AW: difficulties with base Linearization
AW: difficulties with base Linearization
- Subject: AW: difficulties with base Linearization
- From: Ulf Großmann <email@hidden>
- Date: Thu, 22 Feb 2001 13:47:52 +0100
hey Henrik,
all new Profiles from BEST Germany are created without any filter. No filter
is used during measurement and in PO no Software filter is set. With the new
Version of BC (4.2.2) you get problems if you use the software filter from
PO, the Paper White is to Blue. We use for profiling the PO version 4.0.1 PC
(the newest Version from PO for Mac has the same algorithm inside for
creating profiles).
If we have problems with the Paper White, we do an correction via White
Point correction from PO 4.0.1 (direct change from the Lab-Value like in
ColorBlind Edit). We do also only global corrections inside the Profile and
no selective corrections, if we have too much problems, we start the
Profiling again with a new Baselinearization and new measurements. In my
opinion the measured profile with global corrections is the best one,
because any selective correction is a correction only for one reference
profile(separation profile, source profile or simulation profile).
Knowledge about measurement: We start to add the Information of the Profile
inside a Text File, which get it, if you download the Profile from our
internet side. This is ECI-Standard and includes all information about the
measurement.
Ulf
-----Urspr|ngliche Nachricht-----
Von: Henrik Holmegaard [
mailto:email@hidden]
Gesendet: Donnerstag, 22. Februar 2001 12:39
An: email@hidden
Betreff: AW: difficulties with base linearization
>
One Tpi from me, if you measure the Proofpaper with UV-Filter than you
>
should measure the Referece with UV-Filter too. All Profiles from BEST
>
Germany are measured without any Filter and I think our results are not
bad.
Ulf
So as not to confuse matters, I think that when Juris measures the
testchart he has printed on his proofer, then he should either
a. Set the Printopen 3/4 software filter for optical brightener to ON
and the UV filter on his spectro to OFF, or
b. Set the UV filter on his spectro to ON and the Printopen 3/4
software filter for optical brightener to OFF.
As I understand you, the BEST profiles do rely on a filter, but it's
the software filter in Printopen which corrects for blue in the media
white point. The perceptual and relative colorimetric tables are
media relative, so optical brightener affects the graybalance. Right
out of the box Printopen defaults to correcting for optical
brightener which is also why the BEST profiles sensibly maintain this
default. The BEST profiles weren't measured with the Printopen filter
off and a hardware UV filter on the spectrophotometer.
Juris has no way of knowing whether the Reference profile, which in
BEST terms is the profile for the production process (ColorBlind
calls it the Simulation profile, Adobe and Quark call it the
Separations profile), was measured with a UV filter. Usually this
information is viewed as private by the company that gives out the
profile, or the company just didn't keep a record of the measurement
procedure.
Reference / Simulation / Separations profile, they're equally good.
And they're equally confusing -:).
--
Henrik Holmegaard
TechWrite, Denmark
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