c#將圖片Image轉換為內存流MemoryStream

HttpWebResponse resp = (HttpWebResponse)wRequest.GetResponse();
Stream stream = resp.GetResponseStream();
Image img = Image.FromStream(stream);
byte[] back = null;
MemoryStream memoryStream = new MemoryStream();
img.Save(memoryStream, ImageFormat.Jpeg);
back = memoryStream.GetBuffer();
string str = Convert.ToBase64String(back);