Private Sub bild()
 
        Dim fs As IO.FileStream
        Dim bw As IO.BinaryWriter
        Dim bufferSize As Integer = 100
        Dim outbyte(bufferSize - 1) As Byte
        Dim retval As Long
        Dim startIndex As Long = 0
        Dim myreader As OracleClient.OracleDataReader
        Dim reader As Int32
 
        OC_bild.Connection = prnt.MyConnection
        OC_bild.CommandText = "select bild from befund where befund_id = '" & _
          txt_Befund_ID.Text & "'"
        myreader = OC_bild.ExecuteReader(CommandBehavior.SequentialAccess)
        OC_bild.CommandText = "select befund_id from befund where bild is not" & _
          "null and befund_id = '" & txt_Befund_ID.Text & "'"
        reader = OC_bild.ExecuteScalar
 
        If reader = txt_Befund_ID.Text Then
            If IO.File.Exists("bild.jpg") = True Then
                IO.File.Delete("bild.jpg")
            End If
            Do While myreader.Read()
 
                fs = New IO.FileStream("bild.jpg", IO.FileMode.OpenOrCreate, _
                  IO.FileAccess.Write)
                bw = New IO.BinaryWriter(fs)
                startIndex = 0
                retval = myreader.GetBytes(0, startIndex, outbyte, 0, _
                  bufferSize)
 
                Do While retval = bufferSize
                    bw.Write(outbyte)
                    bw.Flush()
                    startIndex += bufferSize
                    retval = myreader.GetBytes(0, startIndex, outbyte, 0, _
                      bufferSize)
                Loop
 
                bw.Write(outbyte, 0, retval - 1)
                bw.Flush()
 
                bw.Close()
                fs.Close()
            Loop
            myreader.Close()
            Dim img As Image = Image.FromFile("bild.jpg")
            Dim bild As Image
            Dim maxwidth, maxheight As Integer
            Dim callback As System.Drawing.Image.GetThumbnailImageAbort
            maxwidth = 256
            maxheight = 184
            bild = CalculateThumbnailSize(img, maxwidth, maxheight)
            PB_bild.SizeMode = PictureBoxSizeMode.CenterImage
            PB_bild.Image = bild
            PB_bild.Refresh()
            img.Dispose()
            bild.Dispose()
        Else
            PB_bild.Image = Image.FromFile("na.gif")
            PB_bild.Refresh()
        End If
 
    End Sub

Private Function CalculateThumbnailSize(ByRef Img As Image, ByVal MaxWidth As _
  Integer, ByVal MaxHeight As Integer) As Image
        Static tWidth As Integer, tHeight As Integer
        Dim Ratio As Single
        Dim I As Single
        Dim bild As Image
        If Img Is Nothing Then Exit Function
        If Img.Width / MaxWidth > Img.Height / MaxHeight Then
            If tWidth <> 96 Then
                Ratio = Img.Width / Img.Height
                tWidth = Img.Width / (Img.Width / MaxWidth)
                tHeight = tWidth / Ratio
            End If
        Else
            If tHeight <> 96 Then
                Ratio = Img.Height / Img.Width
                tHeight = Img.Height / (Img.Height / MaxHeight)
                tWidth = tHeight / Ratio
            End If
        End If
        bild = Img.GetThumbnailImage(tWidth, tHeight, Nothing, Nothing)
        Return bild
    End Function