Poor Man's Imaging Wrapper a clean and simple API wrapper over JAI, Java2D, ImageIO, and AWT. It supports a set of imaging operations (read, write, scale/resize, crop, grayscale, add transparency, rotate, add border, flip/mirror, add text, overlay, blur, sharpen, etc.) with simple direct calls to the API. If you want to switch from Java2D to JAI, all you need to do is add JAI jars to the classpath. It supports GIF encoding if PJA tools jars are available in the classpath.
Apache XML Graphics Commons is a library that consists of several reusable components used by Apache Batik and Apache FOP. Many of these components can easily be used separately outside the domains of SVG and XSL-FO. You will find components such as a PDF library, an RTF library, Graphics2D implementations that let you generate PDF and PostScript files, and much more.