Public Class frmTestPicBox
 
    Dim pb As New PictureBox With 
        {.Parent = Me, .SizeMode = PictureBoxSizeMode.Zoom,
        .Location = New Point(10, 10), .Size = New Drawing.Size(592, 333)}
 
    Dim bmp As New Bitmap(2640, 1485)
 
 
    Private Sub frmTestPicBox_Load(sender As Object, 
        e As EventArgs) Handles MyBase.Load
 
        Me.Size = New Size(600, 400)
        Me.BackColor = Color.Yellow
        pb.BackColor = Color.Red
 
        Using g As Graphics = Graphics.FromImage(bmp)
            g.Clear(Color.Green)
        End Using
 
        pb.Image = bmp
 
    End Sub
End Class

Public Class frmTestPicBox
 
    Dim pb As New PictureBox With {.Parent = Me, .SizeMode = _
      PictureBoxSizeMode.Zoom,
        .Location = New Point(10, 10), .Size = New Drawing.Size(592, 333), 
        .BorderStyle = BorderStyle.None}
 
    Dim bmp As New Bitmap(2640, 1485)
 
 
    Private Sub frmTestPicBox_Load(sender As Object, 
        e As EventArgs) Handles MyBase.Load
 
        Me.Size = New Size(600, 400)
        Me.BackColor = Color.Yellow
        pb.BackColor = Color.Red
 
        Dim bmp_out As New Bitmap(pb.Width, pb.Height)
        Using g As Graphics = System.Drawing.Graphics.FromImage(bmp_out)
            g.DrawImage(bmp, New Rectangle(0, 0, bmp_out.Width, bmp_out.Height))
        End Using
 
        pb.Image = bmp_out
    End Sub
 
 
End Class

    Public Class frmTestPicBox
 
    Dim pb As New PictureBox With 
        {.Parent = Me, .SizeMode = PictureBoxSizeMode.Zoom,
        .Location = New Point(10, 10), .Size = New Drawing.Size(592, 333)}
 
    ' --> gleiche Seitenverhältnisse, aber... 
    ' Dim bmp As New Bitmap(2640, 1485)
      ' 2640:592=4.4594594... 2640:1485=1.77777...  --> mit Randstreifen
 
    Dim bmp As New Bitmap(2720, 1530)
      ' 2720:592=4.5944594... 2720:1530=1.77777...  --> o h n e Randstreifen
 
 
    Private Sub frmTestPicBox_Load 
       (sender As Object, e As EventArgs) Handles MyBase.Load
 
        Me.Size = New Size(628, 392)
        Me.BackColor = Color.Yellow
        pb.BackColor = Color.Red
 
        Using g As Graphics = Graphics.FromImage(bmp)
            g.Clear(Color.Green)
        End Using
 
