QString fileName = QFileDialog::getOpenFileName(this,
    tr("Load Image"), "",
    tr("Images (*.png *.bmp *.jpg *.tif *.GIF);;All Files (*)"));
if (fileName.isEmpty()) {
    return;
}
QImageReader reader(fileName);
const QImage newImage = reader.read();
if (newImage.isNull()) {
    QMessageBox::information(this, QGuiApplication::applicationDisplayName(),
        tr("Cannot load %1: %2")
        .arg(QDir::toNativeSeparators(fileName), reader.errorString()));
    return;
}
const QPixmap pix = QPixmap::fromImage(newImage);
ui.imgLable->setPixmap(pix.scaled(size,Qt::IgnoreAspectRatio)));

QString fileName = QFileDialog::getSaveFileName(this,
        tr("Save Image"), "",
        tr("Images (*.png *.bmp *.jpg *.tif *.ppm *.GIF);;All Files (*)"));
if (fileName.isEmpty()) {
    return;
}
image0.save(fileName);