Re: [ECI-EN] ECI-EN Digest, Vol 87, Issue 5
by Ingi Karlsson
1. Re: paper suited for printing according to ISO 12647-2-2013
(Jens Trost)
2. Re: paper suited for printing according to ISO 12647-2-2013
(Andreas Kraushaar)
Hello Jens
That is very interesting.
To make this information even more useful, it would be great if they could
add a section for the appropriate Fogra printing standard, - and add the
DE2000 v.s. the target.
Something like this:
LAB_L LAB_A LAB_B LAB_L LAB_A LAB_B Delta E-76 *Delta E2000*
*Category* *Manufacturer* *Measurement D50/2° M1* * Target M1*
PS 1 (Fogra 51) UPM UPM Finesse Premium Silk Coated 96,54 1,91 -5,72 95 1,5
-6 1,62 *1,12* OK
PS 1 (Fogra 51) Sappi Magno Satin, 170 gr. 95,48 1,53 -6,78 95 1,5 -6 0,92
*0,68* OK
PS 1 (Fogra 51) Sappi Magno Star, 170 gr. 94,8 1,4 -6,4 95 1,5 -6 0,47
*0,38* OK
PS 5 (Fogra 52) UPM UPM Fine Uncoated 94,39 3,51 -10,76 93,5 2,5 -10 1,55
*1,40* OK
In general I think it would be a good idea to stop releasing M0 values now
- for color and for paper white. It is not helping anyone. The actual white
point, - i.e. the one you actually *see*, is only revealed when measured
with M1, so 6 years after M1 became the official standard for measurement
of color and paper, I think it is time that printers who are in business
park their M0 devices spectral devices.
It would actually be a good first step to only release M1 values for paper
white (and M2 is also useful information to check the amount of OBA).
It is especially embarrassing for paper manufacturers that obviously want
to be on top of their game and have done their homework and decided years
ago to include D50/2° CIELAB measurements and the relevant Fogra standards
suited for printing on their paper, that their specs still recommend Fogra
39 or Fogra 47 for paper that is in fact not appropriate for printing to
these standards, - unless of course if you continue to ignore the OBA. It
is embarrassing because they themselves put the OBA into the paper pulp
during production.
Best regards
Ingi
mið., 6. mar. 2019 kl. 11:04 skrifaði <
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>
> 1. Re: paper suited for printing according to ISO 12647-2-2013
> (Jens Trost)
> 2. Re: paper suited for printing according to ISO 12647-2-2013
> (Andreas Kraushaar)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 6 Mar 2019 06:55:47 +0100
> From: Jens Trost <newsletter(a)jenstrost.de>
> Subject: Re: [ECI-EN] paper suited for printing according to ISO
> 12647-2-2013
> To: eci-en(a)lists.callassoftware.com
> Message-ID: <371A09F1-5514-4EC6-8F1D-CE299CF57C3C(a)jenstrost.de>
> Content-Type: text/plain; charset=us-ascii
>
> Hello Ingi,
>
> it may be not exactly what you are looking for, but proof.de just
> released a list of various paper whites across many availabe papers.
>
> It's german based so I don't know if it's any help to you, but it's worth
> a look:
>
> https://shop.proof.de/info/paper-white.html
>
>
> Best regards
> Jens
>
>
> > Am 01.03.2019 um 14:18 schrieb Ingi Karlsson <ingi(a)spot-nordic.com>:
> >
> > Just one small comment on suitable production paper.
> >
> > It would be nice if paper manufacturers could contribute and send a list
> of suited paper for production printing to Fogra 51 and Fogra 52 by doing
> their own measurement with M1, - which would make that paper suited for
> printing according to ISO 12647-2-2013.
> >
> > I have not done a lot of measurements, but the specs I have found about
> commercially available papers either have nothing about white point to D50,
> - or the measurement is M0 and the suggested profiles for the paper are the
> old Fogra 39 / Fogra 47 - based on the M0 measurement (even if the paper is
> almost perfectly correct for printing according to the current ISO standard
> according to my own measurements). That again means that the paper is in
> fact NOT suited for printing according to Fogra 39 / Fogra 47 because of
> the OBA that is ignored when measured with the M0 filter.
> >
> > There are however no doubt papertypes out there that, when measured with
> the M1 - and M0 condition are appropriate for printing according to Fogra
> 39, Fogra 47.
> >
> > In fact it would be useful if Fogra would start offering paper
> manufacturers to certify their production paper as suited for commercial
> printing according to Fogra 51 / Fogra 52.
> > It would surely make my life easier if I could look the suitable papers
> up on the Fogra website, - and I'm sure for many others as well, - even
> just color conscious print customers and designers that would prefer to
> keep their colors in check cross media.
> >
> > Best regards and wishing you a nice weekend
> >
> > Ingi Karlsson
>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 6 Mar 2019 06:35:09 +0000
> From: Andreas Kraushaar <Kraushaar(a)fogra.org>
> Subject: Re: [ECI-EN] paper suited for printing according to ISO
> 12647-2-2013
> To: "eci-en(a)lists.callassoftware.com"
> <eci-en(a)lists.callassoftware.com>
> Message-ID: <1551854100626.54119(a)fogra.org>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hello Ingi, all,
>
> we considered such a certification but refrain from starting it for
> various reasons:
>
> - limited interest by the manufacturer
> - communicate the uncertainty budget for the actual measurements (due to
> "normal" device variations) - there is no one CIELAB value for a paper.
> - unclear requirements for re-certifications (if the recipes are changed)
> - a lot of information by some manufacturer (sometimes unstructured, I
> agree)
>
> regards
> Andy
>
>
> ________________________________________
> Von: eci-en-bounces(a)lists.callassoftware.com <
> eci-en-bounces(a)lists.callassoftware.com> im Auftrag von Jens Trost <
> newsletter(a)jenstrost.de>
> Gesendet: Mittwoch, 6. M?rz 2019 06:55
> An: eci-en(a)lists.callassoftware.com
> Betreff: Re: [ECI-EN] paper suited for printing according to ISO
> 12647-2-2013
>
> Hello Ingi,
>
> it may be not exactly what you are looking for, but proof.de just
> released a list of various paper whites across many availabe papers.
>
> It's german based so I don't know if it's any help to you, but it's worth
> a look:
>
> https://shop.proof.de/info/paper-white.html
>
>
> Best regards
> Jens
>
>
> > Am 01.03.2019 um 14:18 schrieb Ingi Karlsson <ingi(a)spot-nordic.com>:
> >
> > Just one small comment on suitable production paper.
> >
> > It would be nice if paper manufacturers could contribute and send a list
> of suited paper for production printing to Fogra 51 and Fogra 52 by doing
> their own measurement with M1, - which would make that paper suited for
> printing according to ISO 12647-2-2013.
> >
> > I have not done a lot of measurements, but the specs I have found about
> commercially available papers either have nothing about white point to D50,
> - or the measurement is M0 and the suggested profiles for the paper are the
> old Fogra 39 / Fogra 47 - based on the M0 measurement (even if the paper is
> almost perfectly correct for printing according to the current ISO standard
> according to my own measurements). That again means that the paper is in
> fact NOT suited for printing according to Fogra 39 / Fogra 47 because of
> the OBA that is ignored when measured with the M0 filter.
> >
> > There are however no doubt papertypes out there that, when measured with
> the M1 - and M0 condition are appropriate for printing according to Fogra
> 39, Fogra 47.
> >
> > In fact it would be useful if Fogra would start offering paper
> manufacturers to certify their production paper as suited for commercial
> printing according to Fogra 51 / Fogra 52.
> > It would surely make my life easier if I could look the suitable papers
> up on the Fogra website, - and I'm sure for many others as well, - even
> just color conscious print customers and designers that would prefer to
> keep their colors in check cross media.
> >
> > Best regards and wishing you a nice weekend
> >
> > Ingi Karlsson
>
> _______________________________________________
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>
>
> ------------------------------
>
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> End of ECI-EN Digest, Vol 87, Issue 5
> *************************************
>
5 years, 1 month
- 2
- 1
Re: [ECI-EN] ECI-EN Digest, Vol 87, Issue 1
by Ingi Karlsson
Just one small comment on suitable production paper.
