Hi Jo Brunenberg,
Thanks for the comment.
I agree with you regarding smearing. Science is not always enough. Common sense and
practical skills should go hand in hand with science.*
Keep in mind though, as I have said:
Calculating the "optimal level" of inks is the same as to find the LOWEST
possible use of printing ink and to minimize all possible printing problems that has to do
with to much ink.
With this technology we minimize
- mackel
- smearing
- drying time
- reflection and metamerism issues
and other problems that to much ink can create.
(More: the list can be made long: dirt on rollers in web presses, roll breaks (just got
values reg roll breaks from a job I did in the americas: they have with this technology
lowered the roll breaks from 1.5% to 0,5%: $$$!) etc etc.)
Because we will find the optimal ink values with this technique I usually disregard the
smearing issues during the "calibration" process.
I usually do like this.
1. Printing contrast test (with diagonal CM and KY fields and straight colour knifes in
the machine). I keep an eye on the smearing during this process though, at least in cold
set web and poor papers (se below), in the full tones as well as mixes and we normally
choose to be on the lower side if smearing is an issue with the paper used. When the
optimal density values are found:
2. ICC charts. Measure and calculate.
3. Reference print: check the quality, TIC, smearing etc.
The most sensitive papers regarding smearing I have seen so far are the so called enhanced
newsprint papers. Even though they are thicker than ordinary newsprint qualities they are
not nice at all, at least not for cold set web. Think these papers are made for heat set.
With this papers even full tones (100% of C, M, Y and K) are problematic so to say.
As we speak a swedish project are researching on this "enhanced" papers. Some
institute and three newsprint companies are involved. Study yet not published.
With the method I use, and if printing with full tone values that don't smear, we find
the best possible ink values.
- - -
DYNAMIC DEVICE LINK
Someone mentioned "dynamic device link" techonology regarding the subject I
started about TIC's. This is not what I am talking about, that is another chapter. A
dynamic device link techn is that the software read, not only RGB-profiles and convert,
but also read different CMYK-profiles; stop the process, calculate new device links and
then continue the process.
What I am talking about is the technology in how to calculate the device links: to find to
optimal values and not just use simpel GCR technologies.
- - -
IN GENERAL REG THIS STUFF
The base of what I am talking about is of course a serious ICC-profiling software. In my
case the profilegenerator is built-in to the software.
I have tried a few different programs that claim to "save ink" and/or convert
for example colour standards to press.
Some work some don't. One saved 3% CMY (very useful, LOL). Most of them "save
ink" but some create new colours: of course you can save ink if you make a blue sky
gray... :-)) How much to you save if you print BW? LOL!
I tried one (I keep to the subject and I avoid to mention names of software as you have
noticed), that do a good job from for example F39 to F39 but if you alter the setting to
F39 to press: crap. For me that is not very serious. The user can then not adapt the job
to the press but only "save ink". I guess the problem is that the manufacturer
know how to convert but have no knowledge about colour and printing. They probably made
the factory settings with a serious profiling software from another manufacturer but give
no tools to the user to make their own.
Conclusion reg this: if a software manufacturer can't even make a decent ICC-profile,
conventional or device link, how can they then make a device link based software that is
supposed to convert colour and "save ink"? ;-)
In other words: when the poorest manufactures of ICC-profiling softwares make "save
ink", "optimal ink" etc solutions: think twice before you purchase.
Personally I do not talk about "save ink" but about optimal values for all
colours, and no acceptance of colour deviations accept for 1 level in L, + being able to
match the colour to the press.
I just presented this at a university where I have supervised a master student in the
subject. I can send the essay from this engineer for them who wants it, on a personal
level (email me).
Cheers
A Seb
*/ Academic traditions in the graphic biz is a interesting subject itself. I will bring
this subject up here soon.
On Wednesday, April 16, 2008, at 12:01PM, <eci-en-request(a)lists.callassoftware.com>
wrote:
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> 1. Re: Total Ink Coverage based on what? (Jo Brunenberg)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Tue, 15 Apr 2008 12:40:50 +0200
>From: "Jo Brunenberg" <jo.brunenberg(a)rsdb.com>
>Subject: Re: [ECI-EN] Total Ink Coverage based on what?
>To: eci-en(a)lists.callassoftware.com
>Message-ID:
> <fc.000f5799042c89793b9aca009ee5c531.2bef68c(a)rotonet.rsdb.nl>
>Content-Type: text/plain; charset="iso-8859-1"
>
>Hi Sebastian,
>
>In my view defining TIC- (or TAC) values cannot only be a matter of scientific
calculation.
>In many cases in practice TAC values have been brought down in order to prevent
problems during printing and /or finishing.
>(Like bad drying / smearing etc.)
>
>Best regards,
>Jo Brunenberg
>Senior Technology Consultant
>ROTO SMEETS (RSDB)
>www.rotosmeets.com
>www.rsdb.com
>
>eci-en(a)lists.callassoftware.com,Internet writes:
>>I am new here. Hi all of you!
>>
>>Here is my first contribution; a question regarding:
>>
>>
>>Total Ink Coverage, TIC, for offset printing and the ink limits:
>>
>>
>>In the past, when I worked in a analogue photographic enlarger, the TIC was not
open for discussions: we could not alter it.
>>
>>When we bought a drum-scanner and where able to handle the values (and not
colours, by the way) electronically we where now able to decide what TIC we wanted.
>>The TIC's used where based on what people from Crosfield, Hell etc told us was
"good".
>>For coated offset printing values around 375% where often used. Same for uncoated
and even for newsprint sometimes (at least in my company) until we learned more, usually
from other people in the biz, and then we lowered the values for uncoated qualities.
>>
>>Conclusion so far: TIC's where based on opinions and experience.
>>
>>Photoshop and other softwares where introduced and followed the pattern as with
the drum-scanners.
>>
>>ICC-technology appeared. Good ideas but not very high quality until maybe five
years back in history, generally speaking.
>>Initially the ICC-technology created more "colour gurus" rather then
good quality.
>>TIC's still based on opinions, "gray hair" and
"experience".
>>
>>Some people in the biz started to alter values for TIC, often based on test-strips
with CMYK, from 400% and down: visual checks etc.
>>
>>Now:
>>For several years we have had the technology to actually calculate the best
possible TIC in a scientifical manner but still many colour gurus use the "good old
default" values. For example: 300 to 350 for coated, 260 to 319 (ECI) for uncoated
and 220 to 240 for newsprint.
>>
>>Why do we not calculate the TIC's scientifically? Today we have the tools, I
have the tools and we use them.
>>
>>One example: for coated offset printed within ISO standards we base a neutral
black on around 340-350% and we reach L=10.
>>>From that we allow the calculation to deviate delta 1 in L, not in a or b. A
engineer that I work with called this method JND, Just Noticeable Difference.
>>This way we reach a TIC in neutral black that is 233% (two hundred and thirty
three)! In other words: we print neutral black with L=11 with 233%.
>>Note: This technology do not set the TIC limit to 233 for all colours, it is
indvidual. A dark red can for example end up 244%. Normal ICC-profiles are in other words
a compromise: the TIC will limit all colours to one top value for TIC.
>>One more example: for newsprint we have reached a TIC, for neutral black, around
180% with a better L-value then ISOnewspaper26v4 - but a dark red can in the same print
reach 209%.
>>And so on.
>>
>>So, good bye to "opinions", "gray hair" and
"experience" or what is your opinion and experience regarding TIC?
>>
>>Best regards
>>A Sebastian
>>_______________________________________________
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