我画完了一张Graphics 的图片之后，应该怎么样把它保存！
希望回答具体点（本人是超级菜鸟），谢谢

string fname = "";
            SaveFileDialog sf = new SaveFileDialog();

            sf.Filter = "JPG文件(*.jpg)|*.jpg|BMP文件(*.bmp)|*.bmp";
            sf.FilterIndex = 1;

            if (sf.ShowDialog() == DialogResult.OK)
            {
                fname = sf.FileName;
                if (fname != "")
                {
                    this.DrawpictureBox.Image.Save(fname, ImageFormat.Gif);
                }

            }
            sf.Dispose();