Display a wait gif while an Image is generated and loads from an ASHX page

I need the code to show a wait image in the center of a slightly grayed out screen while it load an image from an ashx page. the url is [login to view URL] And that will generate the image for you. My current code is var d = new Date(); var n = [login to view URL](); $("#theImg").attr("src", "[login to view URL]" + n); The time is needed to prevent cache. I know that jQuery has an load event and I need something that will work. I don't have time to Google for an answer and would rather give it to a person that knows what they are going. It should be a very short sample that I would pull into my app. Thanks