WEB下的GDI+绘图输出解决图像模糊

using System.IO

   Graphics objGraphics;
   Bitmap objBitmap = new Bitmap(W, H);
   objGraphics = Graphics.FromImage(objBitmap);

   ......

   //说明：如果直接以ＪＰＥＧ或ＧＩＧ输出的话，图片效果模糊不清
   MemoryStream tempStream = new MemoryStream();
   Response.ContentType = "Image/png";
   objBitmap.Save(tempStream, ImageFormat.Png);
   Response.BinaryWrite(tempStream.ToArray());
   objGraphics.Dispose();
   objBitmap.Dispose();
   this.Response.End();