public void MakeSmallImg(string FromImg,string SaveImg,System.Double Width,System.Double Height) {
 /*
 System.Drawing.Image Image=System.Drawing.Image.FromFile(FromImg);
 */
 //原始图片名称
 string originalFilename =FromImg;
 //生成的高质量图片名称
 string strGoodFile =SaveImg;

 //从文件取得图片对象
 System.Drawing.Image image = System.Drawing.Image.FromFile(originalFilename);
 System.Double NewWidth,NewHeight;
 if(image.Width>image.Height) {
  NewWidth=Width;
  NewHeight=image.Height*(NewWidth/image.Width);
 } else {
  NewHeight=Height;
  NewWidth=(NewHeight/image.Height)*image.Width;
 }

 if (NewWidth>Width) {
  NewWidth=Width;
 }
 if (NewHeight>Height) {
  NewHeight=Height;
 }

 //取得图片大小
 System.Drawing.Size size = new Size(int.Parse(ClDot(NewWidth.ToString())),int.Parse(ClDot(NewHeight.ToString())));
 //新建一个bmp图片
 System.Drawing.Image bitmap = new System.Drawing.Bitmap(size.Width,size.Height);
 //新建一个画板
 System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
 //设置高质量插值法
 g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
 //设置高质量,低速度呈现平滑程度
 g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
 //清空一下画布
 g.Clear(Color.Blue);
 //在指定位置画图
 g.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);

 ///文字水印
 System.Drawing.Graphics G=System.Drawing.Graphics.FromImage(bitmap);
 System.Drawing.Font f=new Font("宋体",10);
 System.Drawing.Brush b=new SolidBrush(Color.Black);
 G.DrawString(MarkText,f,b,10,10);
 G.Dispose();

 ///图片水印
 System.Drawing.Image copyImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath(MarkLogo));
 Graphics a = Graphics.FromImage(bitmap);
 a.DrawImage(copyImage, new Rectangle(bitmap.Width-copyImage.Width,bitmap.Height-copyImage.Height,copyImage.Width, copyImage.Height),0,0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);

 copyImage.Dispose();
 a.Dispose();
 copyImage.Dispose();

 //保存高清晰度的缩略图
 bitmap.Save(strGoodFile, System.Drawing.Imaging.ImageFormat.Jpeg);

 g.Dispose();
 image.Dispose();
}