Re: [ECI-EN] Differences ISO 12647-2 and FOGRA27L-30L
11 May
2005
11 May
'05
5 p.m.
Hi Jean-Marie,
Hi Erik
Due to this week's TC 130 meeting (the techical committee dealing with
e.g. ISO 12647-2) please understand that all relevant ISO member's
answers may take a while.
However two brief comments to your findings.
(1) differences between FOGRA27 and ISO 12647-2
Regarding this issue bvdm (German printer's association) currently is
preparing a paper explaining the reasons. The paper will be available
in German soon, probably in an English version as well. Regarding
greenish Cyan solid: The ink is within tolerance to the ISO aim values
but as you mentioned not representative for typical Cyan ink which is
reddish compared to the aim value.
(2) CIELAB coordinates of two- and three-color trapping
The aim values for red, green, blue and cmy as published in ISO
12647-2:2004 are subject to be changed. As mentioned above - official
news regarding to be expected timeline of publication may be available
after this week's ISO meeting.
Best regards,
Florian Suessl
Am 11.05.2005 um 11:20 schrieb Jean-Marie Govaerts:
Hi Erik,
Good to hear you followed my advise to check the difference between the
Fogra 27L-30L measurement data and the value described by ISO 12647-2
Indeed, it seems ISO 12647-2 has not been made on a 4 color press.
This
would be an explanation why the differences are so large especially for
the secondary colors. I think this is the reason why ISO tells us the
values of Red, Green and Bleu are not normative.
Maybe it would do a lot of good for all of us if the target values
given
us by ISO would have been based on a real production and not under
laboratory conditions. That way the values for the secondary colors
could also make part of the ISO.
We have the same conclusion for the cyan in Fogra 27L-30L. I have no
idea why, but apparently an other cyan was used for printing the Altona
test suite then the one described by ISO.
I hope this discussion will actually lead to an official answer how and
why there is a difference in the Fogra 27L-30L measurement data , and
the one described by ISO.
Regards,
Jean-Marie Govaerts
Senior Consultant
VIGC
--
Florian Suessl | Director Technology
MetaDesign AG | Leibnizstrasse 65 | 10629 Berlin
+49 30 59 00 54 246 | fax +49 30 59 00 54 111
fsuessl(a)metadesign.de | http://www.metadesign.de
----------
From: Erik Koldenhof
Reply To: eci-en(a)lists.transmedia.de
Sent: Tuesday, May 10, 2005 22:46 PM
To: eci-en(a)lists.transmedia.de
Cc: Henk Gianotten
Subject: [ECI-EN] Differences ISO 12647-2 and FOGRA27L-30L
Hey all,
Already some time ago, we noticed some strange issues with the ISO
standard and the FOGRA data.
Although it has been my intent to send our info on it to you all much
earlier, it actually never left our office.
But still, I would like to get a nice discussion going on the issues
found.
I've taken the liberty to upload a pdf report to our website which
describes some of the differences that we found between the ISO
12647-2:2004 standard,
and the FOGRA 27L-30L data.
Please feel free to get it, and use it for your personal
information/reviewing:
http://www.colormanagement.nl/Downloads/ISO-FOGRA_differences.pdf
The PDF file describes mainly the differences between the target
CIE-Lab color values in ISO, and the values found in the FOGRA data.
The visuals first show the differences between the two data sets, and
the last two pages show single (wet-dry) and FC (wet-in-wet) tests,
compared to both the ISO and the FOGRA data...
My most important questions are:
- Is it actually true that the ISO target values are based upon a
single-colour device (wet-in-dry printing condition)?
I know the FOGRA values are based upon fullcolour presses
(wet-in-wet), but I'm really curious for the 'official' ISO target
values.
- Which dataset is going to be altered towards the other, the FOGRA
27L-30L set of the ISO 12647-2 official references?
- Can we have some 'official' answers on the strange behavior the we
see in papertype 1 Cyan?
The FOGRA 27L is too green compared to every other pratical test
we've done so far.
I'm particular interested in which data the pratical endusers should
be using, both in prepress an in print.
This week, we'll be at GrafiVak 2005 exhibition, RAI Amsterdam, booth
01.536.
If you're in the neighborhood, pay us a visit if you please!
Colorful greetings,
Erik Koldenhof
------------------------------------------------------------
Koldenhof Grafimedia Expertise
PO Box1114
2280 CC Rijswijk
the Netherlands
tel. (+31) 70 336 02 42
fax. (+31) 70 394 11 87
www.koldenhof.nl
www.colormanagement.nl
e-mail: erik(a)koldenhof.nl
------------------------------------------------------------
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