Qt5显示OpenCV图像数据

通过Qt5的label显示OpenCV图像buffer数据。

https://blog.csdn.net/qq_27278957/article/details/90638032

转换类

CV2Qt.h

#ifndef CV2QT_H
#define CV2QT_H

#include <QDebug>
#include <QImage>
#include <QPixmap>

#include "opencv2/opencv.hpp"

class CV2Qt
{
public:
    CV2Qt();
    QImage  cvMatToQImage( const cv::Mat &inMat );
    QPixmap cvMatToQPixmap( const cv::Mat &inMat );
};

#endif // CV2QT_H

CV2Qt.cpp

#include "cv2qt.h"

CV2Qt::CV2Qt()
{

}

// 将Mat转化位QImage
QImage  CV2Qt::cvMatToQImage( const cv::Mat &inMat )
{
    switch ( inMat.type() )
    {
    // 8-bit, 4 channel
    case CV_8UC4:
    {
        QImage image( inMat.data,
                      inMat.cols, inMat.rows,
                      static_cast<int>(inMat.step),
                      QImage::Format_ARGB32 );

        return image;
    }

        // 8-bit, 3 channel
    case CV_8UC3:
    {
        QImage image( inMat.data,
                      inMat.cols, inMat.rows,
                      static_cast<int>(inMat.step),
                      QImage::Format_RGB888 );

        return image.rgbSwapped();
    }

        // 8-bit, 1 channel
    case CV_8UC1:
    {
#if QT_VERSION >= QT_VERSION_CHECK(5, 5, 0)
        QImage image( inMat.data,
                      inMat.cols, inMat.rows,
                      static_cast<int>(inMat.step),
                      QImage::Format_Grayscale8 );//Format_Alpha8 and Format_Grayscale8 were added in Qt 5.5
#else//这里还有一种写法，最后给出
        static QVector<QRgb>  sColorTable;

        // only create our color table the first time
        if ( sColorTable.isEmpty() )
        {
            sColorTable.resize( 256 );

            for ( int i = 0; i < 256; ++i )
            {
                sColorTable[i] = qRgb( i, i, i );
            }
        }

        QImage image( inMat.data,
                      inMat.cols, inMat.rows,
                      static_cast<int>(inMat.step),
                      QImage::Format_Indexed8 );

        image.setColorTable( sColorTable );
#endif

        return image;
    }

    default:
        qWarning() << "CVS::cvMatToQImage() - cv::Mat image type not handled in switch:" << inMat.type();
        break;
    }

    return QImage();
}

//将Mat转化为QPixmap
QPixmap CV2Qt::cvMatToQPixmap( const cv::Mat &inMat )
{
    return QPixmap::fromImage( cvMatToQImage( inMat ) );
}

//将QImage转化为Mat
cv::Mat QImageToCvMat( const QImage &inImage, bool inCloneImageData = true )
{
    switch ( inImage.format() )
    {
    // 8-bit, 4 channel
    case QImage::Format_ARGB32:
    case QImage::Format_ARGB32_Premultiplied:
    {
        cv::Mat  mat( inImage.height(), inImage.width(),
                      CV_8UC4,
                      const_cast<uchar*>(inImage.bits()),
                      static_cast<size_t>(inImage.bytesPerLine())
                      );

        return (inCloneImageData ? mat.clone() : mat);
    }

        // 8-bit, 3 channel
    case QImage::Format_RGB32:
    case QImage::Format_RGB888:
    {
        if ( !inCloneImageData )
        {
            qWarning() << "CVS::QImageToCvMat() - Conversion requires cloning because we use a temporary QImage";
        }

        QImage   swapped = inImage;

        if ( inImage.format() == QImage::Format_RGB32 )
        {
            swapped = swapped.convertToFormat( QImage::Format_RGB888 );
        }

        swapped = swapped.rgbSwapped();

        return cv::Mat( swapped.height(), swapped.width(),
                        CV_8UC3,
                        const_cast<uchar*>(swapped.bits()),
                        static_cast<size_t>(swapped.bytesPerLine())
                        ).clone();
    }

        // 8-bit, 1 channel
    case QImage::Format_Indexed8:
    {
        cv::Mat  mat( inImage.height(), inImage.width(),
                      CV_8UC1,
                      const_cast<uchar*>(inImage.bits()),
                      static_cast<size_t>(inImage.bytesPerLine())
                      );

        return (inCloneImageData ? mat.clone() : mat);
    }

    default:
        qWarning() << "CVS::QImageToCvMat() - QImage format not handled in switch:" << inImage.format();
        break;
    }

    return cv::Mat();
}

//将QPixmap转化为Mat
cv::Mat QPixmapToCvMat( const QPixmap &inPixmap, bool inCloneImageData = true )
{
    return QImageToCvMat( inPixmap.toImage(), inCloneImageData );
}

在mainWindows中添加代码：

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    cv::Mat img = cv::imread("D:/pic/lena.jpg");
    ui->label->setPixmap(cv2qt.cvMatToQPixmap(img));
}

运行结果：

多谢，亲爱的美美。