Dec 03

How do I scale or resize a BufferedImage?

java 13 Comments »

There are two main ways to scale an image.

The first is to ‘paint’ a scaled version of the image to a new image of the required size.

// Create new (blank) image of required (scaled) size

BufferedImage scaledImage = new BufferedImage(
   width, height, BufferedImage.TYPE_INT_ARGB);

// Paint scaled version of image to new image

Graphics2D graphics2D = scaledImage.createGraphics();
graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
	RenderingHints.VALUE_INTERPOLATION_BILINEAR);
graphics2D.drawImage(image, 0, 0, width, height, null);

// clean up

graphics2D.dispose();

The second is to use an AffineTransform

BufferedImage scaledImage = new BufferedImage(
	width, height, BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics2D = scaledImage.createGraphics();
AffineTransform xform = AffineTransform.getScaleInstance(scale, scale);
graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
	RenderingHints.VALUE_INTERPOLATION_BICUBIC);
graphics2D.drawImage(image, xform, null);
graphics2D.dispose();

There’s also a getScaledInstance() method of the Image class which has been around since the early days of Java. Generally its worth avoiding for performance reasons.

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