cv::Mat to QPixmap

opencv2qt

    cv::Mat n = ...
    
    QPixmap p = QPixmap::fromImage(QImage((unsigned char*) n.data,
                                   n.cols,
                                   n.rows,
                                   QImage::Format_RGB888));
    p = p.scaledToWidth(500);
    
    label->setPixmap( p );