Create a Thumbnail

What does it do?

Create a copy of the image with the specified dimensions. This operation uses a scaling routine designed to produce best output when the specified dimensions are smaller than the original.

Scale a BufferedImage in Java

Add JDeli to your project via Maven or Gradle, or see using JDeli with Java modules.

ImageProcessingOperations uses a builder pattern — chain transformation methods to define how the image should be processed, then pass the object to JDeli.convert() to apply them during format conversion.

ImageProcessingOperations operations = new ImageProcessingOperations();

// Chain multiple operations such as scale, blur, rotate, sharpen, and more
operations.thumbnail(64, 64); 
        
// Apply the operations to a BufferedImage
BufferedImage modifiedImage = operations.apply(BufferedImage originalImage);

View Javadoc for the thumbnail operation

JDeli.convert() — Input/Output Methods

Pass an ImageProcessingOperations object to any JDeli.convert() overload to apply transformations during conversion. JDeli supports three input/output models:

Using File

Read from and write to disk paths directly.

File inputFile = new File("path/to/file");
File outputFile = new File("path/to/output-thumbnail-file");
JDeli.convert(inputFile, outputFile, operations);

Using InputStream and OutputStream

Use for network streams, servlet responses, or any scenario where file paths are unavailable.

final InputStream inputStream = new FileInputStream(inputFile);
final OutputStream outputStream = new FileOutputStream(outputFile);
final String outputFormat = "png"; // Supported formats: avif, bmp, gif, heic, jpeg, pdf, png, tiff, webp
JDeli.convert(inputStream, outputStream, outputFormat, operations);

Using byte[]

Use for in-memory processing pipelines where data is already loaded.

byte[] inputData = Files.readAllBytes(Paths.get("/path/to/file"));
final String outputFormat = "png"; // Supported formats: avif, bmp, gif, heic, jpeg, pdf, png, tiff, webp
byte[] outputData = JDeli.convert(inputData, outputFormat, operations);

Frequently Asked Questions

Can I chain multiple image processing operations together?

Yes. ImageProcessingOperations is a builder — call as many methods as needed before passing the object to JDeli.convert(). Operations are applied in the order they are chained.

Can I apply operations without converting the image format?

Yes. Call operations.apply(BufferedImage originalImage) directly to get a processed BufferedImage without any format conversion.

Which input types does JDeli support for image processing?

JDeli supports File, InputStream/OutputStream, and byte[]. All three overloads of JDeli.convert() accept an ImageProcessingOperations parameter.

What output formats can I convert to when applying operations?

JDeli can write to AVIF, BMP, GIF, HEIC, JPEG, PDF, PNG, TIFF, and WebP when using JDeli.convert() with an ImageProcessingOperations object.