It would be nice if paper manufacturers could contribute and send a list of
suited paper for production printing to Fogra 51 and Fogra 52 by doing
their own measurement with M1, - which would make that paper suited for
printing according to ISO 12647-2-2013.
I have not done a lot of measurements, but the specs I have found about
commercially available papers either have nothing about white point to D50,
- or the measurement is M0 and the suggested profiles for the paper are the
old Fogra 39 / Fogra 47 - based on the M0 measurement (even if the paper is
almost perfectly correct for printing according to the current ISO standard
according to my own measurements). That again means that the paper is in
fact NOT suited for printing according to Fogra 39 / Fogra 47 because of
the OBA that is ignored when measured with the M0 filter.
There are however no doubt papertypes out there that, when measured with
the M1 - and M0 condition are appropriate for printing according to Fogra
39, Fogra 47.
In fact it would be useful if Fogra would start offering paper
manufacturers to certify their production paper as suited for commercial
printing according to Fogra 51 / Fogra 52.
It would surely make my life easier if I could look the suitable papers up
on the Fogra website, - and I'm sure for many others as well, - even just
color conscious print customers and designers that would prefer to keep
their colors in check cross media.
Best regards and wishing you a nice weekend
Ingi Karlsson
fös., 1. mar. 2019 kl. 02:36 skrifaði <
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> Today's Topics:
>
> 1. Re: Issues related with the switch from FOGRA39/47 to
> FOGRA51/52 (Refik Telhan)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 01 Mar 2019 05:28:24 +0300
> From: Refik Telhan <rtelhan(a)ofset.com>
> Subject: Re: [ECI-EN] Issues related with the switch from FOGRA39/47
> to FOGRA51/52
> To: <eci-en(a)lists.callassoftware.com>
> Message-ID: <1D1CB34E-5A04-4A2E-ABA3-8CD000D4EC4E(a)ofset.com>
> Content-Type: text/plain; charset="utf-8"
>
> Dear Florian,
>
>
>
> I am currently working on two related but separate lines.
>
>
>
> On the one hand, I am experimenting with different levels of gray axis
> correction of the perceptual rendering intent in both FOGRA51 and FOGRA52.
> I already have 6 variants of each dataset (Keep Gray Axis set to 0, 3, 4,
> 5, 7 and 10) generated with Color Toolbox v18 made possible by the generous
> help of my colleagues from the local Heidelberg support team.
> Interestingly, majority of my colleagues have picked 4 in both datasets.
> Now that CoPrA v5 started offering incremental control on the two different
> algorithms, namely minimum compression and absolute compression, for the
> perceptual rendering intent. CoPrA also enables a two-way control of the
> gray balance, you can make it warmer, but you can also make it much cooler.
> I am currently generating the variants in the warmer direction. But at this
> point I have to underline that fact the kind of gray axis correction Color
> Toolbox is making is mostly effective in the lover half of the tonal range.
> Apparently, the kind of gray axis
> correction done by CoPra is effective through the full range.
>
>
>
> The second line is mostly empirical. To retain as much experience as
> possible from the FOGRA39L/47L era, I have simply modified the white point
> of the FOGRA39L dataset to bring it in line with FOGRA51. As the white
> point of FOGRA51 has been measured in M1 mode, to avoid mixing of values
> from different measurement mode, I have grabbed the white point of a real
> paper in M0 mode that actually hits the FOGRA51 value in M1 mode. The
> CIELAB value is 95, 1, -4.5 (M0). Once I find an uncoated stock that
> measures 93.5, 2.5, -10 in M1 mode, I will measure it in M0 mode to modify
> FOGRA47L.
>
>
>
> I have started generating profiles with the modified/revised FOGRA39L
> dataset, namely FOGRA39R. As the FOGRA51 compatible proofing substrate that
> I am using closely matches this real paper, I hope to have an ink-free
> paper white simulation during proofing. As this dataset is holding the same
> CMY balance with FOGRA39L, we may even be able to do away with using the
> perceptual rendering intent to correct the gray axis.
>
>
>
> Under all circumstances, we probably have to focus on getting the total
> ink film neutral gray regardless of the paper color (with or without OBA).
> The intricate interaction between the UV component of the M1 mode with the
> unprinted and the printed paper is probably making things quite complicated
> when it comes to stripping of the ink film color from the paper color. This
> is why an trying to avoid the M1 measurement mode. I will also be testing
> an old i1Pro with a physical UV-cut filter to see how it relates to the
> mathematically simulated M2 mode of an i1Pro2. I am still curious about the
> reason for the apparent suppression of yellows in all colors. The new
> datasets are telling the profiling packages that there is too much yellow.
> Hence yellow is being knocked down everywhere. We need the UV component in
> the spectro to see and measure the fluorescence in the paper. We probably
> have to the read the profiling charts in both M1 and M2 (preferably with a
> physical UV-cut filter) m
> odes and extract the ink film color by correlating these two datasets.
>
>
>
> I will be coming back with more once I finish my planned testing.
>
>
>
> Thanks and regards,
>
>
>
> --------------------------------------------------------
>
> Refik Telhan, EE B.Sc.
>
>
>
> Light and Color Management Consultancy
>
>
>
> Aydogdu Sokak 12A, Tarabya Mahallesi
>
> Sariyer, 34457, Istanbul, Turkey
>
>
>
> Mobile: + (90) (532) 426 21 87
>
> --------------------------------------------------------
>
>
>
>
>
>
>
> ?On 28.02.2019 18:33, "florian(a)suessl.de" <
> eci-en-bounces(a)lists.callassoftware.com on behalf of florian(a)suessl.de>
> wrote:
>
>
>
> ??? Dear Refik,
>
> ???
>
> ????The learning from this very fruitful discussion is, that in the future
> (ECI et all) will pay more attention to the gray reproduction of the
> perceptual rendering intent.
>
> ????
>
> ????And for users, the learning is, to switch to perceptual if they are
> not pleased with the gamut mapping of rel.col+bpc colour conversions.
>
> ???
>
> ????Up to FOGRA39 the recommendation (except for newsprint) was the use of
> relative colorimetric with black point compensation in order to achieve
> better consistency among profile of different profiling packages and to
> reduce color deviations of in gamut colours. As you pointed out, there were
> no complaints against rel.col+bpc. Athough even in the older FOGRA39/47
> days there were and are good reasons for choosing perceptual.
>
> ???
>
> ????Working on FOGRA51 and 52, we were braking new ground. Along with PSO
> Coated v3 and PSO Uncoated v3 several fundamental changes were introduced:
> New lighting (UV content), new measurement condition M1, new proofing
> substrates with oba content similar that of paper used in production
> printing.
>
> ????
>
> ????Changing several core aspects, there always is a substantial risk of
> introducing unexpected side effects ? such as ?cool colors? or as you
> mention: unexpected lack of yellow. We (Fogra, ECI) focused on proof to
> print precision; i.e. invested a lot of effort, e.g. several printing tests
> and the evaluation of more than one characterization data set candidates
> (see ECI Fred 15 project). Following the discussion, all of us seem to
> agree, that this goal is achieved. And is an important one as a good print
> to proof match is the best way to check upfront, whether or not the
> resulting colours are ok or not. And to apply changes at the prepress stage
> if needed.
>
> ???
>
> ????You make a very understandable point asking for a bit of continuity
> between the FOGRA39L/47L and FOGRA51/52 worlds.
>
> ????
>
> ????Unfortunately this is *not possible for rel.col+bpc* conversions. By
> definition in the ICC standard rel.col is clearly defined ? no way for
> tweaking in gamut colours. All we can do is to edit the gray reproduction
> of the *perceptual* intent while creating future ECI profiles. Which
> probably is, what you mean by saying ?which I think is possible?. Sharing
> and discussing the results of your planned tests will be a good basis. So
> thanks in advance for your valuable contribution.
>
> ???
>
> ????
>
> ????Best Regards,
>
> ??? Florian
>
> ???
