function 
GetNumColors: LongInt;
var
   
BPP: Integer;
   DC: HDC;
begin
   
DC := CreateDC('DISPLAY'
, nil
, nil
, nil
);
   if 
DC <> 0 then begin
      try
	 
BPP := GetDeviceCaps(DC, BITPIXEL) * GetDeviceCaps(DC, PLANES);
      finally
         
DeleteDC(DC);
      end
;
      case 
BPP of
         
1: Result := 2;
         4: Result := 16;
         8: Result := 256;
         15: Result := 32768;
         16: Result := 65536;
         24: Result := 16777216;
      end
;
   end else
      
Result := 0;
end
;