vb.net mirror an image

Public Class Form1
    Dim bitmap1 As Bitmap
    Private Sub btnInput_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnInput.Click
        Try
            OpenFileDialog1.ShowDialog()
            Label2.Visible = False
            Label2.Text = Nothing
            Dim fs As IO.FileStream = New IO.FileStream(OpenFileDialog1.FileName, IO.FileMode.Open)
            bitmap1 = Image.FromStream(fs)
            fs.Close()
            PictureBox1.Image = bitmap1
            Dim bmts As New Bitmap(bitmap1.Width, bitmap1.Height)
            For W = 1 To bitmap1.Width - 1
                For H = 1 To bitmap1.Height - 1
                    bmts.SetPixel(W, H, bitmap1.GetPixel(bitmap1.Width - W, H))
                Next
            Next
            PictureBox2.Image = bmts
        Catch ex As Exception
            MsgBox("select an input path picture file")
        End Try
    End Sub
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        OpenFileDialog1.FileName = Nothing
        SaveFileDialog1.FileName = Nothing
        SaveFileDialog1.Filter = "JPeg Image|*.jpg|Bitmap Image|*.bmp"
    End Sub
    Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
        Try
            SaveFileDialog1.ShowDialog()
            Label1.Text = SaveFileDialog1.FileName
            Dim bmts As New Bitmap(PictureBox2.Image)
            Dim bitmapToSave As New Bitmap(bmts)
            bitmapToSave.Save(SaveFileDialog1.FileName, Imaging.ImageFormat.Bmp)
            Label2.Text = "image mirroring completed"
            Label2.Visible = True
        Catch ex As Exception
            MsgBox("error")
        End Try
    End Sub
End Class