Compress image size using Java

Question

I want to compress(reduce) image size using Java. We can upload images in jpg/jpeg/png formats. The general format of images is PNG. So, after image uploaded to the server, we need to compress(reduce file size) and convert it to PNG.

I have the next code for the compress image:

    BufferedImage bufferedImage = ImageIO.read(inputStream);
    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

    switch (imageType) {
        case PNG:
        case JPG:
            // need Java 9+ for PNG writer support
            ImageWriter writer = ImageIO.getImageWritersByFormatName(imageType.getExtension()).next();
            ImageOutputStream ios = ImageIO.createImageOutputStream(outputStream);
            writer.setOutput(ios);

            ImageWriteParam param = writer.getDefaultWriteParam();
            if (param.canWriteCompressed()) {
                param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
                param.setCompressionQuality(0.3f);
            }

            writer.write(null, new IIOImage(bufferedImage, null, null), param);
            writer.dispose();
            return new ByteArrayInputStream(outputStream.toByteArray());
        default:
            log.warn("Image type unknown");
            return null;
    }

The problem is - after processing the image, I got the result - file size increased instead of reducing. The original image has a lower size than compressed. Any suggestions on how to solve this issue?

What kind of images are you dealing with? PNG may not be the best choice for every kind of image (e.g. photos). — Michael
@Michael on server all images saved in PNG. But the user can upload jpg/jpeg and png. It is images like user profile images, user post images, albums and etc. — Volodymyr Zavada
Does the compression need to be lossless? If so, maybe you can use WebP instead of PNG? — Michael

Joop Eggen Joop Eggen · Accepted Answer · 2020-01-09T16:38:42

Unfortunately the lossy JPEG compression compresses far better than the lossless PNG compression. You could restrict width and height of the image and scale proportionally.

So I would switch to JPEG and restrict the size.

Compress image size using Java

2 Answers