the only way to accomplish that would be to use AJAX to upload the image to the server without the form being submitted. this requires hand coding and is not supported by WebAssist
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.