Re: Numerical Analysis on: Photoshop Euro v2 profile & troubles
Re: Numerical Analysis on: Photoshop Euro v2 profile & troubles
- Subject: Re: Numerical Analysis on: Photoshop Euro v2 profile & troubles
- From: Olaf Drümmer <email@hidden>
- Date: Thu, 11 Dec 2003 10:02:34 +0100
Hi,
it seems in this context a couple of concepts often get mixed up. I'd
like to try to clarify a little bit:
(1) There are standards (actually, international - or should I say:
worldwide - standards like ISO 12647 with its parts addressing various
printing processes) or specifications (actually, often national - or
should I say US American ;-> - specifications like SWOP or GraCol. These
standards and specifications contain a set of rules "how thou shall
print" if you wish to follow the respective standard or specification.
The rules are about the inks to be used, dot gain, type of paper etc.
There are also rules about how to measure prints printed accordingly, so
that one can arrive at measurement (or characterization) data, and what
kind of charts to use that contain well defined patches (e.g. IT8.7/3 or
its successor candidate in ISO, ECI 2002, which happens to be a superset
of IT8.7/3).
Until here, no numbers exist that could be used for making profiles.
(2) Somebody in the industry may decide to follow the rules in (1) and
produce prints, measure them and collect measurement (or
characterization) data. This is a painful process, as it is more
difficult than often expected to actually arrive at prints where every
aspect (dot gain, densities, etc.) is really close to the aim values for
each process color and across the sheet. This is the main reason why it
is not really done that often. Nevertheless some industry associations or
graphic arts research institutes do this once in a while, and typically
are willing to share the achieved measurement (or characterization) data.
FOGRA and Ifra do it for free and for example simply upload the data to
their own website as well as to the registry maintained by ICC under
www.color.org, whereas SWOP for example asks for a couple of bucks before
you get hold of the data.
Now we have 'numbers' that characterize what you actually get when you
print certain CMYK patches on a given printing process. This is the
starting point for actually making ICC profiles.
(3) Now everybody can make ICC profiles from the above mentioned
measurement (or characterization) data. Alas, there is more than one way
to make ICC profiles from the same set of data: you could use different
versions of different tools from different vendors, you could use
different settings (black generation, long black vs. short black, gamut
mapping strategies, ...), and finally you could tweak manually what the
software generated automatically. Unless there is a bug in the software
or manual tweaking was done inappropriately, all the resulting profiles
are valid profiles. But of course they behave differently, and sometimes
wildly so. This is the main reason for example for FOGRA, not to bless
one out of many possible profiles for a given printing process and
proclaim it the official FOGRA profile.
Nevertheless, there are lots of folks in the industry that would need a
well crafted profile, but neither have the knowledge and expertise nor
the tools to create them themselves. Also, even if there are many
possible (professional quality) profiles it may often be convenient to
have one (kind of middle of the road, general purpose) profile that can
be used as a default. That's why the European Color Initiative took the
following decision:
- provide one set of ICC profiles based on the measurement (or
characterization) data collected by FOGRA for the relevant offset
printing conditions defined by ISO 12647-2 and provide this "basic set"
as a free download on their website.
- provide an "expert set" of ICC profiles (also as a free download) -
with variations for a couple of parameters -, for those who want to have
something slightly more specific.
So now we actually have got profiles. Whether you use the 'default'
profiles or make your own is up to you.
Interestingly, we have now received reports from some small surveys in
the Netherlands and Spain that the ISO standards based offset profiles
provided by ECI work exceptionally well and yielded consistent and very
pleasant results _IF_ printers followed all the rules in the standards
(one big issues often are the inks - if a printer uses inks that are not
within the ISO tolerances, it will be very difficult to print according
to ISO, no mater how much you tweak the press).
And one final remark: ISO is not a European thing, thus ISO 12647 is not
a European standard, and ISO 12647-2 is not Euroscale. The US as well as
countries like Japan or Brasil are active members of TC 130 - the
committee in ISO responsible for graphic arts/printing - and I do not
think you should call any of them 'European'...
Olaf Druemmer
European Color Initiative
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