Private Sub pb_Paint(sender As Object, _
        e As System.Windows.Forms.PaintEventArgs) Handles pb.Paint
 
        Dim brt As Single = 0.2 'Helligkeit im Texthintergrund erhöhen
        Dim ctr As Single = 1.1 'Kontrast erhöhen
 
        Dim cm As Imaging.ColorMatrix = _
               New Imaging.ColorMatrix(New Single()() _
               {New Single() {ctr, 0.0, 0.0, 0.0, 0.0}, _
                New Single() {0.0, ctr, 0.0, 0.0, 0.0}, _
                New Single() {0.0, 0.0, ctr, 0.0, 0.0}, _
                New Single() {0.0, 0.0, 0.0, 1.0, 0.0}, _
                New Single() {brt, brt, brt, 0, 1.0}})
 
        Dim ia As New Imaging.ImageAttributes
        ia.SetColorMatrix(cm)
 
        Using br As New SolidBrush(tb.ForeColor)
            With e.Graphics
                'Texthintergrund zeichnen
                Dim rect As New RectangleF _
                       (textposition, .MeasureString(tb.Text, tb.Font, _
                       tb.Width))
                .DrawImage(bmp_picture, _
                       RectangleToPoints(rect), rect, GraphicsUnit.Pixel, ia)
 
                .DrawString(tb.Text, tb.Font, br, textposition)
            End With
 
        End Using
 
    End Sub
 
 
    Private Function RectangleToPoints(ByVal rect As RectangleF) As PointF()
        'Points-Parameter aus Rectangle berechnen
        Dim points(2) As PointF
        With rect
            points(0) = .Location
            points(1) = New PointF(.Location.X + .Width, .Location.Y)
            points(2) = New PointF(.Location.X, .Location.Y + .Height)
        End With
        Return points
    End Function