>
> ????> Am 28.02.2019 um 13:08 schrieb Refik Telhan <rtelhan(a)ofset.com>:
>
> ??? >
>
> ????> Dear Claas,
>
> ??? >?
>
> ????> I haven?t said that there is a problem with the paper white of
> FOGRA51 and FOGRA52. In fact, this is the one thing that FOGRA51 and
> FOGRA52 got right.
>
> ??? >?
>
> ????> My objection is to the new CMY balance (which is drastically
> different from FOGRA39L and FOGRA47L). What has been working with
> FOGRA39L/47L is not working any more.
>
> ??? >?
>
> ????> Rel.Col does not take the paper color into account, because it is
> designed that way. This was also true when we were making FOGRA39
> separations. But it was working. The old Rel.Col+BPC conversions created
> acceptable grays on real papers loaded with OBA. Why have we lost it?
>
> ??? >?
>
> ????> If the perceptual rendering intent is not set to do gray axis
> correction when the profile is being created, it basically creates the same
> CMY balance. And the profiles released by ECI for FOGRA51 and FOGRA52 have
> this function switched off. CoPrA5 and Color Toolbox can do this correction
> incrimentally. I have already tested different settings in both packages.
> But this function has a subjective side. Different people may see the
> neutrality at different levels of correction. And this only helps in the
> lower half of the tonal range. The main discussion is with the lack of
> yellows in the upper half, mid-tones to shadows.
>
> ??? >?
>
> ????> We are now discussing profiles and datasets for the masses. I am
> only asking for a bit of continuity between the FOGRA39L/47L and FOGRA51/52
> worlds, which I think is possible.
>
> ??? >?
>
> ????> Best regards,
>
> ??? >?
>
> ????> --------------------------------------------------------
>
> ??? > Refik Telhan, EE B.Sc.
>
> ??? >?
>
> ????> Light and Color Management Consultancy
>
> ??? >?
>
> ????> Aydogdu Sokak 12A, Tarabya Mahallesi
>
> ??? > Sariyer, 34457, Istanbul, Turkey
>
> ??? >?
>
> ????> Mobile: + (90) (532) 426 21 87
>
> ??? > --------------------------------------------------------
>
> ??? >?
>
> ????>?
>
> ????> From: <eci-en-bounces(a)lists.callassoftware.com> on behalf of Claas
> Bickeb?ller <lists(a)bickeboeller.name>
>
> ??? > Reply-To: <eci-en(a)lists.callassoftware.com>
>
> ??? > Date: 28 February 2019 Thursday 11:11
>
> ??? > To: <eci-en(a)lists.callassoftware.com>
>
> ??? > Subject: Re: [ECI-EN] Issues related with the switch from FOGRA39/47
> to FOGRA51/52
>
> ??? >?
>
> ????> Dear Refik,
>
> ??? >?
>
> ????> again:
>
> ??? >?
>
> ????> The problem is not the paper white of FOGRA51 or FOGRA52.
>
> ??? > It is your, sorry, wrong expectation.
>
> ??? >?
>
> ????> Relative colorimetric rendering is well defined for in gamut colours.
>
> ??? > The chromatic adaptation has to be the Wrong von Kries and
> everything has to be mapped relative to the white point.
>
> ??? > If you do not like the result, do not use rel.col.
>
> ??? >?
>
> ????> If you see the same with perceptual, the creator of the
> profile/gamut mapping decided to use a white point relative mapping of the
> grey axis (which is quite common).
>
> ??? > Again, if you do not like it, create a profile with a perceptual
> mapping that you like.
>
> ??? >?
>
> ????> If you have CoPrA 5 try ?absolute compression? and you?ll have the
> opposite of rel.col
>
> ??? > Then you might see that the ?issue? is related to the gamut mapping
> and _not_ the measured values.
>
> ??? >?
>
> ????> My 2 cents
>
> ??? >?
>
> ????> Claas
>
> ??? >?
>
> ????>> Am 28.02.2019 um 00:51 schrieb Refik Telhan <rtelhan(a)ofset.com>:
>
> ???>>?
>
> ????>> Dear Claas,
>
> ??? >>?
>
> ????>> Yellow is not only a UV-blocker but also a blue-blocker. As it is
> initially blocking the incoming UV, the OBA is not triggered at all. So no
> secondary blue emission (peak wavelength of the radiation is around 430 nm)
> is taking place. Whatever the case is, from a practical standpoint, M0, M1
> and M2 measurements of a solid yellow patch produces identical results. Out
> of the four primaries, only magenta is letting both the UV and the blue
> through. You will have different readings for M0, M1 and M2 readings of a
> solid magenta patch. This intricate relationship, between the illuminants
> of the spectro, the ink film, the paper as a reflector and the UV-induced
> OBA emission, is making things quite complicated.
>
> ??? >>?
>
> ????>> Probably other spectrometric device manufacturers are also using
> similar mathematical techniques to sense and separate the fluorescence from
> the paper color. In the end, we actually need to separate the color of
> paper from the color of the ink film. To be able to build profiles which
> would give us the paper relative colorimetric conversion, we need the color
> of the ink film alone not the paper. The combined color is only useful when
> we are trying to simulate it in absolute colorimetric terms. What had been
> relatively easy or straightforward in the FOGRA39 dataset, probably with
> help of the low OBA content of its paper, has become problematic with
> FOGRA51 and to a greater extent with FOGRA52. Probably because the way the
> measurement data is stripped off the fluorescence and the paper color, the
> profiling packages are now thinking that there is an abundance of yellow
> color that can be dispensed with.
>
> ??? >>?
>
> ????>> I have recently tried to generate a high GCR profile from the
> FOGRA52 dataset in X-Rite?s i1Profiler. For the input value of L*=a*=b*=0,
> the CMYK output for the perceptual rendering intent is C=99.9, M=52, Y=3
> (yes, three per cent) and K=91.9, L* out is 29.5 with a*=1.2 and b*=-3.7.
> With exactly the same settings, the profile generated out of the FOGRA47L
> dataset displays a totally different picture. For L*=a*=b*=0, the CMYK
> output is, C=87.5, M=67, Y=50.3 and K=94.9 and L* out is 27.8 with a*=0.3
> and b*=-0.9. On real uncoated offset papers with an M0 b* value in the
> range of -8 to -10 (in M1 terms the b* can go as down as -15), I find even
> the FOGRA47L a bit weak on the yellow side. I have no words to say for the
> FOGRA52 conversion. The situation is not as bad as this in the FOGRA51
> world, but it still leaves much to be desired. But let me also underline
> the fact that this deficiency of yellow is not limited to the gray axis.
> This whole issue came to my attention with
> a complaint about yellows in the skin tones. The deficiency is
> everywhere.
>
> ??? >>?
>
> ????>> The problem is also not limited to the relative colorimetric
> intent. Switching to perceptual in its current form of the profile changes
> nothing. The conversions above are perceptual. In the currently released
> FOGRA52-based profile gray axis correction is totally switched off. I have
> experimented with different levels of gray axis correction with help of
> colleagues in the local Heidelberg team using Color Toolbox v19. Using a
> halfway setting, a result pleasing to the eye can be achieved. But it only
> helps in the lower half of the tonal range, from highlights to mid-tones.
> The deficiency in the mid-tone to shadow range still remains unaddressed.
>
> ??? >>?
>
> ????>> At this point, I must also underline the fact that most of my
> objections are based on a comparative analysis between FOGRA39/47 and
> FOGRA51/52. The days of the drum scanner were long gone before the
> FOGRA39/47 era. We had no issues with the conversions made with these
> profiles from the digital images. They only needed a paper white fix.
>
> ??? >>?
>
> ????>> When duly processed, you would not be able to differentiate drum
> scanned images from digitally captured ones. Hence, what was good for the
> last ten years can still produce good results with a rather quick paper
> white fix.
>
> ??? >>?
>
> ????>> A printer?s life is already too complicated, let us make it simpler
> whenever and wherever possible.
>
> ??? >>?
>
> ????>> Best regards,
>
> ??? >>?
>
> ????>> --------------------------------------------------------
>
> ??? >> Refik Telhan, EE B.Sc.
