You could use Sun's Java Advanced Imaging, as well. http://java.sun.com/products/java-media/jai/
JAI gives you about everything you could need to manipulate many formats of bitmap images, though the API seems daunting at first. I found one article that provides a good discussion and examples of wrapping common functions like resizing in a utility class. (The article goes on to discuss using this class from within Cold Fusion, but the java portion of the discussion would be the same regardless.) http://www.evolt.org/article/Image_Manipulation_with_CFMX_and_JAI/18/33907/ -Greg