        pb.Image = bmp
    End Sub
End Class

  Private Sub Rotate()
  Dim relPicIn, RelPic2 As Decimal
  Dim inW_half, inH_half As Decimal 
  Dim rotW_half, rotH_half, rotL, rotT As Decimal
  Dim theta As Double =  HScrollBar1.Value * PI / 180.0
    If theta < 0 Then theta *= -1 theta * -1
  Dim sin_theta As Double = Sin(theta)
  Dim cos_theta As Double = Cos(theta)
  inW_half = CDec(bmp_In.Width/2)
  inH_half = CDec(bmp_In.Height/2)
  rotW_half = CDec(Math.Floor(inW_half*cos_theta+inH_half*sin_theta))
  rotH_half = CDec(Math.Floor(inW_half*sin_theta+inH_half*cos_theta))
  rotL = CDec(rotW_half-inW_half*cos_theta+inH_half*sin_theta)
  rotT = CDec(rotH_half-(-inW_half*sin_theta+inH_half*cos_theta))
  bmp_Out = New Bitmap(CInt(2*rotW_half), CInt(2*rotH_half))
  Dim g As Drawing.Graphics = Graphics.FromImage(bmp_Out)
    g.Clear(Color.LightGray)
    Dim p_center As PointF
    p_center.X = rotW_half
    p_center.Y = rotH_half
    Dim m As New Drawing.Drawing2D.Matrix
      m.RotateAt(HScrollBar1.Value, p_center)
      g.Transform = m 
      Dim source_rect As New Rectangle(0, 0, bmp_In.Width, bmp_In.Height)
      Dim intX As Integer = CInt((bmp_Out.Width-bmp_In.Width)/2)
      Dim intY As Integer = CInt((bmp_Out.Height-bmp_In.Height)/2)
      Dim dest_rect As New Rectangle(intX,intY,bmp_In.Width,bmp_In.Height)
      g.DrawImage(bmp_In, dest_rect, source_rect, GraphicsUnit.Pixel)
    m.Dispose()
  g.Dispose()
  pb1.Image = bmp_Out
  RelPic2 = rotT/(2*rotW_half-rotL) 
  relPicIn = CDec(bmp_In.Height/bmp_In.Width)
   If relPicIn < 1 Then
    If relPicIn = pb1.Height/pb1.Width Then 
      out_rect.Width = CInt(Math.Floor(2*(rotH_half-rotT+rotW_half*RelPic2)/( _
        relPicIn+RelPic2)/16)*16)
    Else
      out_rect.Width = CInt(Math.Floor(2*(rotH_half-rotT+rotW_half*RelPic2)/( _
        relPicIn+RelPic2)))
    End                             |
    out_rect.Height = CInt(Math.Floor(out_rect.Width*relPicIn))
  Else
    out_rect.Height = CInt((2*(rotW_half-rotL+rotH_half*RelPic2)/( _
      bmp_In.Width/bmp_In.Height+RelPic2)))
    out_rect.Width = CInt((out_rect.Height/relPicIn))
  End If 
  out_rect.X = CInt(rotW_half-out_rect.Width/2)
  out_rect.y =  CInt(rotH_half-out_rect.Height/2)
  If bmp_Out.Height/bmp_Out.Width > pb1.Height/pb1.Width Then
    decZoom = CDec(bmp_Out.Height/pb1.Height)
  Else
    decZoom = CDec(bmp_Out.Width/pb1.Width)
  End If  
  If pb1.SizeMode = PictureBoxSizeMode.CenterImage Then decZoom = 1
  Dim ImagePart As Bitmap = New Bitmap(out_rect.Width, out_rect.Height)
  g = Graphics.FromImage(ImagePart)
    Dim TargetRect As Rectangle = New Rectangle(0, 0, out_rect.Width, _
      out_rect.Height)
    g.DrawImage(bmp_Out, TargetRect, out_rect, GraphicsUnit.Pixel)
  g.Dispose
  g = Nothing
  pb2.Image = ImagePart         
  If chbVollbild.Checked = True Then pb1.Image = ImagePart
  End Sub

Class MeinePictureBox
  Inherits PictureBox
 
  Protected Overrides Sub OnPaint(pe As PaintEventArgs)
    If Image IsNot Nothing AndAlso SizeMode = PictureBoxSizeMode.Zoom Then
      pe.Graphics.DrawImage(Image, ImageRectangle)
    Else
      MyBase.OnPaint(pe)
    End If
  End Sub
 
  Private Function ImageRectangle() As Rectangle
    Dim cr = ClientRectangle
    If Image IsNot Nothing Then
      Dim ims = Image.Size
      Dim ratio = Math.Min(cr.Width / ims.Width, cr.Height / ims.Height)
      cr.Width = CInt(ims.Width * ratio)
      cr.Height = CInt(ims.Height * ratio)
      cr.X = (Me.Width - cr.Width) \ 2
      cr.Y = (Me.Height - cr.Height) \ 2
    End If
    Return cr
  End Function
 