>
> ??? >>?
>
> ????>> Light and Color Management Consultancy
>
> ??? >>?
>
> ????>> Aydogdu Sokak 12A, Tarabya Mahallesi
>
> ??? >> Sariyer, 34457, Istanbul, Turkey
>
> ??? >>?
>
> ????>> Mobile: + (90) (532) 426 21 87
>
> ??? >> --------------------------------------------------------
>
> ??? >>?
>
> ????>> From: <eci-en-bounces(a)lists.callassoftware.com> on behalf of Claas
> Bickeb?ller <lists(a)bickeboeller.name>
>
> ??? >> Reply-To: <eci-en(a)lists.callassoftware.com>
>
> ??? >> Date: 20 February 2019 Wednesday 12:29
>
> ??? >> To: <eci-en(a)lists.callassoftware.com>
>
> ??? >> Subject: Re: [ECI-EN] Issues related with the switch from
> FOGRA39/47 to FOGRA51/52
>
> ??? >>?
>
> ????>> Dear Refik,
>
> ??? >>?
>
> ????>> your findings regarding yellow are not surprising.
>
> ??? >> Yellow inks are often blocking (reflecting and absorbing) UV light.
>
> ??? >> But the main contribution that you do not see any influence of the
> OBA is that yellow filters the blue/purple light that is emitted by the OBA.
>
> ??? >>?
>
> ????>> The explanation for your findings regarding cyan is that the
> emission of the OBA is in the same wavelength area where cyan has the
> highest reflection.
>
> ??? >> For a typical ink film thickness the fluorescence part of the total
> radiance is around only 10% or less for a coated paper.
>
> ??? >>?
>
> ????>> Also one hint: Be careful when you look at M0 values. They depend
> on the instrument you are using.
>
> ??? >> In our instruments we get the M0, M1 and M2 values based on a
> patented method which first separates the pure reflection from the
> fluorescence and then applies the measurement light source (it is not a
> filter BTW) mathematically.
>
> ??? >> Hence ?our? M0 is the result you?d get from a perfect tungsten lamp
> (CIE illuminant A).
>
> ??? >> If you use an instrument with a real life tungsten you most
> probably get a different result.
>
> ??? >>?
>
> ????>>?
>
> ????>> Regarding the discussion about the grey axis, I can only repeat
> what I already commented.
>
> ??? >> Relative colorimetric is specified to render the grey axis relative
> to the paper white.
>
> ??? >> If you do not like the result, use perceptual.
>
> ??? >> In general perceptual was the intended RI for image conversions
> already when the ICC standard was created.
>
> ??? >> From my point of view rel.col. bpc only got popular because older
> profiling engines' perceptual mappings changed the image a lot compared to
> the RGB original.
>
> ??? >> This came, as far as I know, from the fact that these mappings were
> based on the experience with images created by a drum scanner where the
> original had a very high dynamic range.
>
> ??? >> When such a mapping is used for today?s images created by digital
> cameras with a much lower dynamic range the result is not ideal/as
> expected/as desired whatever you want to call it.
>
> ??? >>?
>
> ????>> Today?s engines have mapping strategies that are optimized for
> today?s image creation scenarios.
>
> ??? >>?
>
> ????>> So people need to be educated that rel.col bpc is not the best
> choice for today?s printing conditions.
>
> ??? >>?
>
> ????>> So it is not the measurement condition that causes the ?issue? you
> see, it is the gamut mapping.
>
> ??? >>?
>
> ????>> Best regards
>
> ??? >>?
>
> ????>> Claas?????
>
> ????>>?
>
> ????>>?
>
> ????>>> Am 20.02.2019 um 02:28 schrieb Refik Telhan <rtelhan(a)ofset.com>:
>
> ??? >>>?
>
> ????>>> Dear Florian and All,
>
> ??? >>>?
>
> ????>>> I have now added a new folder, namely ?2019-02-20?, into the
> Dropbox folder that I have shared with some of you. One contains the
> roundtrip to PSO Coated v3. And the other is the separation with my
> M2-based profile which is then tagged with M1-based profile before coming
> back to CIELAB in as>bsolute colorimetric intent.
>
> ??? >>>?
>
> ????>>> Interestingly, the white point of the M2-measured dataset is 95,
> 0, 0 (94.819, -0.307, 0.368 to be precise). Apparently, when this
> commercially available matt coated paper is ripped off its OBAs it becomes
> ideally neutral. The CMY balance of the profile made out of this dataset is
> favoring the yellow channel. Yellow channel comes out to be above the
> magenta channel, not equal or below.
>
> ??? >>>?
>
> ????>>> It is all boiling down to the question of what is acceptable as a
> visual paper relative neutral gray. FOGRA39 was doing OK. FOGRA47 needed
> some yellow boost. We always helped yellows a bit in real life. FOGRA51
> definitely needs more yellow. And we have not even started talking about
> FOGRA52. I did one heavy GCR version in i1Profiler and ended up with 3% of
> yellow at the dark end of the range. I will generate more high GCR versions
> of the FOGRA52 dataset with different packages throughout this week.
>
> ??? >>>?
>
> ????>>> As we are really looking for a paper relative neutrality, we are
> in fact targeting the absolute neutrality of the ink film created by the
> combination of C-M-Y channels. For this purpose we can leave K alone. In
> other words, our mesurements should somehow be stripping off the substrate
> color. And OBAs are making things very complicated. I have really started
> thinking about the usefulness of M1 measurement mode in measuring color
> patches with a yellow coverage. While it is indispensable in assessing the
> presence and the amount of OBAs in the uprinted substrate, it gets things
> complicated when inks come in the way. Let us not forget that yellow ink is
> a UV-cut filter. When yellow is printed on any substrate, no UV radiation
> reaches the substrate. Hence, the OBAs receive no excitation. With yellow
> ink on top, any substrate with or without OBAs become impervious to UV.
>
> ??? >>>?
>
> ????>>> As I have made M0, M1 and M2 measurements of the same profiling
> chart, let me give you the M0, M1 and M2 results of some critical patches,
>
> ??? >>>?
>
> ????>>>?
>
> ????>>> Solid Yellow Patch
>
> ??? >>> #958 C=0 | M=0 | Y=100 | K=0
>
> ????>>>?
>
> ????>>> M0?????? 86.761, -3.318, 91.430
>
> ??? >>> M1?????? 86.751, -3.264, 90.921
>
> ??? >>> M2?????? 86.912, -3.412, 92.064
>
> ??? >>>?
>
> ????>>> Solid Magenta Patch
>
> ??? >>> #775 C=0 | M=100 | Y=0 | K=0
>
> ??? >>> M0?????? 47.116, 74.537, -3.434
>
> ??? >>> M1?????? 47.306, 74.985, -4.176
>
> ??? >>> M2?????? 47.400, 74.685, -1.686
>
> ??? >>>?
>
> ????>>> You can see that the UV radiation from the spectro in M2 mode is
> passing through the magenta ink and the secondary blue radiation is coming
> back to the sensor.
>
> ??? >>>?
>
> ????>>> But with the yellow ink, you cannot see any trace of the UV and
> the blues (whether reflected or induced). In fact, the yellow ink doing
> what it is supposed to do.
>
> ??? >>>?
>
> ????>>> With cyan the results are intriguing to say the least:
>
> ??? >>>?
>
> ????>>> #576 C=100 | M=0 | Y=0 | K=0
>
> ??? >>> M0?????? 52.341, -35.091, -53.202
>
> ??? >>> M1?????? 52.675, -34.902, -53.720
>
> ??? >>> M2?????? 52.580, -36.430, -52.034
>
> ??? >>>?
>
> ????>>> Seeing the limited or no effect of the UV induced blue light in
> the solid cyan measurement, I am tempted to say that cyan, being the narrow
> band filter that it is, has been blocking the UV coming from the spectro.
>
> ??? >>>?
