AW: difficulties with base linearization
AW: difficulties with base linearization
- Subject: AW: difficulties with base linearization
- From: Henrik Holmegaard <email@hidden>
- Date: Thu, 22 Feb 2001 12:39:25 +0100
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