PhiLho and corgrath provide Java code examples illustrating conversion of a background color to a transparent background for an image in the StackOverflow thread How to make a color transparent in ...

Java Community Process now open, transparent, and agile (or not) how-to May 29, 2009 2 mins Open Source ...

If you can't overlay transparent jpanel then you should minimize the re-drawing to the areas affected. (Depending on how stacked jpanels work it may still be faster for you to do it this way ...