<%@ Page language="c#" %>
<%@ Import Namespace="System.Drawing" %>
<%@ Import Namespace="System.Drawing.Imaging" %>
<script language="c#" runat="server">
private void Page_Load(object sender, System.EventArgs e)
  {

   // 设置 mime 类型为image/jpeg，即将向浏览器输出JPGE格式的图像
   Response.Clear();
   Response.ContentType="image/jpeg";
   Bitmap OutputBitmap = new Bitmap(Server.MapPath("source.bmp"));//新建BitMap对象
   System.Drawing.Imaging.EncoderParameters encoderParams = new System.Drawing.Imaging.EncoderParameters();
   long[] quality = new long[1];
  
   int comp = 0;
   if (Request.QueryString["comp"] != "") { comp = Convert.ToInt16(Request.QueryString["comp"]); }
   quality[0] = comp; //0 to 100 最高质量为100
   System.Drawing.Imaging.EncoderParameter encoderParam = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
   encoderParams.Param[0] = encoderParam;

   ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();//获得包含有关内置图像编码解码器的信息的ImageCodecInfo 对象。
   ImageCodecInfo jpegICI = null;
   for (int x = 0; x < arrayICI.Length; x++)
   {
    if (arrayICI[x].FormatDescription.Equals("JPEG"))
    {
     jpegICI = arrayICI[x];//设置JPEG编码
     break;
    }
   }
   if (jpegICI != null)
   {
    OutputBitmap.Save(Response.OutputStream, jpegICI, encoderParams);//将位图对象以流格式并用JPEG编解码参数保存到输出流。
   }
   // clean up
   OutputBitmap.Dispose();
  }
</script>