gif图片转换成jpg文件格式

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Linq;
using System.Windows.Forms;
using System.IO;
using System.Drawing.Imaging;

namespace GIFChangeJPG
{
    public partial class Frm_Main : Form
    {
        Bitmap bitmap;
        public Frm_Main（）
        {
            InitializeComponent（）;
        }

        private void buttonOpen_Click（object sender EventArgs e）
        {
            OpenFileDialog openFileDialog = new OpenFileDialog（）;
            openFileDialog.Filter = “*.gif|*.gif|*.jpg|*.jpg;“;
            openFileDialog.title = “打开ICO文件“;
            openFileDialog.Multiselect = false;
            if （openFileDialog.ShowDialog（） == DialogResult.OK）
            {
                if （bitmap != null）
                {
                    bitmap.Dispose（）;
                }
                string fileName = openFileDialog.FileName;
          

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2011-12-22 23:11  GIFChangeJPG\
     文件         926  2010-07-08 21:54  GIFChangeJPG.sln
     目录           0  2011-12-22 23:11  GIFChangeJPG\bin\
     目录           0  2011-12-22 23:13  GIFChangeJPG\bin\Debug\
     文件        4400  2010-07-13 00:56  GIFChangeJPG\Frm_Main.cs
     文件        7218  2010-07-09 02:46  GIFChangeJPG\Frm_Main.designer.cs
     文件        5814  2010-07-09 02:46  GIFChangeJPG\Frm_Main.resx
     文件        3839  2010-11-04 01:47  GIFChangeJPG\GIFChangeJPG.csproj
     目录           0  2011-12-22 23:11  GIFChangeJPG\obj\
     目录           0  2011-12-22 23:14  GIFChangeJPG\obj\Debug\
     文件        2236  2010-11-04 01:47  GIFChangeJPG\obj\Debug\GIFChangeJPG.csproj.FileListAbsolute.txt
     目录           0  2011-12-22 23:11  GIFChangeJPG\obj\Debug\TempPE\
     文件         496  2010-07-08 21:55  GIFChangeJPG\Program.cs
     目录           0  2011-12-22 23:11  GIFChangeJPG\Properties\
     文件        1356  2010-07-08 21:54  GIFChangeJPG\Properties\AssemblyInfo.cs
     文件        2874  2010-07-08 21:54  GIFChangeJPG\Properties\Resources.Designer.cs
     文件        5612  2010-07-08 21:54  GIFChangeJPG\Properties\Resources.resx
     文件        1097  2010-07-08 21:54  GIFChangeJPG\Properties\Settings.Designer.cs
     文件         249  2010-07-08 21:54  GIFChangeJPG\Properties\Settings.settings