How to write PNG Images in Java (Tutorial)

In this article, I will show you how to write PNG images in Java. We also have a related article covering how to read PNG files in Java. I will look at two methods for PNG image processing with Java, using ImageIO and our JDeli image library.

ImageIO is able to write PNG files, but it offers very little control over the PNG output and produces very large PNG files. So we will also show you our JDeli image library, which can produce much smaller PNG images.

How to write out an image as a PNG file in ImageIO

1. Create a File (or OutputStream) object for the PNG output.
2. Pass image, png type and File (or OutputStream) object into write method

and the Java code to write PNG with ImageIO…

File file = new File("/path/to/outputFile.png");
ImageIO.write(bufferedImage, "PNG", file);

How to write out an image as PNG with JDeli

1. Add JDeli to your class or module path. (download link to the free trial jar).
2. Create a File (or OutputStream) object
3. Pass image, PNG type and File (or OutputStream) object into write method

and the Java code to write PNG with JDeli…

File file = new File("/path/to/outputFile.png");
JDeli.write(bufferedImage, "PNG", file);

//In JDeli you can also use a typesafe version
JDeli.write(bufferedImage, OutputFormat.PNG, file);
or pass in a PngEncoderOptions object for more control over PNG image output

PngEncoderOptions options = new PngEncoderOptions();
JDeli.write(bufferedImage, options, file);

In this example, my original file was a jpg image, and I used JDeli to write it out as a png image:

// 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);