C# 通过WebRequest去访问一个图片的url连接如何读取图片

WebRequest webRequest = WebRequest.Create("http://nd.fjsen.com/images/attachement/jpg/site162/20120313/00248c4cdbd010c9321004.jpg");
            HttpWebRequest request = webRequest as HttpWebRequest;
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            string encoding = response.ContentEncoding;
            StreamReader reader = new StreamReader(response.GetResponseStream());
            var xx = reader.ReadToEnd();
            byte[] picbyte = Encoding.Default.GetBytes(xx);