Re: FWA / OBA compensation, user expectations
Re: FWA / OBA compensation, user expectations
- Subject: Re: FWA / OBA compensation, user expectations
- From: Tom Lianza <email@hidden>
- Date: Mon, 18 Apr 2011 07:26:38 -0400
- Thread-topic: FWA / OBA compensation, user expectations
Hello Jan-Peter
Always good to hear from you!
The largest problem we have is measuring a print in the "D50" booth. With
respect to both UV and the actual spectral output, the booths are quite
variable. Tools to characterize the material in the booth are quite tricky
because the booth drifts a bit too much for accurate measurement of the
copy.
Point 2 is still an issue after all these years. Display metamerism may be
an issue here. We are currently looking at this issue at Pantone. We have
seen instances where rather expensive instrumentation measures two display
technologies to be well less than 1 DE, but the displays are obviously
visually different. If we can't get two displays to agree, it is hard to
imagine we can get hardcopy and the display to agree visually. I am not
saying that we can't do an approximate job today, but there is a lot of work
to do in this area.
I am a little confused by your use of the word "compensation" in point 3.
What does this mean?
Regards,
Tom
On 4/18/11 7:09 AM, "Jan-Peter Homann" <email@hidden> wrote:
> 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
> ************************************************************************
> 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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