QTR-Quadtone RIP

Tom;

Thanks for the suggestion, I'll have her try adding noise to the 
shadows, though what we're getting is not what you'd normally 
call 'microbanding'. But it might help just the same. 

BTW, I started using a densitometer recently to linearize my QTR 
curves-you'll be interested to know that your 'ideal density' charts 
are a LOT better! Thanks, after doing it a couple times manualy, I 
can now appreciate the effort it took to come up with those charts.

Steve Karafyllakis

--- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <r.t.moore@...> 
wrote:
>
> Steven
> 
> I think the cause may be ink overloading. This issue comes up
> regularly and an archive search for the phrases "banding gaussian"
> brings up a number of messages that might help. The one I have 
quoted
> below sort of sums up the issue (although others have found that
> adding noise didn't cure the problem, suggesting that its use won't
> cure all banding problems):
> 
> ...quote...
> Re: Banding with semi-gloss printing
> 
> --- In QuadtoneRIP@yahoogroups.com, "David Meddings" 
<meddings@f...>
> wrote:
> >
> > Quick followup on my own issue:
> >
> > Trying various dithering algorithms with 1440 super or 1440 
(both at
> > the better setting) had no effect.
> >
> > Printing at 2880 got rid of microbanding but introduced major 
bronzing
> >
> > Adding 12.5% monochromatic gaussian noise to the shadows and 
printing
> > at my normal settings solved the problem.
> >
> > So thanks to Tom Moore and indeed it looks as if there is an 
issue in
> > the gimp printing side of things.
> 
> Very much so. The gimp print drivers will exhibit microbanding
> whenever the total ink density (just all all 7 channel curves) 
exceeds
> 100%. This is easy to do with a glop curve, since we're typically
> adding glop at anywhere from 10-25% to curves that might have an 
ink
> limit at 80%, or black boost up to 100%.
> 
> I'm working on a driver with a layering concept as part of GRIP (if
> GRIP ever hits the point of being a useful public beta). The glop
> would go on an "aligned" layer so glop droplets always end up on 
top
> of colored ink droplets.
> 
> gimp print always interleaves ink, nothing ever really overlaps, 
and
> you cannot exceed 100% coverage (inks just displace each other, 
which
> can be a really, really weird looking effect when glop displaces 
black).
> ... end quote...
> 
> Tom Moore
> 
> --- In QuadtoneRIP@yahoogroups.com, "Steven Karafyllakis" <steve@>
> wrote:
> >
> > Hello All;
> > 
> > I'm tying to get a friend started with QTR on a 2200 and OEM UC 
inks, 
> > and we've run into an odd problem. She's on a Mac-Intel with OS 
10.4, 
> > using QTR 2.42.
> > The problem: she's getting PRINTED vertical faint minus-density 
lines 
> > in the 95%-100% zone. The lines are diffused, about 1/8" wide, 
and 
> > about 1.4" apart.  These are NOT pizza-wheel or roller marks, 
you can 
> > watch them being printed as the paper goes through. We've 
printed the 
> > same black field with both QTR and the Epson driver, and it ONLY 
shows 
> > up with QTR, there's no trace of it with the Epson driver.  Can 
anyone 
> > help with this? 
> > 
> > Thanks.
> > 
> > Steven Karafyllakis
> >
>