Private Function Thumbnail_Proportional(ByVal b As Bitmap, ByVal w As _
  Integer, ByVal h As Integer) As Bitmap
    			If w = 0 And h = 0 Then
      				w = b.Size.Width
      				h = b.Size.Height
    			ElseIf w = 0 Then
      				w = CInt(h / b.Size.Height * b.Size.Width)
    			ElseIf h = 0 Then
      				h = CInt(w / b.Size.Width * b.Size.Height)
    			End If
    			Return CType(b.GetThumbnailImage(w, h, Nothing, IntPtr.Zero), Bitmap)
  		End Function
 
 
		Private Sub Cmd_grafikvorschau1Click(sender As System.Object, e As _
  System.EventArgs)
			Dim x, y As Integer
    		Dim sPath As String = Durchsuchen()
    			If sPath <> String.Empty Then
      				Dim b As Bitmap = New Bitmap(sPath)
      				Pcb_grafikvorschau1.Image = b
      				Dim ThumbnailProp As Bitmap = Thumbnail_Proportional(b, 50, 0)
      				Pcb_grafikvorschau2.Image = ThumbnailProp
    			End If
		End Sub
 
		Private Function Durchsuchen() As String
    		Dim OpenFileDialog1 As New OpenFileDialog
    			With OpenFileDialog1
      				Dim sb As New System.Text.StringBuilder
      				With sb
        				.Append("*.bmp,*.gif,*.jpg,*.png,*.wmf,*.emf,*.ico")
				        .Append("|*.bmp")
				        .Append(";*.gif")
				        .Append(";*.jpg")
				        .Append(";*.png")
				        .Append(";*.wmf")
				        .Append(";*.emf")
				        .Append(";*.ico")
      				End With
      				.Filter = sb.ToString
      				.FilterIndex = 1
      				.RestoreDirectory = True
      				If .ShowDialog() = DialogResult.OK Then
        				Return .FileName
      				End If
    			End With
  		End Function
 
		Private Sub Cmd_grafikvorschau2Click(sender As System.Object, e As _
  System.EventArgs)
				pcb_grafikvorschau1.Image = Nothing
				pcb_grafikvorschau2.Image = Nothing
		End Sub