QTR-Quadtone RIP

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@...

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@...
>

Wow, those are some pretty hefty DMax values. You must be on Glossy  
stock.

I would concur with Jeff on this. I have wrestled endlessly with this  
very issue and tried lots of little tricks to work around it.

Then, I finally broke down and just chose a lower K ink limit and all  
of the problems went away.

I had been choosing the max K patch where the ink didn't get any  
darker at all, versus the first one that visually appeared the darkest.

Basically, be conservative. Choose the max K patch where you can  
REALLY see a difference in the next lighter patch. Not the one that  
is .02 darker in DMax.

You might not be choosing the darkest value your printer is capable  
of producing, but your prints will be noticeably smoother in shadow  
transition.

After you are done and everything looks great, then play with BOOSTK  
and GREYOVERLAP if you want to really push the envelope. My  
experience is  that the benefits are more cerebral than visual.  
Smoothness is more important than Dmax.

If you are getting Dmax over 2.0 your are splitting hairs any way.

Good luck.

James Haney


On Sep 11, 2007, at 2:49 PM, alistair_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@...
>
>
> 



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