QTR-Quadtone RIP

Hello David. I will try to help but if anyone has better words, please
chip in.
Density, as it relates to QTR, means  how dark does the ink look once
printed on the paper. It's the nature of the relationships between the
inks and papers we use to vary with different printers,inks and papers
and, to some extent, even in variations in the surrounding environment
(eg: humidity,temperatures etc). It is also true that more ink does
not necessarily mean darker. There often comes a point where the
application of more ink to the paper actually makes it look lighter
rather than darker. The use of the terms density and ink limits in QTR
are referring to this effect. We all want the maximum darkness(d'max)
as dark as possible so we try to limit the amount of ink used to be
only just enough to give us the maximum visual blackness we can get.
In practice, generally you stop somewhere just before this at a point
where increasing the amount of ink laid down stops giving significant
increases in density. You do Not want to go beyond that to where you
reverse the ever increasing darkness curve.
What I just described is in reference to the K ink but it is equally
true of the lighter inks(grays). At some point they also will max out
in their density and give no more. So when you make the calibration
prints within QTR you are, first, trying to determine what the maximum
amount of black ink you can use is(limit) and, second, once this is
determined, testing for what the darkness of each of the other
inks(grays) is at that same limit and specifically in relation to the
black ink. Those figures are then used to derive the initial control
points used for bringing the various shades in during the printing
process so you get the proper distribution of tones.
Linearizing is just a continuation of the above process by adjusting
the curves that were derived from them such that they give equal steps
across the test step tablet and replicate it properly.

All said above is a simplification, though I believe accurate, of what
the QTR RIP does and or can do. It has many controls and, beyond a few
folks who post here, most of us don't have sufficient experience and
knowledge of rips overall to be proclaiming much in the way of wisdom
in the matter. That is why it sometimes takes a while to get suitable
answers to questions. We don't really relish the possibility of being
caught out as a case of the blind leading the blind. Most will wait to
see if someone far more knowledgeable will answer first. Those people
are usually very busy and have limited time to spend in doing so.

In regards to this overall thread (Not your query), some of the
responses or complaints are a bit like a 5 year old going into a rage
because daddy won't teach him to drive the family sedan. Never mind
that he's still too small to reach the pedals and can't yet read the
road signs.

Regards
Duane
 


--- In QuadtoneRIP@yahoogroups.com, "David" <dkfreed@...> wrote:
>
> I've posted this question before, but didn't really understand the 
> answers. So again, can someone help me understand what the ink density 
> and ink limit settings do? How are they different, the same?  Can 
> someone give an example of what changing these settings do?  
> 
> I have only a layperson's understanding, so looking for help. 
> 
> Best, David.
>