C # Get Image Image format

Private voidButton1_click_1 (Objectsender, EventArgs e) {            stringPath =Application.startuppath; using(FileStream file =NewFileStream (Txtpath. Text, FileMode.Open)) {Image img=image.fromstream (file); stringformat; System.Drawing.Imaging.ImageFormat _img_format= Getimageformat (IMG, outformat); if(_img_format! =NULL) {img. Save (Path+@"\"+ Guid.NewGuid (). ToString () +format, _img_format); MessageBox.Show ("OK"); }            }                    }        /// <summary>        ///Get image Image format/// </summary>        /// <param name= "file" ></param>        /// <param name= "format" ></param>        /// <returns></returns>        PrivateSystem.Drawing.Imaging.ImageFormat Getimageformat (FileStream file, out stringformat) {            byte[] sb =New byte[2];//This reads the position length of the direct 0-1.File. Read (SB,0, sb.            Length); //Judging by the file header            stringStrflag = sb[0]. ToString () + sb[1].            ToString (); //View format Type            Switch(strflag) {//jpg format                 Case"255216": Format=". jpg"; returnSystem.Drawing.Imaging.ImageFormat.Jpeg; //gif format                 Case"7173": Format=". gif"; returnSystem.Drawing.Imaging.ImageFormat.Gif; //BMP Format                 Case"6677": Format=". bmp"; returnSystem.Drawing.Imaging.ImageFormat.Bmp; //PNG format                 Case"13780": Format=". PNG"; returnSystem.Drawing.Imaging.ImageFormat.Png; //Other formats                default: Format=string.                    Empty; return NULL; }        }        /// <summary>        ///Get image Image format/// </summary>        /// <param name= "_img" ></param>        /// <param name= "format" ></param>        /// <returns></returns>        PrivateSystem.Drawing.Imaging.ImageFormat Getimageformat (Image _img, out stringformat) {            if(_img. Rawformat.equals (System.Drawing.Imaging.ImageFormat.Jpeg)) {format=". jpg"; returnSystem.Drawing.Imaging.ImageFormat.Jpeg; }            if(_img. Rawformat.equals (System.Drawing.Imaging.ImageFormat.Gif)) {format=". gif"; returnSystem.Drawing.Imaging.ImageFormat.Gif; }            if(_img. Rawformat.equals (System.Drawing.Imaging.ImageFormat.Png)) {format=". PNG"; returnSystem.Drawing.Imaging.ImageFormat.Png; }            if(_img. Rawformat.equals (SYSTEM.DRAWING.IMAGING.IMAGEFORMAT.BMP)) {format=". bmp"; returnSystem.Drawing.Imaging.ImageFormat.Bmp; } format=string.            Empty; return NULL; }

C # Get Image Image format