How to Successfully Integrate OpenCV and Qt in Qt Creator?

Integrating OpenCV and Qt in QtCreator

Introduction

Linking OpenCV and using the Qt library in QtCreator can be a challenging task. Various tutorials and resources exist, but finding a comprehensive solution can be difficult. This article aims to provide a clear and thorough guide to accomplish this integration.

Installation and Setup

1. Install Qt 5.0.1 for Windows 32-bit (MinGW 4.7) with the following requirement: Avoid directories with white-spaces in their names. Consider creating a folder named "Programs" for all important program installations.
2. Download and install Cmake-2.8.10.2-win32-x86.exe for all users.
3. Download OpenCV-2.4.0.exe and extract to C:Programsopencv24, creating two subdirectories named "opencv" and "opencv_bin."
4. Configure PATH environment variable to include the MinGW compiler: C:ProgramsQtQt5.0.1ToolsMinGWbin;

Creating OpenCV Binaries

1. Launch cmake-gui.exe and configure the source code directory to C:Programsopencv24opencv and the binaries directory to C:Programscopencv24opencv_bin.
2. Specify native compilers for C and C using the paths: C:/Programs/Qt/Qt5.0.1/Tools/MinGW/bin/gcc.exe and C:/Programs/Qt/Qt5.0.1/Tools/MinGW/bin/g .exe.
3. Select WITH_QT and unselect WITH_TBB, WITH_IPP, and WITH_CUDA.
4. Set CMAKE_BUILD_TYPE to "Debug."
5. Click "Configure" until all red lines disappear.
6. Click "Generate" and close cmake-gui.exe.
7. Open a command prompt, navigate to the opencv_bin directory, and execute "mingw32-make" and "mingw32-make install."

QtCreator Project Configuration

1. Create a new QtCreator Console application.
2. Configure the .pro file as follows:

QT       += core
QT       -= gui

TARGET = cvHello
CONFIG   += console
CONFIG   -= app_bundle

TEMPLATE = app
INCLUDEPATH += C:/Programs/opencv24/opencv_bin2/install/include
LIBS += "C:/Programs/opencv24/opencv_bin2/bin/*.dll"

SOURCES += main.cpp
OTHER_FILES += \
    img.JPG

3. Define the main.cpp file as follows:

#include <iostream>
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv/cv.h"

using namespace std;

int main()
{
    cout << "Hello World!" << endl;

    cv::Mat mat;
    mat = cv::imread("img.JPG");
    cvNamedWindow("hello");
    cv::imshow("hello",mat);

    cvWaitKey(0);

    return 0;
}

4. Ensure that the path to QtCreator/bin is included in the PATH variable.

Alternative Library Linking

Instead of using "*.dll," you can manually list the necessary libraries in the LIBS variable:

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

This alternative method can also resolve any issues when listing the DLLs manually.

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