读取网络上的图片转成Image有关问题

Stream stream = null;        StreamReader reader = null;        MemoryStream ms = null;        HttpWebResponse webResponse = null;        try        {            WebRequest webRequest = HttpWebRequest.Create("http://image.sjq.cn/img/201002/99913/1213.jpg");   //打开图片地址            webResponse = (HttpWebResponse)webRequest.GetResponse();            stream = webResponse.GetResponseStream();            reader = new StreamReader(stream);            string textContent = reader.ReadToEnd();            byte[] bytes = System.Text.Encoding.Default.GetBytes(textContent);            ms = new MemoryStream(bytes);            System.Drawing.Image img = System.Drawing.Image.FromStream(ms);             [color=#FF0000] ms参数无效[/color]            //记录是否是图片个格式            bool imgState = false;            if (img.RawFormat == ImageFormat.Gif)                imgState = true;            if (img.RawFormat == ImageFormat.Jpeg)                imgState = true;            if (img.RawFormat == ImageFormat.Png)                imgState = true;            if (imgState)            {                imgHeight = img.Height;                imgWidth = img.Width;                imgSize = int.Parse(img.Size.ToString());                md5 = getMd5Hash(textContent);                if (ImagesManager.GetImgMarkIsExits(md5))                {                    message = "该图片已经存在!";                    return false;                }                return true;            }            else            {                message = "该URL地址的目标不是图片";                return false;            }        }        catch (Exception ex)        {            message = ex.Message;            message = "图片上传操作异常";            return false;        }        finally        {            webResponse.Close();            stream.Dispose();            stream.Close();            reader.Dispose();            reader.Close();            ms.Dispose();            ms.Close();        }