>
> ????>>> Simultaneous M0, M1 and M2 measurements of substrates with OBAs
> indicate that M0 and M1 results are closer to each then they are to M2
> results. Apparently, the M0 illuminant contains some OBA triggering
> radiation. May be we should use M2 for a subtrate-free judgement of the ink
> film color/neutrality and use M1 for registering the visual appearance. The
> spectro is, in a way acting like the human eye, in M1 mode. And may be we
> should use an M2-based profile in relative colorimetric (with BPC) or
> perceptual mode for seperation/conversion and an M1-based profile for
> proofing in absolute colorimetric mode.
>
> ??? >>>?
>
> ????>>> I am not the color scientist to understand how an M1 mode
> measurement set is stripped off the substrate color to serve as a base for
> a relative colorimetric conversion, but I am the engineer who can say that
> something I wrong in the way data for yellow channel is now being handled.
> What has been working for 10+ years with FOGRA39 is now broken, to say the
> least.
>
> ??? >>>?
>
> ????>>> Best regards,
>
> ??? >>>?
>
> ????>>> --------------------------------------------------------
>
> ??? >>> Refik Telhan, EE B.Sc.
>
> ??? >>>?
>
> ????>>> Light and Color Management Consultancy
>
> ??? >>>?
>
> ????>>> Aydogdu Sokak 12A, Tarabya Mahallesi
>
> ??? >>> Sariyer, 34457, Istanbul, Turkey
>
> ??? >>>?
>
> ????>>> Mobile: + (90) (532) 426 21 87
>
> ??? >>> --------------------------------------------------------
>
> ??? >>>?
>
> ????>>> ?On 19.02.2019 01:29, "florian(a)suessl.de" <
> eci-en-bounces(a)lists.callassoftware.com on behalf of florian(a)suessl.de>
> wrote:
>
> ??? >>>?
>
> ????>>>???? Dear Refik and al,
>
> ??? >>>????
>
> ????>>>???? nothing to add at that point to your understandable surprising
> findings about yellow decrease.
>
> ??? >>>????
>
> ????>>>???? Regarding your test starting with ?10 LAB GRAY.psd?:
>
> ??? >>>???? > Starting with your ?10 LAB GRAY.psd? file, I first did a
> RelCol+BPC conversion into ISO Coated v2 (ECI), then assigned PSO coated
> v3.
>
> ????>>>???? in your scenario the tone values of the conversion to the
> ?ISO:2003? tvi curve are ?printed? with the ?ISO:2013? curves. The
> differences may be not very high, but in order to properly compare the ?v2?
> gray reproduction with the current ?v3? reproduction we should take the tvi
> differences between the 2003 and 2013 tvi curves into account.
>
> ????>>>????
>
> ????>>>???? Please feel free to check the files in this dropbox:
>
> ??? >>>????
> https://www.dropbox.com/s/8kt2kwe1w0vthwj/Gray-comparison_PSOcoated-v3_vers…
>
> ??? >>>????
>
> ????>>>???? Before reassigning ?PSO Coated v3? to a RelCol+BPC conversion
> into ISO Coated v2 (ECI), I applied a tvi correction. Just like in a CtP
> system correcting a dot gain deviation on the press. The correction values
> are stored in the file ?pdfTB_005_F39_but_F51-tvi.crv? (tv correction done
> in the callas PDFToolbox).
>
> ??? >>>????
>
> ????>>>???? The result is placed next to the RelCol+BPC conversion into
> PSO Coated v3. The respective file ?24 Lab Gray relcol+bpc F39 > tvi corr
> F51 vs F51? contains both gray reproductions side by side. Switching on
> paper simulation in Acrobat Pro and viewing in full screen mode (all bars
> and windows hidden), shows a good softproof rendering of the expected
> printing result.
>
> ??? >>>????
>
> ????>>>???? As mentioned earlier also by Jan-Peter Homann, the ?v3?
> profile?s linear gradient from paper (here a=2, b=-6) to neutral (a=b=0) is
> perceived slightly (too) cold.
>
> ??? >>>????
>
> ????>>>???? All the best
>
> ??? >>>???? Florian
>
> ??? >>>????
>
> ????>>>???? > Am 18.02.2019 um 22:27 schrieb Refik Telhan <
> rtelhan(a)ofset.com>:
>
> ??? >>>???? >
>
> ????>>>???? > Dear Florian,
>
> ??? >>>???? >?
>
> ????>>>???? > I have two hats. First of all, I am a prepress guy. But I am
> also a printer. On this occasion, I am letting the printer do most of the
> talking. For more than 10 years printers have relied on FOGRA39 (and to a
> lesser extent on FOGRA47). And they have learnt to cope with the paper
> white issue of both datasets. The separations had a full body yellow
> channel which they could use to compensate for the daily differences in the
> paper white of typically used papers. A solid ink density of 1.30 (ISO E ?
> Relative to paper ? polarised) for Yellow was a good starting point, from
> which they could manage both the dot gain of the day issues as well as the
> paper white differences. They could solve many of the daily problems within
> the 1.10 to 1.50 density range.
>
> ??? >>>???? >?
>
> ????>>>???? > Currently, we are printing on the same paper with
> technically the same SIDs for all colors, with the same balance between
> C-M-Y channels, but we are now told that we have to print a lesser amount
> of yellow. The old profiles were OK from the stand point of the printer.
> The only real issue was the yellowish paper white of the proofs. That was
> the only thing that needed a fix. Yellow is the carrier of varnish. Varnish
> brings gloss, rub resistance and a certain visual depth to black. These are
> mostly gone. The old profiles were separating to a paper white of 95, 0, -2
> and were doing fine on the real papers. Now the profiles are aware of the
> real paper whites that are loaded with OBAs but they offer us less yellow
> than before.
>
> ??? >>>???? >?
>
> ????>>>???? > The leverage yellow was providing is gone. And with FOGRA52
> it is even worse. With a high GCR variant of FOGRA52 that I generated
> today, I ended up with a separation of C=100, M=52, Y=3 (yes, it is three)
> and K=92 at the dark end. With the relatively neutral imaginary paper of
> the past, we had sufficient yellow to play around. And the bluer the real
> paper is getting the lesser yellow is what we are having. This phenomenon
> needs a good explanation.
>
> ??? >>>???? >?
>
> ????>>>???? > Starting with your ?10 LAB GRAY.psd? file, I first did a
> RelCol+BPC conversion into ISO Coated v2 (ECI), then assigned PSO coated
> v3. Finally, I did an absolute colorimetric conversion back to Lab. I will
> be uploading the file my Dropbox folder under the name ?16 LAB GRAY ?..?.
> This is closer to what I need to see. You will also find files with names
> starting with 17 and 18. Those are the FOGRA47 and FOGRA52 conversions.
> Where the FOGRA47 separation is neeeding more yellow to appear natural to
> many eyes, the FOGRA52 is offering less.
>
> ??? >>>???? >?
>
> ????>>>???? > Paper relative neutrality will always be somewhat
> subjective. In both FOGRA51 and 52 worlds, profiles that did gray axis
> correction in perceptual conversions midway between a paper relative gray
> and an absolute gray, are giving more pleasing results. This, paper
> relative neutral gray versus absolute neutral gray issue was with us even
> in the old days, especially with the FOGRA47 dataset. We now need it
> everywhere.
>
> ??? >>>???? >?
>
> ????>>>???? > Best,
>
> ??? >>>???? >?
>
> ????>>>???? > --------------------------------------------------------
>
> ??? >>>???? > Refik Telhan, EE B.Sc.
>
> ??? >>>???? >?
>
> ????>>>???? > Light and Color Management Consultancy
>
> ??? >>>???? >?
>
> ????>>>???? > Aydogdu Sokak 12A, Tarabya Mahallesi
>
> ??? >>>???? > Sariyer, 34457, Istanbul, Turkey
>
> ??? >>>???? >?
>
> ????>>>???? > Mobile: + (90) (532) 426 21 87
>
> ??? >>>???? > --------------------------------------------------------
>
> ??? >>>???? >?
>
> ????>>>???? >?
>
> ????>>>???? > ?On 16.02.2019 20:47, "florian(a)suessl.de" <
> eci-en-bounces(a)lists.callassoftware.com on behalf of florian(a)suessl.de>
> wrote:
>
> ??? >>>???? >?
