Creating a GUI application using QT

Create new project...And chooseQt GUI application

Specifying the opencv library files and header files location (with extension. Pro)

#-------------------------------------------------## Project created by QtCreator 2012-05-29T17:22:53##-------------------------------------------------QT       += core guiTARGET = p35QtGUIapTEMPLATE = appSOURCES += main.cpp\        mainwindow.cppHEADERS  += mainwindow.hFORMS    += mainwindow.uiINCLUDEPATH += E:\OpenCV2.3.1\build\include\opencv2\INCLUDEPATH += E:\OpenCV2.3.1\build\include\opencv\INCLUDEPATH += E:\OpenCV2.3.1\build\include\LIBS += -LE:\OpenCV2.3.1\build\x86\vc10\lib \-lopencv_core231d \-lopencv_highgui231d \-lopencv_video231d \-lopencv_ml231d \-lopencv_legacy231d \-lopencv_imgproc231d

Finding a file having the extension. UI, which is the one that describes the UI Layout

Defining a CV: mat class member variable in the header file of the mainwindow class

#ifndef MAINWINDOW_H#define MAINWINDOW_H#include <QMainWindow>#include <QFileDialog>#include <opencv2/core/core.hpp>#include <opencv2/highgui/highgui.hpp>namespace Ui {class MainWindow;}class MainWindow : public QMainWindow{    Q_OBJECT    public:    explicit MainWindow(QWidget *parent = 0);    ~MainWindow();    private:    Ui::MainWindow *ui;    cv::Mat iamge; // the image variable};#endif // MAINWINDOW_H

Callback Function

void MainWindow::on_pushButton_clicked(){    QString fileName = QFileDialog::getOpenFileName(this,            tr("Open Image"),".",          tr("Image File (*.png *.jpg *.jpeg *.bmp)"));        image= cv::imread(fileName.toAscii().data());    cv::cvtColor(image,image,CV_BGR2RGB);        // Qt image    QImage img= QImage((const unsigned char*)(image.data),                           image.cols,image.rows,QImage::Format_RGB888);        // display on label    ui->label->setPixmap(QPixmap::fromImage(img));        // resize the label to fit the image    ui->label->resize(ui->label->pixmap()->size());}void MainWindow::on_pushButton_2_clicked(){    cv::flip(image,image,1);    //cv::cvtColor(image,image,CV_BGR2RGB);    // Qt image    QImage img= QImage((const unsigned char*)(image.data),                       image.cols,image.rows,QImage::Format_RGB888);    // display on label    ui->label->setPixmap(QPixmap::fromImage(img));    // resize the label to fit the image    ui->label->resize(ui->label->pixmap()->size());}

Run:

Process: