FWA / OBA compensation, user expectations
FWA / OBA compensation, user expectations
- Subject: FWA / OBA compensation, user expectations
- From: Jan-Peter Homann <email@hidden>
- Date: Mon, 18 Apr 2011 13:09:18 +0200
Hello all,
Tom Lianza asked about user expectations concerning measurement and ICC
color management of FWA / OBA (Optical brighteners) in papers (and inks).
From my point of view, the user expectations are as following:
1) Visual correct match between display and testprint in D50 viewing booth
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If a testprint with paper containing FWA / OBA is spectrally measured,
the measurement / profiling software should provide a compensation for
FWA / OBA during conversion fomr spectral data to D50 Lab data for ICC
profile generation.
An absolut colorimetric on the display of data from the testprint should
match the testprint itself in the D50 viewing booth.
2) Visual correct match between proof with no OBA and testprint in D50
viewing booth
******************************************************************
Proofmedia used for proofing according ISO 12647-7 (certified e.g. from
FOGRA, IDEAlliance and others) contains normally no FWA / OBA.
As a display also do not caontain FWA / OBA, it is easy to maintain a
good match between display and a proof using M0 measurements for
calibration / profiling and process control of proofs according ISO
12647-7 (FOGRA, GRACoL, SWOP...)
If we are now bringing the testprint with FWA / OBA in the game, the FWA
/ OBA compensation based on spectral measurement-data should provide out
of the box a good visual match between testprint and a proof (media with
no FWA / OBA).
3) OBA / FWA compensation independent from profile generation
***************************************************************
I think, it makes a lot of sense, when the FWA / OBA compensation can be
applied to the measurement-data, before the ICC-profile is calculated.
This allows e.g. to extract target values for process control in
hardcopy-proofing and softproofing from the compensated measurement-data.
4) Avialable tools for FWA / OBA compensation
***********************************************
Following tools are e.g. avaliable for FWA / OBA compensation from
spectral measurement-data:
- Heidelberg Color Tool (commercial)
- Argyll CMS (open source)
- XRite i1 isis with OBC (commercial)
(If other tools are avaliable, please feel free to notice us, in this
e-mail)
5) Future of ISO 12747 and standard characterization-data / profiles
(FOGRA / ECI, GRACoL, SWOP...)
***************************************************
Currently, ISO TC 130 is discussing a new categrozition scheme for
papers incl. target values for print standardization, which will lead to
new standard characterization-data and ICC-profiles in future.
The situation is quite tricky.
If we use M0 measurements for print standardization and process control
of printing and proofing, we will run in trouble, if the standard
characterization-data and ICC profiles are reflecting typical avaliable
papers today.
From the colormanagement perspective, it would make a lot of sense, if
standard characterization-data would be calculated with FWA / OBA
compensation. This would lead to much better results in softproofing or
hardcopy proofing on proofing media with no FWA / OBA.
But the result would be, that we M0 D50 L*a*b* values published in the
future version of ISO 12647 would not be consistent with the future
standard characterization-data.
One potential solution of this problem could be to use FWA / OBA
compensation method like the Heidelberg Color Tool. This method
compensates for 100% in paperwhite and reduces compensation to 0% for
the CMYK solids or color containing a 100% solid.
A future version of ISO 12647 could publish for the paperwhite a M0 D50
L*a*b* value and a typical FWA / OBA compensated value, which would be
the target in the standard characterization-data.
L*a*b* values for solids and secondaries would be the same in ISO 12647
and characterization-data.
Process control for printing and proofing would be be done with M0
measurements as today.
Woul be nice to hear some comments
Jan-Peter Homann
homann colormanagement --------- fon +49 30 611 075 18
Jan-Peter Homann ------------ mobile +49 171 54 70 358
Cotheniusstr. 3 -------- http://www.colormanagement.de
10407 Berlin -------- mailto:email@hidden
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