ed; the default value is 1.
You can use this to adjust the brightness of the output: for example,
if the image is too bright, increase the divisor.

<P>In keeping with (I believe) Fortran line-printer conventions,
input lines beginning with a <b>+</b> (plus) character are assumed to
&quot;overstrike&quot; the previous line, allowing a larger range of
gray values.

<P>If you're looking for something that creates an image of text,
with that text specified in ASCII, that is something quite different.
Use <b>pb