Using QT with openCV on Maverick osX

  • Hello

    I am new to openCV and I would like to install openCV and use it with QT.
    I used macports to install it and i set the path in the terminal.

    What I did was;

    I installed macports
    I typed in the terminal
    export PATH=$PATH:/opt/local/bin
    source .profile
    sudo port -v selfupdate
    sudo port install opencv
    Thats all...

    Now i try to compile a Helloworld but i get unknown variable error. Looks like something with the linker gone wrong or i included the wrong libs? I searched google and I found some hints but nothing helped yet. Maybe someone got a suggestion?
    Thank you very much for your time and answer!

    My settings:
    # Project created by QtCreator 2014-02-04T22:10:07

    QT       += core
    QT       -= gui
    TARGET = opencvTest
    CONFIG   += console
    CONFIG   -= app_bundle
    TEMPLATE = app
    SOURCES += main.cpp
    INCLUDEPATH += /opt/local/include
    LIBS += -L/opt/local/lib
    LIBS += -lopencv_core


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

    using namespace std ;
    using namespace cv ;
    int main()
        Mat img ;
        img = imread("unknown.jpg") ;
        return 0;

    Error message

    10:39:10: Running steps for project opencvTest...
    10:39:10: Configuration unchanged, skipping qmake step.
    10:39:10: Starting: "/usr/bin/make"
    /Users/Ben/Qt/5.2.0/clang_64/bin/qmake -spec macx-g++ CONFIG+=debug CONFIG+=x86 CONFIG+=declarative_debug CONFIG+=qml_debug -o Makefile ../opencvTest/
    /Applications/ -headerpad_max_install_names -Wl,-syslibroot,/Applications/ -mmacosx-version-min=10.6 -o opencvTest main.o -F/Users/Ben/Qt/5.2.0/clang_64/lib -L/opt/local/lib -lopencv_core -framework QtCore
    Undefined symbols for architecture x86_64:
    "cv::imread(std::string const&, int)", referenced from:
    _main in main.o
    ld: symbol(s) not found for architecture x86_64
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    make: *** [opencvTest] Error 1
    10:39:10: The process "/usr/bin/make" exited with code 2.
    Error while building/deploying project opencvTest (kit: Unnamed)
    When executing step 'Make'
    10:39:10: Elapsed time: 00:00.@

  • Lifetime Qt Champion

    Hi and welcome to devnet,

    Check your opencv install to see if it was build for x86_64

  • Hmm it should be, Macport installs it as a 64bit as default as I know from google.
    I don't know how I can check that honestly.

  • Lifetime Qt Champion


    @file /opt/local/lib/libopencv_core.dylib@

    in your console

  • so....
    /opt/local/lib/libopencv_core.dylib: Mach-O 64-bit dynamically linked shared library x86_64

    thats the result so I think its the right one? isn't it?

  • Yeaah it works! Finally!


    had to change




  • BUT... other libs like boost won't work anymore...

    I have to add
    to the pro file in the project for the opencv projects separately

  • Lifetime Qt Champion

    You'll have to check that all your libraries have the same deployment target. That might also mean rebuild Qt

Log in to reply

Looks like your connection to Qt Forum was lost, please wait while we try to reconnect.