Validate Image Type Using Image GUID in ASP.NET

http://www.codeproject.com/Tips/409328/Validate-Image-Type-Using-Image-GUID-in-ASP-NET

System.Drawing.Image image = System.Drawing.Image.FromStream(FileUpload1.FileContent);
        string FormetType = string.Empty;
        if (image.RawFormat.Guid == System.Drawing.Imaging.ImageFormat.Tiff.Guid)
            FormetType = "TIFF";
        else if (image.RawFormat.Guid == System.Drawing.Imaging.ImageFormat.Gif.Guid)
            FormetType = "GIF";
        else if (image.RawFormat.Guid == System.Drawing.Imaging.ImageFormat.Jpeg.Guid)
            FormetType = "JPG";
        else if (image.RawFormat.Guid == System.Drawing.Imaging.ImageFormat.Bmp.Guid)
            FormetType = "BMP";
        else if (image.RawFormat.Guid == System.Drawing.Imaging.ImageFormat.Png.Guid)
            FormetType = "PNG";
        else if (image.RawFormat.Guid == System.Drawing.Imaging.ImageFormat.Icon.Guid)
            FormetType = "ICO";
        else