Jan-Peter,
My idea was first to normalize any ink set to CMYK lab values of ISO12647-2 and then to
measure red, green and blue wet traps to see which ink set has the best (closest) lab
values to RGB values in ISO12647-2.
To my complete surprise, ink set which we used showed up best in testing, three out of
five ink sets could not make black ink closer then deltaE 5.
When I realized that I wanted to see what is the average ink density, thinking if ink film
thickness is proportional to density (which I seriously doubt on wider scale) we should
choose ink which uses lowest ink film. But in this measurement there was also no
conclusive results.
I have also made tests with Aniva and Novaspace (not for iso12647) but just to see if this
gamut really so large, but results I got are clearly better but not spectacular. (although
it seems that novaspace printouts were more color intensive).
---
Someone must have been telling lies about Joseph K., for without having done anything
wrong he was arrested one fine morning.
mailto:marko@printel.hr
http://printel.hr
-----Original Message-----
From: Jan-Peter Homann [mailto:homann@colormanagement.de]
Sent: Wednesday, March 12, 2003 12:36 PM
To: eci(a)lists.transmedia.de
Subject: Re: [Eci] looking for best inks (trying to re-create iso12647-2 measurements)
Hello Marko Rakar
This field is not easy. Here in Germany, there is the idea to
standardize both digitalproof and press.
The FOGRA has made characterization data, the ECI delivers ICC-profiles
for free based on this data (ISO-profiles) and the printers should
optimize their presses for ISO 12647-2 conformity for easily matching an
proof based on the ISO-profiles.
If Ißm doing consulting for an printing comnpany, I always make some
testprints with images and compare also visually the result against an
digitalproof based on the ECI ISO-profiles.
The new ISO-Profiles are the best standard-profiles I have ever seen for
both separation and proofing. So you can advice your customers to use
the ISO-profiles for separtion and proofing and you will have no problem
to reach the colors of the proof while printing.
The actual problem is, that the ISO 12647-2 is actual in the state of
some optimization. The new characterization data from
http://www.forgra.org and the ISO-profiles from the ECI representing the
draft for the next version of the ISO 12647-2
You can find the slightly changed CIE Lab values for this draft in the
readme file for the new characterization-data at
www.forgra.org.
If you made testprints with some images, I would do a digital-proof
based on the ECI ISO-profiles and compare the result with your testprints.
Then I would choose an Inkset, which gives both good results for ISO
12647-2 compatibility and visual match to the proof.
:-) Jan-Peter Homann
Marko Rakar schrieb:
I have done small test today while trying to find
"best" ink for our
printing.
I have used five different ink sets from four manufacturers and
results are interesting.
My initial idea is to look for ISO12647-2 values on gloss paper
(smallest deltaE) for CMYK and then look for best deltaE values in R,
G, B colors as defined in ISO12647-2. I am thinking that inkset with
smallest average deltaE in this three colors should be choosen as
best.
I have also noticed that different ink sets requires completely
different densities and even relationships between colors (specialy
cyan vs. magenta) can be sometimes oposite.
Except for obvious properties like drying and stratching, what should
be my criteria, am I right to aim for ISO values, or should I consider
densities as well if we know (or at least think) that density is
related to ink film thickness?
any thoughts, suggestions?
p.s. I have also noticed that biggest difference is in black color,
where some inks simply can not reach ISO values (or at least to find
themselves on the same side of the graph) and best deltaE I could get
is 5 (or slightly smaller value) even when my paper on which I am
printing is deltaE .8 from iso value
---
Sometimes I get the feeling the whole world is against me, but deep
down I know that's not true. Some smaller countries are neutral.
mailto:marko@printel.hr
http://printel.hr
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