void getImageFromWebsite1(url)
        {
            string filepath = "F:\\pic.jpg";
            WebClient mywebclient = new WebClient();
            mywebclient.DownloadFile(url, filepath);
        }
        void getImageFromWebsite2(url)
        {
            WebRequest request = WebRequest.Create(url);
            WebResponse response = request.GetResponse();
            Stream reader = response.GetResponseStream();
            FileStream writer = new FileStream("F:\\pic.jpg", FileMode.OpenOrCreate, FileAccess.Write);
            byte[] buff = new byte[512];
            int c = 0; 
            while ((c = reader.Read(buff, 0, buff.Length)) > 0)
            {
                writer.Write(buff, 0, c);
            }
            writer.Close();
            writer.Dispose();
            reader.Close();
            reader.Dispose();
            response.Close();
        }