Image size from header

Question

Hi,
I'm trying to extract image size from header for PNG, JPG, TIFF, BMP and GIF files. So far I got PNG working. I'm having problems finding size info for JPG files. Anyone knows where I can read about it (i didnt find nothing on google) or have the code that works? also for the other image types?
P.S. I dont wanna read the entire image using Image class cause its too slow.

Answer 1

Code Snippet:
ImageInputStream imageStream =
        ImageIO.createImageInputStream(/*File or InputStream*/);
java.util.Iterator<ImageReader> readers =
        ImageIO.getImageReaders(imageStream);
ImageReader reader = null;
if(readers.hasNext()) {
    reader = readers.next();
}else {
    imageStream.close();
    //can't read image format... what do you want to do about it,
    //throw an exception, return ?
reader.setInput(imageStream,true,true);
int imageWidth = reader.getWidth(0);
int imageHeight = reader.getHeight(0);
reader.dispose();
imageStream.close();