Question about TIFF Viewer Demo sample

'LOAD THUMBNAIL
Private Sub loadThumbnailJpeg(ByVal fileName As String)
            filename="C:\test.jpg"
            jpegReader = New JpegReader(fileName)

            imageList.ImageSize = New Size(200, 200)
            imageList.ColorDepth = ColorDepth.Depth24Bit
            thumbnailsView.LargeImageList = imageList

            For Each frame As JpegFrame In jpegReader
                Dim thumbnailBitmap As New Aurigma.GraphicsMill.Bitmap
                frame.GetThumbnail(thumbnailBitmap, 200, 200)
                Dim thumbnail As Aurigma.GraphicsMill.Bitmap = CreateThumbnail(thumbnailBitmap)'<---CREATE THUMBNAIL
                thumbnailsView.Items.Add("Page " & (number + 1).ToString(), number)            
                imageList.Images.Add(thumbnail.ToGdiplusBitmap())
                number += 1
                jpegReader.Close()
                frame.Dispose()
                thumbnail.Dispose()
            Next
End Sub

'THUMBNAIL CREATION
Private Function CreateThumbnail(ByVal source As Aurigma.GraphicsMill.Bitmap) As Aurigma.GraphicsMill.Bitmap
            '1.CREATION OF THE WHITE(EMPTY) BITMAP(THUMBNAIL)
            Dim thumbnailBitmap As New Aurigma.GraphicsMill.Bitmap(Aurigma.GraphicsMill.RgbColor.White, 200, 200, PixelFormat.Format24bppRgb)          

            '2.PUT THE IMAGE ONTO THE BITMAP(THUMBNAIL)
            source.Draw(thumbnailBitmap, New Rectangle(CInt(CSng(thumbnailBitmap.Width - source.Width) / 2), _
               CInt(CSng(thumbnailBitmap.Height - source.Height) / 2), source.Width, source.Height), _
               CombineMode.Alpha, 1, InterpolationMode.LowQuality)

            '3.CREATION OF THE BLACK PERIMETER ON THE THUMBNAIL
            Dim graphics As GdiGraphics = thumbnailBitmap.GetGdiGraphics()
            Dim pen As New Aurigma.GraphicsMill.Drawing.Pen(RgbColor.Black, 1)
            graphics.DrawRectangle(pen, CInt((thumbnailBitmap.Width - source.Width) / 2), _
             CInt((thumbnailBitmap.Height - source.Height) / 2), source.Width - 2, source.Height - 2)
            graphics.Dispose()
           
            Return thumbnailBitmap       
End Function

'THIS IS HOW WE SHOW EACH THUMBNAIL, WHEN WE CLICK WITH MOUSE ON IT
Private Sub thumbnailsView_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles thumbnailsView.SelectedIndexChanged
        Dim filename, extension As String
        Dim selectedThumbnailIndex As Integer     
        Dim frame
     
            If thumbnailsView.SelectedIndices.Count > 0 Then
                selectedThumbnailIndex = thumbnailsView.SelectedIndices(0)                             
                filename = "c:\TEST.JPG"
                extension = IO.Path.GetExtension(filename)
                If extension = ".jpg" Then 
                        jpegReader = New JpegReader(filename) 
                        frame = New JpegFrame
                        frame = CType(jpegReader.LoadFrame(0), JpegFrame)
                    End If
                frame.GetBitmap(bitmapViewerMainView.Bitmap)             
                frame.Dispose()             
            End If        
End Sub