I have written code to do this in the past. Basically what you need to write is an action that will read the image from the database and stream the binary image back. You will then use the syntax that Merrill provided to call this action (it does not give you a link).
I have heard of the DownloadAction that is included with
Struts but I have not used it (looks like since 1.2.6...I think I am using 1.1). If you are using 1.2.6 or newer, I suggest that you use DownloadAction. If you are using an older version I suggest that you download the 1.2.6 source code and look at how DownloadAction works. It is likely only about 20 lines of code.
http://struts.apache.org/1.x/struts-extras/apidocs/org/apache/struts/actions/DownloadAction.html - Brent