Print quality less with CUPS

[aiah metropolitan]

> Just a guess (you didn't tell how you set up your print queues):
> Try to print via CUPS with
>
> lp -d <queuename> -o raw plaintextfile
>

should translate to: lpr -P printer2 -o raw filename

Indeed the font "boldness/sharpness" is now the same as with LPRng.
But it also introduces a "staircase effect", i know how to fix the "staircast effect with LPRnr" (like adding filter=/usr/libexec/filters/lpf to the printcap file).
Does CUPS allow me to do the same ? (and how?)