Private Sub cmdGo_Click()
Dim clr As Long
Dim r As Integer
Dim g As Integer
Dim b As Integer
Dim X As Integer
Dim Y As Integer
Dim fraction As Single

    cmdGo.Enabled = False
    MousePointer = vbHourglass
    DoEvents

    fraction = CSng(txtBrightness)

    picTo.AutoRedraw = True
    picTo.Width = picFrom.Width
    picTo.Height = picFrom.Height
    picTo.ScaleMode = vbPixels
    picFrom.ScaleMode = vbPixels

    For Y = 0 To picFrom.ScaleHeight
        For X = 0 To picFrom.ScaleWidth
            ' Get the source pixel's color components.
            clr = picFrom.Point(X, Y)
            r = clr Mod 256
            g = (clr \ 256) Mod 256
            b = clr \ 256 \ 256

            ' Decrease the brightness.
            r = r * fraction
            g = g * fraction
            b = b * fraction

            ' Write the new pixel.
            picTo.PSet (X, Y), RGB(r, g, b)
        Next X
        DoEvents
    Next Y

    ' Make the changes permanent.
    picTo.Picture = picTo.Image

    cmdGo.Enabled = True
    MousePointer = vbDefault
End Sub