% halftone font with 32 levels of gray, characters "0" (black) to "V" (white)

mode_setup;
designsize:=64/pt; % that's 64 pixels

def makebox(text t)= enddef; % shut off boxes

picture prevchar;

prevchar=nullpicture;
for i=0 upto 31:
 beginchar(if i<10:i+ASCII"0"
 else: i-10+ASCII"A" fi,designsize/8,designsize/8,0);
 currentpicture:=prevchar;
 if i>0: fill unitsquare shifted (i mod 6,i div 6); fi
 prevchar:=currentpicture;
 endchar;
 endfor

font_quad=designsize/8;
end