The task is to display a series of vertical greyscale bars (contrast bars) with a sufficient number of bars to span the entire width of the display.

For the top quarter of the display, the left hand bar should be black, and we then incrementally step through six shades of grey until we have a white bar on the right hand side of the display. (This gives a total of 8 bars)

For the second quarter down, we start with white and step down through 14 shades of gray, getting darker until we have black on the right hand side of the display. (This gives a total of 16 bars).

Halfway down the display, we start with black, and produce 32 bars, ending in white, and for the last quarter, we start with white and step through 62 shades of grey, before finally arriving at black in the bottom right hand corner, producing a total of 64 bars for the bottom quarter.

Public Sub Form_Open()
Dim iRow, iCol, iClr As Integer                                     'For Row, Column and Colour
Dim iInc As Integer = 4                                             'To calculate RGB colour
Dim h1Panel As Panel                                                'Panels to display colours
 
With Me                                                             'Setup the Form
  .Arrangement = Arrange.Row                                        'Arrange children in rows
  .Border = False                                                   'No Border
  .Height = Desktop.Height                                          'Fill the screen
  .Width = Desktop.Width                                            'Fill the screen
  .Fullscreen = True                                                'Set the Form to Fullscreen
End With
 
For iRow = 1 To 4                                                   'For each row..
  iInc += iInc                                                      'Increase iInc by itself
  For iCol = 0 To iInc - 1                                          'For each column..
    iClr = iCol * (256 / iInc)                                      'Set the RGB colour
    If iRow = 2 Or iRow = 4 Then iClr = 255 - (iCol * (256 / iInc)) 'If row 2 or 4 then reverse the colours
    h1Panel = New Panel(Me)                                         'Create a new Panel
    With h1Panel                                                    'With the Panel..
      .Width = Desktop.Width / iInc                                 'Set the width
      .Height = Desktop.Height / 4                                  'Set the height
      .Background = Color.RGB(iClr, iClr, iClr)                     'Set the Background colour
      .Border = Border.Plain                                        'Set a Border (It's easier to see the colour changes)
    End With
  Next
Next
 
End