//原始图片名称 string originalFilename = Server.MapPath("images/original.jpg"); //生成的高质量图片名称 string strGoodFile = Server.MapPath("images/small-good.jpg"); //生成的低质量图片名称 string strBadFile = Server.MapPath("images/small-bad.jpg"); //缩小的倍数 int iScale = 3; //从文件取得图片对象 System.Drawing.Image image = System.Drawing.Image.FromFile(originalFilename); //取得图片大小 System.Drawing.Size size = new Size(image.Width / iScale, image.Height / iScale); //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); //保存高清晰度的缩略图 bitmap.Save(strGoodFile, System.Drawing.Imaging.ImageFormat.Jpeg); //取得原图像的普通缩略图 System.Drawing.Image img = image.GetThumbnailImage(image.Width / iScale, image.Height / iScale, null, IntPtr.Zero); //保存普通缩略图 img.Save(strBadFile, System.Drawing.Imaging.ImageFormat.Jpeg); g.Dispose(); //MessageBox.Show("生成完毕");