Csharp: create Transparent Images in winform

//透明背景图           Brush b = new SolidBrush(Color.FromArgb(50, Color.Transparent));            Bitmap image = new Bitmap(1015, 637);           Graphics g = Graphics.FromImage(image);           g.Clear(Color.Transparent);           g.FillRectangle(b, 0, 0, 1015, 637);           //g.DrawRectangle(Pens.Plum, 0, 0, 299, 49);           //Font font = new Font("Alba Super", 20, FontStyle.Underline);           //g.DrawString("This is a test.", font, Brushes.Plum, 10, 0);           //System.Drawing.Image icon = System.Drawing.Image.FromFile(Server.MapPath("your.gif"));           //g.DrawImageUnscaled(icon, 240, 0);           //image.Save(Response.OutputStream, System.Drawing.Imaging.ImageFormat.Gif);           //SolidBrush:定义单色画笔。画笔用于填充图形形状，如矩形、椭圆、扇形、多边形和封闭路径。           //这个画笔为描绘阴影的画笔，呈灰色           float alpha = 0;           int m_alpha = Convert.ToInt32(256 * alpha);           SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(m_alpha, 0, 0, 0));           //从四个 ARGB 分量（alpha、红色、绿色和蓝色）值创建 Color 结构，这里设置透明度为153           //这个画笔为描绘正式文字的笔刷，呈白色           SolidBrush semiTransBrush = new SolidBrush(Color.FromArgb(153, 255, 255, 255));           g.DrawImage(image, 0, 0, image.Width, image.Height);           Font f = new Font(setFont, 18, FontStyle.Bold); //字體大小           Font fno = new Font(setFont, 10, FontStyle.Bold);           Font fclerk = new Font(setFont, 8, FontStyle.Bold);           Brush fb = new SolidBrush(Color.Black); //字體顏色                           string addText = "塗聚文";           //new RectangleF(0, 0, 500, 500), strFormat)             g.DrawString(addText, f, fb, new RectangleF(130, 220, 550, 110), new StringFormat());//放的姓名位置           g.DrawString("行政及人事管理人員", fclerk, fb, new RectangleF(130, 410, 550, 110), new StringFormat());//放職稱的位置           g.DrawString("行政及人力资源管理部", fno, fb, new RectangleF(130, 470, 550, 110), new StringFormat());//放部門名稱的位置           g.DrawString("L00094", fno, fb, new RectangleF(130, 540, 550, 110), new StringFormat()); //放員工編號的位置           int xPosOfWm;           int yPosOfWm;           int phWidth = image.Width;           int phHeight = image.Height;           Photopath = dirInfo + "2cun.jpg"; //2寸照片           System.Drawing.Image copyImage = System.Drawing.Image.FromFile(Photopath);           int wmWidth = copyImage.Width;           int wmHeight = copyImage.Height;           xPosOfWm = phWidth - wmWidth - 80;           yPosOfWm = 80;           StringFormat strFormat = new StringFormat();           g.DrawImage(copyImage, new Rectangle(xPosOfWm, yPosOfWm, wmWidth, wmHeight), 0, 0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);           // Make backColor transparent for myBitmap.           ImageAttributes imgAttribs = new ImageAttributes();           imgAttribs.SetColorKey(Color.FromArgb(255, 255, 255), Color.FromArgb(255, 255, 255));           Color backColor = Color.Transparent;           image.MakeTransparent(backColor);           //image = MakeTransparentGif(image, Color.Transparent);           // Draw the transparent bitmap to the screen.           //g.DrawImage(image, image.Width, 0, image.Width, image.Height);           this.pictureBox1.Image = image;           image.Save(dirInfo + @"geovindu_1011.jpg", ImageFormat.Jpeg);           g.Dispose();