Resize a picture to fit a JLabel

Question

Outline

Here are the steps to follow.

• Read the picture as a BufferedImage.
• Resize the BufferedImage to another BufferedImage that's the size of the JLabel.
• Create an ImageIcon from the resized BufferedImage.

You do not have to set the preferred size of the JLabel. Once you've scaled the image to the size you want, the JLabel will take the size of the ImageIcon.

Read the picture as a BufferedImage

BufferedImage img = null;
try {
    img = ImageIO.read(new File("strawberry.jpg"));
} catch (IOException e) {
    e.printStackTrace();
}

Resize the BufferedImage

Image dimg = img.getScaledInstance(label.getWidth(), label.getHeight(),
        Image.SCALE_SMOOTH);

Make sure that the label width and height are the same proportions as the original image width and height. In other words, if the picture is 600 x 900 pixels, scale to 100 X 150. Otherwise, your picture will be distorted.

Create an ImageIcon

ImageIcon imageIcon = new ImageIcon(dimg);

You can try it:

ImageIcon imageIcon = new ImageIcon(new ImageIcon("icon.png").getImage().getScaledInstance(20, 20, Image.SCALE_DEFAULT));
label.setIcon(imageIcon);

Or in one line:

label.setIcon(new ImageIcon(new ImageIcon("icon.png").getImage().getScaledInstance(20, 20, Image.SCALE_DEFAULT)));

The execution time is much more faster than File and ImageIO.

I recommend you to compare the two solutions in a loop.

public static void main(String s[]) 
  {

    BufferedImage image = null;
    try 
    {
        image = ImageIO.read(new File("your image path"));

    } catch (Exception e) 
    {
        e.printStackTrace();
    }

    ImageIcon imageIcon = new ImageIcon(fitimage(image, label.getWidth(), label.getHeight()));
    jLabel1.setIcon(imageIcon);
}


private Image fitimage(Image img , int w , int h)
{
    BufferedImage resizedimage = new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);
    Graphics2D g2 = resizedimage.createGraphics();
    g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
    g2.drawImage(img, 0, 0,w,h,null);
    g2.dispose();
    return resizedimage;
}

The best and easy way for image resize using Java Swing is:

jLabel.setIcon(new ImageIcon(new javax.swing.ImageIcon(getClass().getResource("/res/image.png")).getImage().getScaledInstance(200, 50, Image.SCALE_SMOOTH)));

For better display, identify the actual height & width of image and resize based on width/height percentage