ImageUrl = "GaugeImages/#CLIENT_#SESSION.#EXT" (this would store images in a folder named GaugeImages under the current page's folder). ImageUrl = "../GaugeImages/#CLIENT_#SESSION.#EXT" (this would store images in a folder named GaugeImages, one directory up from the current page's folder). ImageUrl = "/GaugeImages/#CLIENT_#SESSION.#EXT" (this would store images in the folder C:\inetpub\wwwroot\GaugeImages).