End Class

  Protected Overrides Sub OnPaint(pe As PaintEventArgs)
    If Image IsNot Nothing AndAlso SizeMode = PictureBoxSizeMode.Zoom Then
      Dim g = pe.Graphics
      'Verschieben zum Mittelpunkt
      g.TranslateTransform(Me.Width / 2.0F, Me.Height / 2.0F)
      'Drehen um 5 Grad
      g.RotateTransform(5.0F)
      'Grafik vergrößern, damit keine Ränder sichtbar sind
      '(der genaue Faktor muss berechnet werden!)
      g.ScaleTransform(1.2F, 1.2F)
      'Zurückverschieben
      g.TranslateTransform(-Me.Width / 2.0F, -Me.Height / 2.0F)
      'Qualität verbessern
      g.InterpolationMode = Drawing2D.InterpolationMode.HighQualityBicubic
      'Bild zeichnen
      g.DrawImage(Image, ImageRectangle)
    Else
      MyBase.OnPaint(pe) 'internes zeichnen
    End If
  End Sub

Private Sub myPb1_Paint _
  (sender As Object, e As System.Windows.Forms.PaintEventArgs) Handles pb1.Paint
 
If out_rect.Width = 0 Then Exit Sub ' nach Load -> Exit Sub
 
Dim pbRectOut As Rectangle     
 
'*** Ausgabe-Rechteck 
' **************************************************************
  pbRectOut.X = CInt((myPb1.Width - out_rect.Width / decZoom) / 2) 
  pbRectOut.Y = CInt((myPb1.Height - out_rect.Height / decZoom) / 2
  pbRectOut.Width = CInt(out_rect.Width / decZoom
  pbRectOut.Height = CInt(out_rect.Height / decZoom
 
  If chbVollbild.Checked = False And HScrollBar1.Value <> 0 Then
    e.Graphics.DrawRectangle(Pens.White, pbRectOut)
  End If
 
'*** Diagonalen 
' ********************************************************************
  If chbDiagonalen.Checked = True And HScrollBar1.Value <> 0 And _
    chbVollbild.Checked = False Then
    Dim PenDiag As Pen = New Pen(Color.White)
    PenDiag.DashStyle = DashStyle.DashDotDot
    Dim pntD(3) As Point
 
    pntD(0).X = CInt((myPb1.Width - bmp_In.Width / decZoom) / 2)
    pntD(0).Y = CInt((myPb1.Height - bmp_In.Height / decZoom) / 2)
    pntD(1).X = CInt(pntD(0).X + bmp_In.Width / decZoom)
    pntD(1).Y = pntD(0).Y
    pntD(2).X = pntD(0).X
    pntD(2).Y = CInt(pntD(0).Y + bmp_In.Height / decZoom)
    pntD(3).X = pntD(1).X
    pntD(3).Y = pntD(2).Y
    e.Graphics.DrawLine(PenDiag, pntD(0), pntD(3))
    e.Graphics.DrawLine(PenDiag, pntD(1), pntD(2))
 
    e.Graphics.DrawLine(PenDiag, pntD(0), pntD(1))
    e.Graphics.DrawLine(PenDiag, pntD(1), pntD(3))
    e.Graphics.DrawLine(PenDiag, pntD(3), pntD(2))
    e.Graphics.DrawLine(PenDiag, pntD(2), pntD(0))
  End If
 
'*** Raster 
' ************************************************************************
  If chbRaster.Checked = True Then
    . . .
  End If
  End Sub

Protected Overrides Sub OnPaint(pe As PaintEventArgs)
  If Image IsNot Nothing AndAlso SizeMode = PictureBoxSizeMode.Zoom Then
    pe.Graphics.DrawImage(Image, ImageRectangle)
  End If
  MyBase.OnPaint(pe)
End Sub

  Shadows Event Paint As PaintEventHandler
 
  Protected Overrides Sub OnPaint(pe As PaintEventArgs)
    If Image IsNot Nothing AndAlso SizeMode = PictureBoxSizeMode.Zoom Then
      pe.Graphics.DrawImage(Image, ImageRectangle)
    Else
      MyBase.OnPaint(pe)
    End If
    RaiseEvent Paint(Me, pe)
  End Sub

Dim s As Single = 23.7F
Dim i As Integer = CInt(s) ' = 24

float s = 23.7f;
int i = (int)s; // = 23