BufferedImage black and white after scaling

Question

After scaling BufferdImages of nation flags about 50% of all flags are displayed in black and white (not grayscale) and few do look weird, like turky:

turky

Here's a black and white example b&w

Here I set the flag

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();
}

And my 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);
    }

}

please provide a http://stackoverflow.com/help/mcve – STaefi Feb 21 '16 at 15:45 — STaefi, Feb 21 '16 at 15:45

score 0 · Accepted Answer · edited May 23 '17 at 12:19

0

I'm pretty sure you can not just change the height and width of a Buffered Image and it will scale for you. Try using getScaledInstance() like in this question.

edited May 23 '17 at 12:19

Community

1
1

answered Feb 21 '16 at 15:48

user2965346

30
2
5

Thanks, I should read more carefully because my code came from that exact question – Aeron Feb 21 '16 at 16:15

score 0 · Answer 2 · answered Feb 21 '16 at 16:19

The code bellow works fine, but you need to call the repaint method because the getScaledInstance method take a time to generate the scaloned image.

    public class Main extends JFrame {

    private ImageIcon ico;
    private boolean resize = true;
    private Image scale;

    public Main() {
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);
        ico = new ImageIcon("image.jpg");
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);

        Graphics2D gg = (Graphics2D) g;

        if (!resize) {
            g.drawImage(ico.getImage(), 0, 0, null);

        } else {
            if (scale == null) {
                scale = ico.getImage().getScaledInstance(ico.getIconWidth() / 2, ico.getIconHeight() / 2, Image.SCALE_SMOOTH);
            }

            g.drawImage(scale, 0, 0, null);

            // gg.scale(0.5, 0.5);
            // gg.drawImage(ico.getImage(), 0, 0, null);
        }

    }

    public static void main(String[] args) {
        Main m = new Main();
        m.setSize(600, 600);
        m.setVisible(true);

    }

}

BufferedImage black and white after scaling

2 Answers2