Problem with halftone

[Anonymous]

Hi all
we have cups 1.1.23 on FreeBSD 5.4 installed from ports.
We print without problem from Mac OSX but if we print from Windows
(cups with samba)
we get colors too clear. Reading our configuration we have halftone
set as the printer's default.
Anyone knows how to tune the halftone with samba, maybe modifying the ppd file?
p.s
the printer is a HP LaserJet 4200 Series and the ppd a HP LaserJet
4200 Series Postscript (recommended).
Thanks for your help

Valerio Daelli