Black·silver·yellow: Niessen & De Vries decided to use only 3 colours for the sake of clarity: black, silver and yellow. The consequent use of these three colours (in stead of for example full-colour images) results in an easily recognizable image appropriate for the visually impaired. Moreover, the combination of black letters on a yellow background is the easiest to read. The second easiest is the combination of grey (silver) letters on a white background.