QTR-Quadtone RIP

Let's start with a response to #4.  Not exactly.  Determining the K 
ink limit has more to do with determining the dMax of the particular 
ink on a particular paper without over-saturating the paper with 
ink. With some ink/paper combos, the dMax actually goes down with 
increasing ink load.  It is not blockup shadows that is creating 
what you see, it is the limit of the ink/paper combo to get any 
darker.  Maybe we are talking about the same thing?

#3.  Yes, but if you use black boost, then extra black ink is 
applied, thus increasing dMax at the darkest end.  On the other hand 
if you use overlap, then the dMax at the darkest end could be 
decreased as the density of the overlapping ink is less.

#2.  I'd try 80 or maybe 85%.  Experiment!

jr  

--- In QuadtoneRIP@yahoogroups.com, "alistair_owens" <owens@...> 
wrote:
>
> Hi All,
> 
> I am currently attempting for the first time to build some curves 
in 
> QTR for some new papers I am trying. I am using a ColorVision 
> measuring device. I am using Epson Ultrachrome inks. I am working 
> through Tom Moore's very comprehensive instructions.
> 
> I have some questions about the Characterizing the Ink Paper 
> Combination process:
> 1. I assume we are only concerned about the black strip on the 
> printout to assess ink limit. Is that correct?
> 
> 2. My black strip looks very blocked up at the darker end. This is 
> confirmed by measurements as follows:
> 55%	1.87
> 60%	2.00
> 65%	2.05
> 70%	2.07
> 75%	2.13
> 80%	2.16
> 85%	2.20
> 90%	2.22
> 95%	2.23
> 100%	2.23
> Based on this data, I am tempted to use a limit of 75%. Is this a 
> prudent interpretation or would 85% be better?
>  
> 3. I tried 70% just to experiment and the darkest swatch measures 
> 2.1 - does mean that if I use a 70% ink limit that my dmax becomes 
> 2.1 on that particular paper?
> 
> 4. Assuming the answer to (3) above is yes, is the whole 
> characterization process about optimising the compromise between 
dmax 
> and blocked up shadows?
> 
> Any and all responses very much appreciated.
> 
> Thanks and regards
> 
> Alistair Owens
> owens@...
>