Re: Status-E Press Control in North America.
Re: Status-E Press Control in North America.
- Subject: Re: Status-E Press Control in North America.
- From: Beisch Clemens <email@hidden>
- Date: Mon, 15 Dec 2008 21:13:28 +0100
Am 15.12.2008 um 19:39 schrieb Clark Steve:
I work prepress for a printer that installed two MAN Roland 23x29
multicolor presses in the last 4 years or so. The new presses have
scanning densitometers that work in Status-E. The SID cmyk numbers
in Status-E are quite a bit higher than the Status-T the pressroom
had been using prior to these installations. The pressman are, how
should I say it, reluctant to run to the higher numbers, and our
quality, print contrast etc has suffered.
Dimitris Ploumidis, Pacific Southwest Container:
(You can read more about this under: http://www.flexoglobal.com/
flexomag/08-July/flexomag-ploumidis.htm)
Filters
In order to assure consistency between different devices, the
illuminants used as light sources and the spectral curves of each
filter have been standardized. Unfortunately, there is more than
one standard! For the reflective densities of printing processes,
the U.S. uses wideband status T filters, Europe uses Status E, and
there are other filters with different bandwidths, like narrowband
Status I filters, that are useful for special applications. The
only difference between Status E and Status T filters is in the
spectral curve of the blue filter, which has a narrower band for
status E. This means that the same amount of the same yellow ink
would be read differently in the U.S. and Europe (a narrower
bandwidth of the blue filter provides a higher yellow density
reading). Wideband filters capture a broader range of reflected
light, allowing for a rather more accurate description of the
color of the ink, since a broader range of spectral reflectances
are accounted for. These filters, however, lack sensitivity for
purposes of process control, where slight variations in ink film
thickness can be obscured under the bigger sum of reflected light
that is taken into account. The reason for the choice of wideband
filters lies in the days where densitometry was used for film
separations and the focus was in capturing as much color
information as possible. The black ink is measured by the Visual
filter, which has a wide bandwidth since the black ink is not
spectrally selective.
Because of the problems by working with densities and color, printing
processes based on ISO 12647 define colors with CIE Lab values.
You can find informations about this under http://www.fogra.org -
http://www.eci.org and so on.
Density controll is ok after the main setup is done and you got your
own values.
Best regards,
Clemens Beisch
http://www.colorxact.net
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