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How to Link OpenCV 2.4.9 & Qt in MacOS

asked 2014-09-11 04:12:37 -0500

Macs gravatar image

Hello there...

I have installed OpenCV using Homebrew in Mac OS Mavericks and QT Creator from the website.

I am trying to test OpenCV & QT Creator using a simple program from the internet, but I am ending up with some errors.

I donno wats going wrong.... I am new to Opencv and QT ... Your Help is much appreciated..

Below are my project details. Guide me for my first ever OpenCV & QT with Mac OS X Program......


--- File ---

QT += core

QT -= gui

TARGET = untitled1

CONFIG += console

CONFIG -= app_bundle


SOURCES += main.cpp

LIBS += -L/usr/local/Cellar/opencv/2.4.9/lib \

       -lopencv_highgui \

       -lopencv_imgproc \

       -lopencv_core \

       -lopencv_features2d \

       -lopencv_calib3d \

INCLUDEPATH += /usr/local/Cellar/opencv/2.4.9/include \

--- Source File - main.cpp ---

include opencv2/core/core.hpp

include opencv2/highgui/highgui.hpp

include iostream

include opencv/cv.h

using namespace cv;

int main()


    std::cout << "Hello World!" << std::endl;

    cv::Mat mat;

    mat = cv::imread("Unknown.JPEG");




    return 0;

--- The Compile Output with Errors ---

14:30:57: Running steps for project untitled... 14:30:57: Configuration unchanged, skipping qmake step. 14:30:57: Starting: "/usr/bin/make" /Users/Macs/Qt/5.3.1/bin/qmake -spec macx-g++ CONFIG+=debug CONFIG+=x86_64 -o Makefile ../untitled/ /Applications/ -headerpad_max_install_names -Wl,-syslibroot,/Applications/ -mmacosx-version-min=10.6 -o untitled main.o -F/usr/local/Cellar/qt5/5.3.1/lib -L/usr/local/Cellar/opencv/2.4.9/lib -lopencv_highgui -lopencv_imgproc -lopencv_core -lopencv_features2d -lopencv_calib3d -framework QtCore Undefined symbols for architecture x86_64: "cv::imread(std::string const&, int)", referenced from: _main in main.o "cv::imshow(std::string const&, cv::_InputArray const&)", 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: * [untitled] Error 1 14:30:57: The process "/usr/bin/make" exited with code 2. Error while building/deploying project untitled (kit: Desktop) When executing step "Make" 14:30:57: Elapsed time: 00:00.

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answered 2014-09-14 06:09:24 -0500

Macs gravatar image

Hi !

Gud News .... works like charm

I restored my Mac with Time Machine and I just build OpenCV 2.4.9 from the source, added Kits & Version to QT creator its working now....

I am using Mac OS X 10.9.4, OpenCV 2.4.9, and Qt Creator 3.2.0 Based on Qt 5.3.1 (Clang 5.0 (Apple), 64 bit)

Thanks for your support.... Macs

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Glad it worked out for you. Have fun :)

KellyWilson gravatar imageKellyWilson ( 2014-09-15 00:04:41 -0500 )edit

answered 2014-09-11 16:32:52 -0500

Hello Macs,

When you run into this problem of 'undefined symbols' with MacOS and opencv, I think it is because the calling conventions are different for clang++ C99 and c++11 (it shows you are calling g++ but on Mavericks that is symlinked to clang IIRC...unless you are actually using g++ installed with brew or some such...but then this error probably wouldn't happen). What you need to do is add:

QMAKE_CXXFLAGS+=-std=c++11 QMAKE_CXXFLAGS+=-stdlib=libc++

QMAKE_LFLAGS+=-std=c++11 QMAKE_LFLAGS+=-stdlib=libc++

to your .pro file. You will also need to add:


because libc++ is only supported on 10.7+. And that should fix things... YMMV ;)

Thanks, K.Wilson

P.S. Please post back if this fixes things, as it may help others.

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Thanks for your reply....will check this and revert back to you....

Macs gravatar imageMacs ( 2014-09-14 02:47:50 -0500 )edit

I got the below error on including those two line to .pro.

clang: error: no such file or directory: 'QMAKE_CXXFLAGS+=-stdlib=libc++' make: * [main.o] Error 1 13:51:31: The process "/usr/bin/make" exited with code 2. Error while building/deploying project OpencvTest (kit: Desktop) When executing step "Make"

Macs gravatar imageMacs ( 2014-09-14 03:23:09 -0500 )edit
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Asked: 2014-09-11 04:12:37 -0500

Seen: 3,280 times

Last updated: Sep 14 '14