>
> ????>>>???? >???? Dear Refik,
>
> ??? >>>???? >????
>
> ????>>>???? >???? To test whether or not the yellow reduction causes
> problems or is meaningfull, I did another test, you may wish to reproduce:
>
> ??? >>>???? >????
>
> ????>>>???? >???? - Create a linear gradient from black (LAB 0-0-9) to
> white (LAB 100-0-0)
>
> ????>>>???? >???? - convert to the two profiles ?v2-300? and ?v3?
> (relative colorimetric, black point compensation ON)
>
> ??? >>>???? >???? - convert the results back to Lab (absolute colorimetric)
>
> ??? >>>???? >???? - check the b values along the gradient from black to
> white:
>
> ??? >>>???? >????
>
> ????>>>???? >???? The v3 version will start with b 0 (neutral) and will
> run smoothly to b -6 (paper tone)
>
> ??? >>>???? >???? This is the intended behaviour
>
> ??? >>>???? >???? And in order to achieve this, obviously yellow needs to
> be reduced in dark grays ? otherwise, the gray would be too warm/yellowish
>
> ??? >>>???? >????
>
> ????>>>???? >???? In other words: the behaviour (cmy percentages) is not
> expected and therefore misinterpreted as an error.
>
> ??? >>>???? >????
>
> ????>>>?? ??>???? This in mind, I would rate the separation behaviour to
> be ok.
>
> ??? >>>???? >????
>
> ????>>>???? >???? For your and other interested parties convenience, I
> uploaded my test files for testing here:
>
> ??? >>>???? >????
> https://www.dropbox.com/s/l1jbob7uemuxxiw/190215%20ECI-EN%20Refik%20yellow%…
>
> ??? >>>???? >????
>
> ????>>>???? >???? All the best
>
> ??? >>>???? >???? Florian
>
> ??? >>>???? >????
>
> ????>>>???? >???? > Am 15.02.2019 um 23:14 schrieb florian(a)suessl.de:
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > Dear Refik,
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > Your finding is, that FOGRA39, PSO Coated v2
> separations show warmer grays (more yellow) on ?FOGRA51? stock than FOGRA51
> separartions printed on the same stock ? each set printed with their
> respective tvi curves ? right?
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > As we agreed on a very good proof to print match of
> FOGRA51, the following test may be used to compare the visual gray
> reproductions of PSO Coated v3 (?v3?) and ISO Coated v2 300% (?v2?):
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > Assumptions and setup:
>
> ??? >>>???? >???? > - both gray reproductions ?v2? and ?v3? printed on
> ?PSO Coated v3? stock (CIELAB 95 2 -6; M1)
>
> ??? >>>???? >???? > - identical CIELab of ink solids for ?2v? and ?v3?
> (FOGRA51 values)
>
> ??? >>>???? >???? > - each set printed with respective tvi (v2 with
> tvi:2003; v3 with tvi:2013)
>
> ??? >>>???? >???? > - the visual appearance depends on the cmyk tone
> values *measured on print* only.? Lower cmyk values in the file plus higher
> tvi in print (?v3?) may result in the same *printed* cmyk tone values as
> higher cmyk values in the file plus lower tvi (?v2?).
>
> ??? >>>???? >???? > - to achieve the same *printed* tone values for a v3
> soft proof, the v2-values must be tone value corrected according to the v3
> tone value increase
>
> ??? >>>???? >???? > - use of PSO Coated v3, FOGRA51 respectively for
> calculating the CIELab values of the two gray reproductions
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > step 1: calculate *printed* cmyk values for ?v2?
>
> ??? >>>???? >???? > ?print-cmyk v2? (v2-file-cmyk + tvi:3003)????? ??????
>
> ????>>>???? >???? > C?????????????? M????????????????????
> Y????????????????????? K
>
> ??? >>>???? >???? > 38,2?????????????????????? 29???????????????????
> 30,3???????????????? 11
>
> ??? >>>???? >???? > 59,9?????????????????????? 50,6???????????????? 49,4
> ????????????????45
>
> ??? >>>???? >???? > 76,4?????????????????????? 66,5????????????????
> 64,3???????????????? 79,3
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > step 2: calculate v3 file-values to achieve the
> printed values of step 1 (v2-file-values + 2003-tvi - 2013-tvi)
>
> ??? >>>???? >???? > ?file-cmyk v2>v3? (v2-file-cmyk + tvi:2003 - 2013-tvi)
>
> ??? >>>???? >???? > C?????????????? M????????????????????
> Y????????????????????? K
>
> ??? >>>???? >???? > 25,8????????????????????? 18,9????????????????
> 19?????????????????? ?6,7
>
> ??? >>>???? >???? > 44,2????????????????????? 36,9????????????????
> 34,9???????????????? 31,2
>
> ??? >>>???? >???? > 60,9?????????????????????? 50,5????????????????
> 48,3???????????????? 64,2
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > step 3: create CIELab values; visual appearance of the
> two gray sets ?file-cmyk v3? and ?file-cmyk v2>v3?
>
> ??? >>>???? >???? > absolute colorimetric conversion from file-cmyk to PSO
> Coated v3
>
> ??? >>>???? >???? > ?file-cmyk v3?
>
> ??? >>>???? >???? > L??? a????????? b
>
> ??? >>>???? >? ???> 72? 1????????? -5
>
> ??? >>>???? >???? > 49? 1????????? -4
>
> ??? >>>???? >???? > 28? 1????????? -2
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > ?file-cmyk v2>v3?
>
> ??? >>>???? >???? > L??? a????????? b
>
> ??? >>>???? >???? > 72? 1????????? -4
>
> ??? >>>???? >???? > 49? 1????????? -2
>
> ??? >>>???? >???? > 27? 0????????? -1
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > step 4: visual comparison
>
> ??? >>>???? >???? > visual differences (Lab?v3? - Lab?v2>v3?)
>
> ??? >>>???? >???? > ?L? ?a??????? ?b
>
> ??? >>>???? >??? > 0??? 0????????? -1
>
> ??? >>>???? >???? > 0??? 0????????? -2
>
> ??? >>>???? >???? > 1??? 1????????? -1
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > The negative ?b numbers mean, that relative
> colorimetric colour conversions with black point compensation using ?PSO
> Coated v3? print slightly more blueish grays than the ?ISO Coated v2 300%?
> values.
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > Comparing the file-cmky-values gives these results:
>
> ??? >>>???? >???? >
>
> ????>>>???? >??? ?> ?file-cmyk v2>v3? (v2-file-cmyk + tvi:2003 - 2013-tvi)
>
> ??? >>>???? >???? > C?????????????? M????????????????????
> Y????????????????????? K
>
> ??? >>>???? >???? > 25,8????????????????????? 18,9????????????????
> 19??????????????????? 6,7
>
> ??? >>>???? >???? > 44,2????????????????????? 36,9????????????????
> 34,9???????????????? 31,2
>
> ??? >>>???? >???? > 60,9?????????????????????? 50,5????????????????
> 48,3???????????????? 64,2
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > ?file-cmyk v3?
>
> ??? >>>???? >???? > C????????????? ?M????????????????????
> Y????????????????????? K
>
> ??? >>>???? >???? > 27????????????? 21???????????????????
> 20??????????????????? 5
>
> ??? >>>???? >???? > 46????????????? 38???????????????????
> 35??????????????????? 28
>
> ??? >>>???? >???? > 61????????????? 51???????????????????
> 44??????????????????? 63
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > tv differences *file-tv* (v3 - v2 converted; tvi:2013)
>
> ??? >>>???? >???? > ?C???????????? ?M?????????????????
> ?Y??????????????????? ?K
>
> ??? >>>???? >???? > 1,2???????????? 2,1??????????????????
> 1,0?????????????????? -1,7
>
> ??? >>>???? >???? > 1,8???????????? 1,1??????????????????
> 0,1?????????????????? -3,2
>
> ??? >>>???? >???? > 0,1???????????? 0,5??????????????????
