How to resize images in Java

In this article, I will show you how to resize images in Java.

ImageIO allows the reading and writing of images in Java and processing the image. I will also cover image resizing using our JDeli image library.

How to resize an image in ImageIO

1. Create a File handle, InputStream, or URL pointing to the raw image.
2. ImageIO will now be able to read a BMP file into a BufferedImage. This syntax is like so:

   BufferedImage image = ImageIO.read(bmpFileOrInputStreamOrURL)

3. Create a second BufferedImage at the new size

   final int w = image.getWidth();
   final int h = image.getHeight();
   BufferedImage scaledImage = new BufferedImage((w * 2),(h * 2), BufferedImage.TYPE_INT_ARGB);

4. Create a transformation

   final AffineTransform at = AffineTransform.getScaleInstance(2.0, 2.0);
   final AffineTransformOp ato = new AffineTransformOp(at, AffineTransformOp.TYPE_BICUBIC);

5. Apply the transformation

   scaledImage = ato.filter(image, scaledImage);

How to resize an image in JDeli

1. Add JDeli to your class or module path. (download the trial jar).
2. Create a File, InputStream pointing to the raw image. You can also use a byte[] containing the image data.
3. Read the image into a BufferedImage

   BufferedImage image = JDeli.read(bmpFile);

4. Create a transformation

   ImageProcessingOperations operations = new ImageProcessingOperations();
   operations.scale(scalingFactor);

5. Apply the transform

   image = JDeli.process(ImageProcessingOperations operations, 
   BufferedImage image);

Why do developers choose JDeli over free alternatives?

1. Works with newer image formats such as AVIF, HEIC, JPEG XL, WEBP (AVIF next release) that are not supported in Java.
2. Better support than alternatives for JPEG, PNG, TIFF.
3. Process images up to 3x faster than ImageIO and other Java image libraries.
4. Prevent JVM crashes caused by native code in other image libraries such as ImageIO.
5. Image security as JDeli processes images on your servers with no calls to any external system or third party library.

// Read an image
BufferedImage bufferedImage = JDeli.read(dicomImageFile);

// Read an image
BufferedImage bufferedImage = JDeli.read(heicImageFile);

// Write an image
JDeli.write(bufferedImage, "heic", outputStreamOrFile);

// Read an image
BufferedImage bufferedImage = JDeli.read(jpegImageFile);

// Write an image
JDeli.write(bufferedImage, "jpeg", outputStreamOrFile);

// Read an image
BufferedImage bufferedImage = JDeli.read(jpeg2000ImageFile);

// Write an image
JDeli.write(bufferedImage, "jpx", outputStreamOrFile);

// Write an image
JDeli.write(bufferedImage, "pdf", outputStreamOrFile);

// Read an image
BufferedImage bufferedImage = JDeli.read(pngImageFile);

// Write an image
JDeli.write(bufferedImage, "png", outputStreamOrFile);

// Read an image
BufferedImage bufferedImage = JDeli.read(tiffImageFile);

// Write an image
JDeli.write(bufferedImage, "tiff", outputStreamOrFile);

// Read an image
BufferedImage bufferedImage = JDeli.read(webpImageFile);

// Write an image
JDeli.write(bufferedImage, "webp", outputStreamOrFile);