asp.net生成高清晰缩略图

#region 图像处理  
    /// <summary>   
    /// 生成缩略图   
    /// </summary>   
    /// <param name="M_OriginalImagePath">源图路径（物理路径）</param>   
    /// <param name="M_ThumbnailPath">缩略图路径（物理路径）</param>   
    /// <param name="M_Width">缩略图宽度</param>   
    /// <param name="M_Height">缩略图高度</param>     
    public static  void MakeThumbnail(string M_OriginalImagePath, string M_ThumbnailPath, int M_Width, int M_Height)  
    {  
        System.Drawing.Image originalImage = System.Drawing.Image.FromFile(M_OriginalImagePath);  
        int towidth = 0;  
        int toheight = 0;  
        if (originalImage.Width >= M_Width && originalImage.Height <= M_Height)  
        {  
            towidth = M_Width;  
            toheight = originalImage.Height;  
        }  
        if (originalImage.Width <= M_Width && originalImage.Height >= M_Height)  
        {  
            towidth = originalImage.Width;  
            toheight = M_Height;  
        }  
        if (originalImage.Width >= M_Width && originalImage.Height >= M_Height)  
        {  
            towidth = M_Width;  
            toheight = M_Height;  
        }  
        if (originalImage.Width <= M_Width && originalImage.Height <= M_Height)  
        {  
            towidth = originalImage.Width;  
            toheight = originalImage.Height;  
        }  
        int x = 0;//左上角的x坐标   
        int y = 0;//左上角的y坐标   
         //新建一个bmp图片   
        System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);  
        //新建一个画板   
        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;  
        //清空画布并以透明背景色填充   
        g.Clear(Color.Transparent);  
        //在指定位置并且按指定大小绘制原图片的指定部分   
        g.DrawImage(originalImage, x, y, towidth, toheight);  
        try 
        {  
            //以jpg格式保存缩略图   
            bitmap.Save(M_ThumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);  
        }  
        catch (System.Exception e)  
        {  
            throw e;  
        }  
        finally 
        {  
            originalImage.Dispose();  
            bitmap.Dispose();  
            g.Dispose();  
        }  
    } 
    #endregion 

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/wangjun8868/archive/2008/11/12/3283493.aspx