> -4,3????????????????? -1,2
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > Higher cmy and lower k values are caused by different
> black settings
>
> ??? >>>???? >???? > The negative tone value difference (-4,3) prooves your
> finding of ?PSO Coatec v3??s higher reduction of yellow in dark gray areas.
>
> ????>>>???? >???? >
>
> ????>>>???? >???? > However ? in my personal experience I did not see the
> kind of blueish turn in grays yet.
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > The test was done in Photoshop. Due to rounding
> effects the result is not as accurate as it might be, but should be valid.
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? > All the best
>
> ??? >>>???? >???? > Florian
>
> ??? >>>???? >???? >
>
> ????>>>???? >???? >> Am 15.02.2019 um 13:03 schrieb florian(a)suessl.de:
>
> ??? >>>???? >???? >>
>
> ????>>>???? > ????>> Dear Refik,
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> Similar situation at my end:)
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> Quick answer first:
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> Comparing the two, I would recommend to choose
> profiles with the same TAC setting.
>
> ????>>>???? >???? >> As a quick test, reproducing your test with ISO
> Coated v2 300%, the comparison of F39 and F51 shows a different picture:
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> ISO Coated v2 (ECI) ? your figures:
>
> ??? >>>???? >???? >> C=29, M=22, Y=22, K=06
>
> ??? >>>???? >???? >> C=49, M=40, Y=40, K=27
>
> ??? >>>???? >???? >> C=67, M=57, Y=55, K=58
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> ISO Coated v2 300% (ECI)
>
> ??? >>>???? >???? >> C=28, M=21, Y=22, K=07
>
> ??? >>>???? >???? >> C=46, M=38, Y=37, K=31
>
> ??? >>>???? >???? >> C=62, M=52, Y=50, K=63
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> PSO Coated v3
>
> ??? >>>???? >???? >> C=27, M=21, Y=20, K=05
>
> ??? >>>???? >???? >> C=46, M=38, Y=35, K=28
>
> ??? >>>???? >???? >> C=61, M=51, Y=44, K=63
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >>
>
> ????>>>???? >???? >> Long answer ? comparison of separation values (cmyk
> file):
>
> ??? >>>???? >???? >> We talk about differences of some percentages. As v2
> and v3 are based on different tone value curves, I would prefer to take
> into account the tvi differences. We talk about differences of some
> percentages. You rised the tvi difference already. In addition to that, the
> curve shapes are not the same for v2 and v3. As cyan tv is higher than
> yellow and magenta, this has some impact.
>
> ????>>>???? >???? >> I.o.w. a comparison of tone values should NOT be
> based on values in the cmyk files only. We should add the tvi dot gain to
> the separation tone value first. As soon as I find the time for this I will
> prepare the numbers and come back then.
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> Another aspect is the Lab result ? quick check by
> absolute colorimetric conversion back to Lab:
>
> ??? >>>???? >???? >>
>
> ????>>>? ???>???? >> ISO Coated v2 300% (ECI)
>
> ??? >>>???? >???? >> L=72, a=0, b=-2
>
> ??? >>>???? >???? >> L=49, a=0, b=-1
>
> ??? >>>???? >???? >> L=27, a=0, b=-1
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> PSO Coated v3
>
> ??? >>>???? >???? >> L=72, a=1, b=-5
>
> ??? >>>???? >???? >> L=49, a=1, b=-4
>
> ??? >>>???? >???? >> L=28, a=1, b=-2
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> As expected, the gray Lab values make sense, if gray
> is based on the paper tones 95 0 -2, 95 2 -6, respectively.
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >>
>
> ????>>>???? >???? >> All the best for now.
>
> ??? >>>???? >???? >> Florian
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >>
>
> ????>>>???? >???? >>
>
> ????>>>???? >???? >>
>
> ????>>>???? >???? >>> Am 15.02.2019 um 11:38 schrieb Refik Telhan <
> rtelhan(a)icloud.com>:
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Dear Florian,
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Daily consulting work and a computer breakdown has
> kept me from responding earlier.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> FOGRA51 and FOGRA52 proofs:
>
> ??? >>>???? >???? >>> I agree with the premise that FOGRA51 and FOGRA52
> proofs are a closer match to the real thing (apart from the very dark end
> of the shadows, which somewhat hides the inherent purplishness). The real
> problem is the conversions/separations made by these profiles. They strip
> away a good portion of the yellow channel. And the proofs do a very
> realistic simulation of this lack of yellow.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> FOGRA39/FOGRA47 proofs are unrealistically yellowish
> but the real printing comes out in a more naturally neutral appearance.
> Hence, we should focus on the way RGB-to-CMYK conversions are being made.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> TAC 300
>
> ??? >>>???? >???? >>> Comparing the darkest points of FOGRA39 and
> FOGRA51-based profiles, I can say that the decision to limit TAC at 300%
> has casused a 3 step increase in the L* value of dark end. The Maximum
> Black of ISO Coated v2 (ECI) is (9,0,2) whereas PSO Coated v3 can only do
> (12,0,5). This quite a loss and is probably related with the 300% TAC.
> Latest high reactive UV inks are making TAC values even higher than 330%
> possible. But to make color management useable by many, you have decided to
> limit the TAC, as it suits conventional oil-based inks more. And, as you
> said, experts are free to improvise with higher TACs anyway.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Grey Reproduction:
>
> ??? >>>???? >???? >>> This is the most problematic part of the issue at
> hand. Even in the FOGRA39 world, no neutral grey is really ?neutral? in the
> colorimetric sense of the word. It is all ?relative to paper?. A FOGRA39,
> or even a FOGRA47, separation prints with a natural/neutral grey appearance
> on its own paper.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Let us concentrate on an image that only contains
> three grey steps:
>
> ??? >>>???? >??? >>>
>
> ????>>>???? >???? >>> Step 1) L*=75, a*=0, b*=0
>
> ??? >>>???? >???? >>> Step 2) L*=50, a*=0, b*=0
>
> ??? >>>???? >???? >>> Step 3) L*=25, a*=0, b*=0
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> In the ISO Coated v2 (ECI) colorspace these would
> separate into CMYK (under the relative colorimetric rendering intent with
> black point compensation) as,
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> C=29, M=22, Y=22, K=06
>
> ??? >>>???? >???? >>> C=49, M=40, Y=40, K=27
>
> ??? >>>???? >???? >>> C=67, M=57, Y=55, K=58
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> When proofed in a FOGRA39-certified way, these greys
> definitely appear yellowish. But when they are printed on a commercially
> available matt coated paper, with a white point of L*=96.0, a*=1.0, b*=-4.6
> (MO) --- L*=96.0, a*=1.3, b*=-6.2 (M1) under a C-M-Y dot gain of 14.3% at
> mid-tones with the ISO CMYK primaries, we end up with perfectly acceptable
> naturally neutral appearance.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Then we switch to the FOGRA51 world; the matt coated
> paper is the same, CMYK primaries -in terms paper relative ISO E
> (polarized) density values- are almost the same, C-M-Y dot gains are just
> 1.7% higher than the old system but equal (16%) to each other. However,
> with the PSO Coated v3 separation, we end up with,
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> C=27, M=21, Y=20, K=05
>
> ??? >>>???? >???? >>> C=46, M=38, Y=35, K=28
>
> ??? >>>???? >???? >>> C=61, M=51, Y=44, K=63
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> You can clearly see that the dot percentages of Cyan
> and Magenta have dropped by about 2% which is clearly related with the dot
> gain curve rising from 14.3% to 16%. The Black percentage has risen up by
> 1%, which is in line with the dot gain going down to 16% from 17%. Up to
> this this point everything is understandable and accountable.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> From this point on I feel somewhat lost. The yellow
> channel is bleeding off the charts with no apparent reason. With darker
> shades of grey, the gap between Magenta and Yellow gets even bigger. At
> L*=5, a*=0, b*=0 the CMYK conversion is C=75, M=63, Y=50, K=89.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Technically speaking, under both printing
> conditions, the papers are the same, inks are the same, ink film
> thicknesses are the same, ink coverages for C, M and K are the same. Why
> are we losing the yellow channel?
