Dim Farben(16777215) As Boolean
Dim x As Long, y As Long, col As Long
 
For x = 0 To 16777215
    Farben(x) = False
Next
 
For y = 0 To Picture1.Height - 1
    For x = 0 To Picture1.Width - 1
 
        col = GetPixel(Picture1.hdc, x, y)
        Farben(col) = True
    Next x
Next y
 
y = 0
For x = 0 To 16777215
    If Farben(x) = True Then y = y + 1
Next
 
MsgBox ("Es sind " & Format(y) & " Farben im Bild."