缩放后的BufferedImage黑白

Question

在缩放国家旗帜的BufferdImages之后，大约50％的旗帜以黑白（不是灰度）显示，很少看起来很奇怪，如turky：

这是一个黑白的例子

这里我设置了标志

protected void updateFlag(BufferedImage flag){
    int height = pnlFlag.getHeight();
    int width = (int)(1f * flag.getWidth() / flag.getHeight() * height);
    BufferedImage scaledFlag = new BufferedImage(width, height, flag.getType());

    Graphics2D g2d = scaledFlag.createGraphics();
    g2d.drawImage(flag, 0, 0, scaledFlag.getWidth(), scaledFlag.getHeight(), null);
    g2d.dispose();

    pnlFlag.flag = scaledFlag;
    pnlFlag.repaint();
}

我的JPanel

class FlagPanel extends JPanel{

    private BufferedImage flag;

    @Override
    protected void paintComponent(Graphics g){
        super.paintComponent(g);
        if(flag == null) return;

        g.drawImage(flag, 0, 0, null);
    }

}