关于asp.net上传图片生成缩略图不清晰的问题

use a high InterpolationMode, for example
from 
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=OC6Oj2F%24CHA.2208%40TK2MSFTNGP12.phx.gbl
System.Drawing.Image image =
System.Drawing.Image.FromFile(originalFilename);
System.Drawing.Size size = GetImageSize(image.Width, image.Height,
information.MaximumDimension);
System.Drawing.Image bitmap = new System.Drawing.Bitmap(size.Width,
size.Height);
System.Drawing.Graphics graphics =
System.Drawing.Graphics.FromImage(bitmap);
graphics.InterpolationMode =
System.Drawing.Drawing2D.InterpolationMode.High;
graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
graphics.Clear(information.BackgroundColor);
graphics.DrawImage(image, new System.Drawing.Rectangle(0, 0, bitmap.Width,
bitmap.Height), new System.Drawing.Rectangle(0, 0, image.Width,
image.Height), System.Drawing.GraphicsUnit.Pixel);
graphics.Dispose();