OpenCV with Qt in Linux(Ubuntu) - 리눅스(우분투)에서 Qt로 OpenCV 이미지 디스플레이

리눅스(우분투)에서 OpenCV 이미지(cv::Mat)를 Qt로(QImage::QImage) 디스플레이 해 보자.

(cv::Mat ↔  QImage::QImage)

 

#include <QApplication>
#include <QWidget>
#include <QPainter>
#include <opencv2/opencv.hpp>
 
class Picture : public QWidget
{
public:
    Picture(QWidget* parent = 0);
    ~Picture();
 
protected:
    void paintEvent(QPaintEvent* event);
    // This event handler can be reimplemented in a subclass to receive paint events passed in event.
    void drawPicture(QPainter* qp);
    QImage Mat2QImage(cv::Mat const& src);
    cv::Mat QImage2Mat(QImage const& src);
 
private:
    int height;
    int width;
    QImage qtImage;
    cv::Mat cvImage;
};
 
Picture::Picture(QWidget* parent) : QWidget(parent)
{
    //image.load("Barbara Palvin.png");
    //cvimage = QImage2Mat(image);
 
    //Read images from OpenCV. Not from Qt.
    cvImage = cv::imread("Barbara Palvin.png", cv::IMREAD_COLOR);
    if (cvImage.empty())
    {
        std::cerr << "Image load failed." << std::endl;
 
        exit(EXIT_FAILURE);
    }
 
    cv::Mat tempCvImage;
    cv::cvtColor(cvImage, tempCvImage, cv::COLOR_RGB2GRAY);
 
    qtImage = Mat2QImage(tempCvImage);
    tempCvImage = QImage2Mat(qtImage);
 
    cv::resize(tempCvImage, tempCvImage, cv::Size(), 1.5, 1.5);
    cv::imshow("OpenCV", tempCvImage);
 
    height = qtImage.height();
    width = qtImage.width();
 
    this->resize(width, height);
}
 
Picture::~Picture()
{
 
}
 
void Picture::paintEvent(QPaintEvent* e)
{
    Q_UNUSED(e);
    // Q_UNUSED( name)
    // Indicates to the compiler that the parameter with the specified name is not used in the body
    // of a function. This can be used to suppress compiler warnings while allowing functions to be
    // defined with meaningful parameter names in their signatures.
 
    QPainter qp(this);
    drawPicture(&qp);
}
 
void Picture::drawPicture(QPainter* qp)
{
    qp->drawImage(0, 0, qtImage);
}
 
QImage Picture::Mat2QImage(cv::Mat const& src)
{
    cv::Mat temp;
    cv::cvtColor(src, temp, cv::COLOR_BGR2RGB);
    QImage dest((const uchar*)temp.data, temp.cols, temp.rows, temp.step, QImage::Format_RGB888);
    dest.bits();
    // Enforce deep copy
    // See documentation of QImage::QImage (const uchar * data, int width, int height, Format format)
 
    return dest;
}
 
cv::Mat Picture::QImage2Mat(QImage const& src)
{
    cv::Mat temp(src.height(), src.width(), CV_8UC3, (uchar*)src.bits(), src.bytesPerLine());
    cv::Mat result; // Deep copy
    cv::cvtColor(temp, result, cv::COLOR_BGR2RGB);
 
    return result;
}
 
int main(int argc, char* argv[])
{
    QApplication app(argc, argv);
 
    Picture window;
    window.setWindowTitle("Qt");
    //window.resize(width, height);
 
    window.show();
 
    return app.exec();
}

 

소스를 입력한다. (qtcv.cpp)

 

컴파일(빌드)하고 실행하면 cv::imshow(), QPainter::drawImage() 모두 잘 표시된다. (OpenCV는 50% 확대)