生成高清缩略图

  public void CreatePic(int width)
        {
            //本例中假定了两个变量：

            String src = @"C:\Documents and Settings\Administrator\桌面\www\WaterMark\WaterMark\images111\www\1.jpg";   //源图像文件的绝对路径

            String dest = @"C:\Documents and Settings\Administrator\桌面\www\WaterMark\WaterMark\images111\www\373737.jpg";     //生成的缩略图图像文件的绝对路径

            int thumbWidth = width;    //要生成的缩略图的宽度

            System.Drawing.Image image =  System.Drawing.Image.FromFile(src); ; //利用Image对象装载源图像
       

            //接着创建一个System.Drawing.Bitmap对象，并设置你希望的缩略图的宽度和高度。

            int srcWidth = image.Width;
            int srcHeight = image.Height;
            int thumbHeight = Convert.ToInt16((Convert.ToSingle(srcHeight) / Convert.ToSingle(srcWidth)) * Convert.ToSingle(thumbWidth));
            Bitmap bmp = new Bitmap(thumbWidth, thumbHeight);

            //从Bitmap创建一个System.Drawing.Graphics对象，用来绘制高质量的缩小图。

            System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);

            //设置 System.Drawing.Graphics对象的SmoothingMode属性为HighQuality

            gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //下面这个也设成高质量

            gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;

            //下面这个设成High

            gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //把原始图像绘制成上面所设置宽高的缩小图

            System.Drawing.Rectangle rectDestination = new System.Drawing.Rectangle(0, 0, thumbWidth, thumbHeight);
            gr.DrawImage(image, rectDestination, 0, 0, srcWidth, srcHeight, GraphicsUnit.Pixel);

            //保存图像，大功告成！

            bmp.Save(dest);

            //最后别忘了释放资源
            bmp.Dispose();
            image.Dispose();
        }