缩略图上水印处理（可处理GIF格式）

    /**//// <summary>
    /// 在图片上增加文字水印
    /// </summary>
    /// <param name="Path">原服务器图片路径</param>
    /// <param name="Path_sy">生成的带文字水印的图片路径</param>
    protected void AddShuiYinWord(string Path, string Path_sy)
    {
        string addText = "测试水印";
        System.Drawing.Image image = System.Drawing.Image.FromFile(Path);
        System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
        g.DrawImage(image, 0, 0, image.Width, image.Height);
        System.Drawing.Font f = new System.Drawing.Font("Verdana", 16);
        System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Blue);

        g.DrawString(addText, f, b, 15, 15);
        g.Dispose();

        image.Save(Path_sy);
        image.Dispose();
    }

    /**//// <summary>
    /// 在图片上生成图片水印
    /// </summary>
    /// <param name="Path">原服务器图片路径</param>
    /// <param name="Path_syp">生成的带图片水印的图片路径</param>
    /// <param name="Path_sypf">水印图片路径</param>
    protected void AddShuiYinPic(string Path, string Path_syp, string Path_sypf)
    {
        System.Drawing.Image image = System.Drawing.Image.FromFile(Path);
        System.Drawing.Image copyImage = System.Drawing.Image.FromFile(Path_sypf);
        Bitmap newBitmap = new Bitmap(image.Width, image.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
        newBitmap.SetResolution(image.HorizontalResolution, image.VerticalResolution);
        Graphics g = Graphics.FromImage(newBitmap);
        g.SmoothingMode = SmoothingMode.AntiAlias;
        g.DrawImage(image, new Rectangle(0, 0, image.Width, image.Height), 0, 0, image.Width, image.Height, GraphicsUnit.Pixel);
        g.Dispose();
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        newBitmap.Save(ms, ImageFormat.Jpeg);
        //重新生成Image对象
        image = System.Drawing.Image.FromStream(ms);
        
        g = System.Drawing.Graphics.FromImage(image);
        g.DrawImage(copyImage, new System.Drawing.Rectangle(image.Width - copyImage.Width, image.Height - copyImage.Height, copyImage.Width, copyImage.Height), 0, 0, copyImage.Width,copyImage.Height, System.Drawing.GraphicsUnit.Pixel);
        g.Dispose();

        image.Save(Path_syp);
        image.Dispose();
    }