web development helpdesk

The ImageIO class provides utility classes for both read and writing images. To write your image to an output stream you would can use the write method telling it what format you want to write the image in, eg. JPEG, PNG.

ImageIO.write(image, "PNG", out);

written by objects \\ tags: BufferedImage, stream

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.

written by objects \\ tags: AffineTransform, BufferedImage

Create a ByteArrayInputStream from your byte array and then use ImageIO class to read image from that stream.

InputStream in = new ByteArrayInputStream(bytearray);
BufferedImage image = ImageIO.read(in);

written by objects \\ tags: BufferedImage, ByteArrayInputStream, image, ImageIO