Convert PNG to JPEG image in Java

This article shows how to convert an PNG image format to an JPEG image format in Java.

1. PNG Image

Below is a PNG image with a transparent background.

2. Java Convert PNG to JPEG

Since the JPEG image format doesn’t support the transparent background, we will create a white background as a replacement. Below is a complete Java example of converting a PNG image to a JPEG image.

Key information for BufferedImage:

JPEG needs BufferedImage.TYPE_INT_RGB
PNG needs BufferedImage.TYPE_INT_ARGB

ConvertPngToJpg.java


package com.mkyong.io.image;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;

public class ConvertPngToJpg {

    public static void main(String[] args) throws IOException {

        Path source = Paths.get("C:\\test\\javanullpointer.png");
        Path target = Paths.get("C:\\test\\new.jpg");

        BufferedImage originalImage = ImageIO.read(source.toFile());

        // jpg needs BufferedImage.TYPE_INT_RGB
        // png needs BufferedImage.TYPE_INT_ARGB

        // create a blank, RGB, same width and height
        BufferedImage newBufferedImage = new BufferedImage(
                originalImage.getWidth(),
                originalImage.getHeight(),
                BufferedImage.TYPE_INT_RGB);

        // draw a white background and puts the originalImage on it.
        newBufferedImage.createGraphics()
                .drawImage(originalImage,
                        0,
                        0,
                        Color.WHITE,
                        null);

        // save an image
        ImageIO.write(newBufferedImage, "jpg", target.toFile());

    }

}

A JPEG file with a white background.

The background can be any color, below snippet change the background to gray color.


newBufferedImage.createGraphics()
        .drawImage(originalImage,
                0,
                0,
                Color.GRAY,
                null);

Further Reading
For more examples of BufferedImage, please refer to this example – How to resize an image in Java

Download Source Code

$ git clone https://github.com/mkyong/core-java

$ cd java-io

References

Written by mkyong

Software Engineer • Writer • Dad

20+ years hands-on, writing about Java, Spring, and AI. Every code example here is tested.

All posts by mkyong

7 comments on “Convert PNG to JPEG image in Java”

Satheeshraj V

November 10, 2014 at 2:14 am

Hi,
I need the code to convert .gif image with transparent background to resized .jpg image ..I tried with different possibilities in the internet but no luck .I’m always getting the black image .please help me to resolve it.

Regards,
Satheesh

anonymous
August 5, 2015 at 3:12 pm

Just make sure you are not using
this : BufferedImage.TYPE_INT_ARGB

Reply

Alex Arriaga

December 8, 2013 at 6:33 am

Thanks, it works like a charm!

Chandra Mani Gupta

October 28, 2013 at 4:35 pm

Thanks dude.

David

September 24, 2012 at 3:43 am

Hey thanks for sharing the source. Does this only work for small image conversions? What if you have a 2448×3264 PNG image (~13 MB) for converting to JPEG? Trying th code, it threw exception with Java out of memory error with heap space.

mkyong Author
September 24, 2012 at 11:34 am

Then increase your memory for Java program.

Reply
1. Habibur
  August 5, 2022 at 4:55 pm
  
  Is there any library that use disk instead of memory. It will worst when server has many users concurrent .
  
  Reply