Validate Image Type Using Image GUID in ASP.NET

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing.Imaging;
public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void butSave_Click(object sender, EventArgs e)
    {
        try
        {
            if (FileUpload1.HasFile)
            {
                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
                    throw new System.ArgumentException("Invalid File Type");

                lblMessage.Text = "File Formet Is:" + FormetType;
            }
        }
        catch (System.ArgumentException exp)
        {
            lblMessage.Text="Invalid File";
        }
        catch (Exception ex)
        {
            lblMessage.Text = ex.Message;
            
        }

    }
}