.
                              I confirm Qt 5.5 works perfectly with OpenCV 3.
                              http://www.denisgottardello.it/ComputerVisionStudio/index.php

                              Need programmers to hire?
                              www.labcsp.com
                              www.denisgottardello.it
                              GMT+1
                              Skype: mrdebug

                              1 Reply Last reply
                              0
                              • B Offline
                                B Offline
                                beginMyCoding
                                wrote on last edited by
                                #18

                                Is there any link which explains perfect installation of OpenCV 3 and Qt5.5?

                                1 Reply Last reply
                                0
                                • mrdebugM Offline
                                  mrdebugM Offline
                                  mrdebug
                                  wrote on last edited by
                                  #19

                                  These lines of code work perfectly with Qt 5.5.0 and OpenCV 3.0
                                  set PATH=%PATH%;C:\Qt\Qt5.5.0\Tools\mingw492_32\bin;C:\Program Files (x86)\CMake 2.8\bin
                                  cmake -G "MinGW Makefiles" -DWITH_FFMPEG=OFF -DCMAKE_BUILD_TYPE=RELEASE -DBUILD_opencv_videoio=ON -DWITH_IPP=OFF -DWITH_OPENCL=OFF -DWITH_JASPER=OFF -DWITH_OPENEXR=OFF -DBUILD_SHARED_LIBS=OFF -DBUILD_TESTS=OFF -DBUILD_PERF_TESTS=OFF -DOPENCV_EXTRA_MODULES_PATH=modules/opencv_contrib-master/modules .

                                  mingw32-make -j 4

                                  I have only some problems with webcams in some 64 bit machines.

                                  Another hard problem is to setup the pro file. You have to include the libraries in a particular order (depends from your program). Some libraries can be included more than one time.
                                  This solution sounds to be very strange but I assure, to have OpenCV working I have spent a lot of time.

                                  If you need professional support please send me an email at info@denisgottardello.it

                                  Need programmers to hire?
                                  www.labcsp.com
                                  www.denisgottardello.it
                                  GMT+1
                                  Skype: mrdebug

                                  B 1 Reply Last reply
                                  0
                                  • mrdebugM mrdebug

                                    These lines of code work perfectly with Qt 5.5.0 and OpenCV 3.0
                                    set PATH=%PATH%;C:\Qt\Qt5.5.0\Tools\mingw492_32\bin;C:\Program Files (x86)\CMake 2.8\bin
                                    cmake -G "MinGW Makefiles" -DWITH_FFMPEG=OFF -DCMAKE_BUILD_TYPE=RELEASE -DBUILD_opencv_videoio=ON -DWITH_IPP=OFF -DWITH_OPENCL=OFF -DWITH_JASPER=OFF -DWITH_OPENEXR=OFF -DBUILD_SHARED_LIBS=OFF -DBUILD_TESTS=OFF -DBUILD_PERF_TESTS=OFF -DOPENCV_EXTRA_MODULES_PATH=modules/opencv_contrib-master/modules .

                                    mingw32-make -j 4

                                    I have only some problems with webcams in some 64 bit machines.

                                    Another hard problem is to setup the pro file. You have to include the libraries in a particular order (depends from your program). Some libraries can be included more than one time.
                                    This solution sounds to be very strange but I assure, to have OpenCV working I have spent a lot of time.

                                    If you need professional support please send me an email at info@denisgottardello.it

                                    B Offline
                                    B Offline
                                    beginMyCoding
                                    wrote on last edited by
                                    #20

                                    @mrdebug
                                    I seriously did not understand from 3rd line (cmake).

                                    I set the paths of Qt and CMake
                                    Below are my paths
                                    C:\Qt\5.5\mingw492_32\bin
                                    C:\CMake\bin

                                    I don't understand what I have to do in CMake?
                                    Can you say me any step by step procedure or any other way?

                                    1 Reply Last reply
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