Mark Stephens Mark has been working with Java and PDF since 1999 and is a big NetBeans fan. He enjoys speaking at conferences. He has an MA in Medieval History and a passion for reading.

How to resize images in Java

1 min read

image formats 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

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);

Why use JDeli process Images in Java?

JDeli offers a range of advantages over ImageIO and alternatives, including:

  • prevent heap related JVM crashes
  • support for additional image formats such as Heic
  • reduce the output file size
  • improve read/write performance
  • create smaller files
  • control over output
  • support threading
  • superior image scaling algorithms



Tired of bad quality image libraries?

Write and Read Images in Java Find out why our customers trust JDeli with reading/writing images in Java

Mark Stephens Mark has been working with Java and PDF since 1999 and is a big NetBeans fan. He enjoys speaking at conferences. He has an MA in Medieval History and a passion for reading.

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