I don't know if this helps, but newspapers (and anything printed on a real press)
are done by halftoning. I believe this is more a function that's done when it's sent
to the printer, either printed directly, or outputing film, or direct plate imaging -
rather than when the image is converted. For instance, if I print a tiff image to a
desktop inkjet printer, I'll get sprayed color; but if I print the same image through
a rip to a digital duplicator, for instance, I can get those dots.
This might not help, but might push you in the right direction. There is another
open source app called Scribus that is becoming a DTP app. It might help, and
the mailing list has some folks in the printing industry who can probably answer
Hope this hasn't just been useless rambling where you're concerned.