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
Step 1 Create a File handle, InputStream, or URL pointing to the raw image.
Step 2 ImageIO will now be able to read a BMP file into a BufferedImage. This syntax is like so:
BufferedImage image = ImageIO.read(bmpFileOrInputStreamOrURL)Step 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);Step 4 Create a transformation
final AffineTransform at = AffineTransform.getScaleInstance(2.0, 2.0);
final AffineTransformOp ato = new AffineTransformOp(at, AffineTransformOp.TYPE_BICUBIC);Step 5 Apply the transformation
scaledImage = ato.filter(image, scaledImage);How to resize an image in JDeli
Step 1 Add JDeli to your class or module path. (download the trial jar).
Step 2 Create a File, InputStream pointing to the raw image. You can also use a byte[] containing the image data.
Step 3 Read the image into a BufferedImage
BufferedImage image = JDeli.read(bmpFile);Step 4 Create a transformation
ImageProcessingOperations operations = new ImageProcessingOperations();
operations.scale(scalingFactor);Step 5 Apply the transform
image = JDeli.process(ImageProcessingOperations operations,
BufferedImage image); Read and write images in Java with one line of code
Read an Image with
BufferedImage image = JDeli.read(streamOrFile);
and write an Image with
JDeli.write(myBufferedImage, OutputFormat.HEIC, outputStreamOrFile)
Download JDeli here 
