Have you looked at
java.awt.Image yet? If not, that would probably be a good place to start.
java.awt.image.PixelGrabber might also be helpful.
These links are part of
the Java API documentation.
You should familiarize yourself with these docs and learn how to navigate them. They are a great tool to find the methods that you need, or to remind yourself what parameters and return types are used by a particular method that you are already familiar with. Note that the Java API docs are not a tutorial, though. Still, they are handy for reference. If you want tutorials to get you started on particular subjects, Sun (the makers of Java) provide some
here. There are also other available online resources, too, but I'll let you google for those.
Keep coding!
Layne