A method of generating one image dot from three image pixels. The values of
the three pixels are summed. If the sum indicates a dot that is equal to
or darker than 2/3 black, the two outer thirds of the dot are set to black
and the central third is set to a shade of gray. If the sum indicates a
dot that is equal to or lighter than 1/3 white, central third of the dot
is set to white and the outer two thirds are set to a shade of gray. The
shades of gray are generated by using high addressability, and error
diffusion is used to diffuse the rounding off errors implicit in the high
addressability process.