Java/ImageIO getting image dimensions without reading the entire file?

Question

Is there a way to get the dimensions of an image without reading the entire file?

URL url=new URL(<BIG_IMAGE_URL>);
BufferedImage img=ImageIO.read(url);
System.out.println(img.getWidth()+" "+img.getHeight());
img=null;

Answer 1

try(ImageInputStream in = ImageIO.createImageInputStream(resourceFile)){
    final Iterator<ImageReader> readers = ImageIO.getImageReaders(in);
    if (readers.hasNext()) {
        ImageReader reader = readers.next();
        try {
            reader.setInput(in);
            return new Dimension(reader.getWidth(0), reader.getHeight(0));
        } finally {
            reader.dispose();
        }
    }
} 

Thanks to sfussenegger for the suggestion

Answer 2

Using ImageReader.getHeight(int) and ImageReader.getWidth(int) normally only reads the image header (I'm looking at JDK6 sources). So ImageReader is most likely the best choice.

Answer 3

You'll have to look into ImageReader.getImageMetadata(). Unfortunately, The Java Image API is not at all easy to use.

You can find descriptions of the metadata formats in the package documentation of javax.imageio.metadata.

There are third party libraries that are easier to use, such as MediaUtil (last updated 3 years ago, but it worked well for me).

Answer 4

The solution with ImageInputStream and ImageReader is still not so efficient though because they create tmp files. It becomes much slower when image is larger or concurrency is higher, i recommend to use metadata-extractor instead.