如何在PictureBox - 特定URL中显示Stream（Responce）中的图像

here is my codes :

这是我的代码：

    HttpWebRequest req = (HttpWebRequest)WebRequest.Create("https://www.flowercity.com/");
    req.Method = "GET";
    req.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
    req.ContentType = "text/html; charset=utf-8";
    req.Timeout = 25000;

    HttpWebResponse res = (HttpWebResponse)req.GetResponse();

    Stream Stream = res.GetResponseStream();
    StreamReader reader = new StreamReader(Stream);
    string reader_str = reader.ReadToEnd();
    HttpWebRequ