String bitmapFile = String.Empty;
            String newBitmapFile = String.Empty;
            var openf = new OpenFileDialog();
            openf.Filter = "png|*.png|jpg|*.jpg|ico|*.ico";
            if (openf.ShowDialog() == DialogResult.OK) {
                bitmapFile = openf.FileName;
                newBitmapFile = bitmapFile.Substring(0, bitmapFile.LastIndexOf('\\')) + @"\" + "abc.png";
            }
            Thread th1 = new Thread(
                () => {
                    try {
                        Bitmap bitmap = new Bitmap(bitmapFile);
                        Graphics gp = Graphics.FromImage(bitmap);
                        String label = "LY製作";
                        Font font = new Font("KaiTi",bitmap.Width/10,FontStyle.Bold);
                        SolidBrush sbrush = new SolidBrush(Color.Red);
                        int x = bitmap.Width / 2;
                        int y = bitmap.Height / 2;
                        gp.DrawString(label,font,sbrush,x,y);
                        bitmap.Save(newBitmapFile);
                    }
                    catch (Exception ee) {

                    }
                    finally {

                    }
                }
                );
            th1.Start();
 

黑體：SimHei 
宋體：SimSun 
新宋體：NSimSun 
仿宋：FangSong 
楷體：KaiTi 
仿宋_GB2312：FangSong_GB2312 
楷體_GB2312：KaiTi_GB2312 
微軟雅黑體：Microsoft YaHei