It sounds like you will need to write a custom cell renderer or editor to
accomplish that. This article will give you the basics of how to write cell
renderers and editors:
http://java.sun.com/docs/books/tutorial/uiswing/components/table.html.

This article is more advanced and gives considerably more information on how
cell renderers and editors work:
http://www-128.ibm.com/developerworks/library/j-jtable/. It doesn't actually
talk about how you can change background images within a renderer or editor
but you will probably be able to reason out how to do that from this
article.

--
Rhino