I have in my project a page DownloadDocument.aspx and it\'s codebhind is DownloadDocument.aspx.cs
In my DownloadDocument.aspx
it depends on type of file you are trying to download...because every request is gone through HTTPHandler's ProcessRequest. and it's checks each and every request one by one..
You need to add any HTTPHandler to your project and need to add something like this in your web.config.
This will check your request for every Image type.. mentioned in path attribute
Edit :