Draw a rectangle in graphics on a picturebox and save to bitmap and save as tif - vb.net

Question

I draw a rectangle on a picture and want to save the picture it does not keep me well. The rectangle looks smaller and in the wrong position.
Here is the code:
Public Class Form10
Dim G_RegistInfoPathSinglePage = "D:\0_0_1.TIF"
Dim SelectRect As Rectangle = New Rectangle()
Dim _pen As Pen = New Pen(Color.Purple, 4)
Dim _brush As SolidBrush = New SolidBrush(Color.Pink)
Dim _ControlPressed As Boolean = False
Private Sub Form1_KeyDown(sender As Object, e As KeyEventArgs) Handles MyBase.KeyDown
_ControlPressed = (e.Modifiers And Keys.Control) = Keys.Control
End Sub
Private Sub Form1_KeyUp(sender As Object, e As KeyEventArgs) Handles Me.KeyUp
_ControlPressed = (e.Modifiers And Keys.Control) = Keys.Control
End Sub
Private Sub PictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles picOriginal.MouseDown
SelectRect.Location = e.Location
SelectRect.Size = New Size(0, 0)
End Sub
Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles picOriginal.MouseMove
If (e.Button = MouseButtons.Left) Then
ControlPaint.DrawReversibleFrame(picOriginal.RectangleToScreen(SelectRect), picOriginal.BackColor, FrameStyle.Dashed)
SelectRect.Width = e.X - SelectRect.X
SelectRect.Height = e.Y - SelectRect.Y
ControlPaint.DrawReversibleFrame(picOriginal.RectangleToScreen(SelectRect), picOriginal.BackColor, FrameStyle.Dashed)
End If
End Sub
Private Sub PictureBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles picOriginal.MouseUp
If (e.Y < SelectRect.Y) Then
SelectRect.Location = If(SelectRect.Location.X > e.X,
New Point(e.X, e.Y), New Point(SelectRect.X, e.Y))
SelectRect.Size = New Size(Math.Abs(SelectRect.Width), Math.Abs(SelectRect.Height))
Else
If SelectRect.Location.X > SelectRect.Right Then
SelectRect.Location = New Point(e.X, SelectRect.Y)
SelectRect.Size = New Size(Math.Abs(SelectRect.Width), Math.Abs(SelectRect.Height))
End If
End If
If _ControlPressed Then
Dim _InflatedRect As Rectangle = New Rectangle(SelectRect.Location, SelectRect.Size)
_InflatedRect.Inflate(CInt(_pen.Width / 2), CInt(_pen.Width / 2))
picOriginal.Invalidate(_InflatedRect)
Else
picOriginal.Invalidate()
End If
End Sub
'paint rectangle
Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles picOriginal.Paint
e.Graphics.DrawRectangle(_pen, SelectRect)
SelectRect.Inflate(CInt(-_pen.Width / 2), CInt(-_pen.Width / 2))
e.Graphics.FillRectangle(_brush, SelectRect)
End Sub
'if Pressing ctrl + S switches to a function that saves the image
Private Sub main_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyDown
If (e.KeyCode = Keys.S AndAlso e.Modifiers = Keys.Control) Then
SaveDrawRectengle()
MsgBox("Save successfully")
End If
End Sub
'save to image as tif
Public Sub SaveDrawRectengle()
Dim l_OriginalImage As New System.IO.FileStream(G_RegistInfoPathSinglePage, IO.FileMode.Open, IO.FileAccess.Read)
Dim OriginalImage = System.Drawing.Image.FromStream(l_OriginalImage)
Dim Bfr As Bitmap = New Bitmap(OriginalImage)
picOriginal.BackgroundImage = Bfr
Dim _image = picOriginal.BackgroundImage
Dim overlay As New Bitmap(_image.Width, _image.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb)
Dim g As Graphics = Graphics.FromImage(overlay)
g.DrawRectangle(_pen, SelectRect)
SelectRect.Inflate(CInt(-_pen.Width / 2), CInt(-_pen.Width / 2))
g.FillRectangle(_brush, SelectRect)
g.Dispose()
picOriginal.Image = overlay
l_OriginalImage.Close()
Dim Tmpimg As Image = New Bitmap(300, 100)
Tmpimg = CType(Bfr, Image)
Dim Tmpg As Graphics = Graphics.FromImage(Tmpimg)
Tmpg.DrawImage(CType(overlay, Image), New Point(10, 10))
Tmpimg.Save("D:\852.tif")
End Sub
End Class