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> And with FOGRA52, it is pretty much the same story.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> To carry over the current balance of the C-M-Y
> separations of the FOGRA39 world into FOGRA51, I have started
> playing/experimenting with the white points of the datasets. I first
> separated a neutral image into ISO Coated v2 (ECI), assigned PSO Coated v3
> to the file and then proofed it in a FOGRA51-verified workflow. As I had
> eplained in my previous mail, this gave me a neutral looking proof. The ISO
> Coated v2 (ECI) separation and the FOGRA39-certified proof of the same
> eciRGBv2 image have a yellowish cast as expected. And the FOGRA51
> separation and the FOGRA51-certified proof is on the pinkish/purplish side.
> I hope to run a print test next week that includes both FOGRA51 tagged
> images receiving ink from the same ink keys. As we have already said, the
> FOGRA51-certified proofs are realistic simulations of the actual print.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> To get rid of the paper color all together, so that
> it does not interfere with the conversion process in any way or form, in
> the hope of getting a neutral C-M-Y ink film build up, I have modified the
> white point of the FOGRA51 dataset to 95, 0, 0. We have been using
> imaginary papers for conversions for a very long time. May be the success
> of FOGRA39 and FOGRA47 was in their synthetic paper whites which are very
> close to a*=b*=0.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> I did the editing with ColorLogic?s ColorAnt v5.1.
> After the editing I have also previewed the profiling chart in 2D mode, to
> see that all patches have been stripped of the the base paper color. While
> checking this new dataset in ColorAnt and later on in CoPrA v4, I have seen
> that the profile would go on to be build the with same yellow deficiency.
> For some reason, the measurement data was carrying too much yellow.
> Consequently, the profiling application is trying too suppress the yellow
> to generate a netural grey ink film in the relative colorimetric mode. As I
> have discussed recently, the printing conditions of FOGRA39 and FOGRA51 are
> very much in parallel. Hence, the balance between C-M-Y channels should in
> fact be the same. But they are not acting in the expected way. The only
> real difference betwwen the two is the way we are measuring the profiling
> charts, namely M0 versus M1.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Being an old hand who has lived through the times
> where Rapid Access films were exposed in UV contact frames in ?dark rooms?
> illuminated with fluorescent lamps that had yellow sleeves. Those sleeves
> were there to block out the UV radiation of the T8 tubes. In short, yellow
> filter blocks UV. And for this very reason, yellow ink is UV-killer. Just
> try imagining how a spectrophotometer, with its 45?/0? geometry, is sending
> the illumination to the measured sample. In M1 measurement mode, the
> unobstructed UV ligh,t that is now part of the illumination, easily reaches
> the unprinted paper. Hence, OBA is triggered to create the secondary
> radiation that is centered around 430 nanometers. We then measure this as a
> lower b* value. With a moderate amount of OBA, the b* value typically moves
> from -4.5 to -6. Now let us print yellow ink on this paper. When you
> measure a patch which contains a heavy dose of yellow ink, the UV
> illuminant of the spectrophotometer never r
> eaches the paper. The higher the dot percent of yellow ink, higher is the
> filtering effect. Hence, areas covered with yellow ink will never release
> the secondary blue radiation. But the software, most probably, thinking
> that it is there, and based on the ?normal? level of b* value, is assuming
> that an extra amount yellow has been used to neutralizing this blue
> component. Consequently, the software, while doing a relative conversion,
> is stripping off the supposedly ?extra? yellow from the separation. Just do
> an absolute colorimetric conversion and see how much yellow ii added to the
> yellow channel to counter the bluness of the paper. And the suppression
> grows as the coverage/thickness of yellow ink increases. The more you have
> the yellow ink, the more it blocks the UV LED of the spectro.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Under these circumstaces, I would say that M1
> measurement mode has created more problems than it was designed to solve.
> While it may be a handy tool to see the amount of OBA contained in the
> print substrate, it is simply misleading when yellow ink is around. Just do
> a series of measurements at the same spot without moving the spectro in M0,
> M1 and M2 modes, you will have very healty indication of the existence and
> the amount of OBA. But let us not forget yellow filters are UV-killers. And
> yellow ink is a yellow filter.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Having graduated as an electrical engineer 42 years
> ago, I have lived through the heyday of fluroscent lamps but I always hated
> the rate at which the blue output decays. The T8 tubes being rated at 20000
> hours for daily use can only last 2500 hours as a reference. After that,
> they are only for good for general illumination. And now LED light sources
> are becoming full-spectrum illuminants, and some have reached very high CRI
> values (98+) at 5000?K. There manufackurers are now desparately trying to
> mix and match them UV chips to reach ISO 3664:2009 compatibility.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Fluorescent lamps are on their way out, leaving the
> general public with no source of UV other than the Sun itself. And nobody
> would be reading a book in full color under the Sun. Hence, the paper
> industry has to reconsider the way they are using OBAs now. LED light
> sources, even the full-spectrum white LEDs, do not contain any UV. They
> ususally cut emission atf 410 ? 420 nanometers. White LEDs are typically
> triggered with a blue emitting diode evidenced by the peak at 410
> nanometers. I have not made any testing to see which wavelengths actually
> trigger the OBAs, I would leave this to good scientists. But apparently, we
> should get ready for a UV-free and OBA-free eco system, where we would not
> need to use the M1 measuring mode. In some years time, the illumination for
> the public will become UV-free. It is high time that we start getting rid
> of UV (as illuminant) related technologies and problems. As an ink-curing
> tool, I believe that it will become indisp
> ensible.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Many of what I said is just hypothesis. I believe
> there very good color scientists who can take over and do the rest.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Looking forward to hearing from my colleagues, I
> remain.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Best regards,
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>
> --------------------------------------------------------
>
> ??? >>>???? >???? >>> Refik Telhan, EE B.Sc.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Light and Color Management Consultancy
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Aydogdu Sokak 12A, Tarabya Mahallesi
>
> ??? >>>???? >???? >>> Sariyer, 34457, Istanbul, Turkey
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> Mobile: + (90) (532) 426 21 87
>
> ??? >>>???? >???? >>> e-Mail: rtelhan(a)icloud.com
>
> ??? >>>???? >???? >>>
> --------------------------------------------------------
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> P.S. Just to find a short term solution to the
> problem, I have modified the FOGRA39L dataset to bring it along side the
> PC1 printing condition. Using ColorAnt v5, I have modified the white point
> to 95, 1.5, -6 (which is in fact an M1 measurement, but perhaps I should
> have used the M0 value of the same paper, namely 96, 1, -4.5). I have then
> edited the tone values to ISO 2013 Curve A. The profile (TAC: 330%)
> generated out of this heavily modified dataset is acting in much the way
> that I expected:
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> (RelCol w/BPC conversion)
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> L*=75, a*=0, b*=0 ----> C=27, M=19, Y=20, K=06
>
> ??? >>>???? >???? >>> L*=50, a*=0, b*=0 ----> C=42, M=32, Y=33, K=36
>
> ??? >>>???? >???? >>> L*=25, a*=0, b*=0 ----> C=52, M=42, Y=40, K=72
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> I will be first doing some image conversions and
> FOGRA51-verified/certified proofing to see how naturally looking CMYK files
> I am getting. And then I will do a machine test to see how close I can get
> to the proofs. I will definitely share the results.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> -----------------------------
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> ?On 12.02.2019 14:29, "florian(a)suessl.de" <
> eci-en-bounces(a)lists.callassoftware.com on behalf of florian(a)suessl.de>
> wrote:
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>?? Dear Rafik,
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>?? Thanks again for your valuable posts.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>?? Regarding your findings about FOGRA51 and FOGRA52
> proofs:
>
> ??? >>>???? >???? >>>?? Comparing with FOGRA39 proofs, which tend to show
> warmer colours I agree. And I can imagine that ?cooler? F51 and F52? proofs
> are confusing for clients who are familiar with ?warmer? FOGRA39 proofs.
> BUT:
>
> ??? >>>???? >???? >>>?? As Claas already mentioned, the proof to print
> match is by far better with FOGRA51 and FOGRA52 under proper lighting
> conditions (with proper UV content; ISO3664:2009). Especially regarding
> light colours and paper simulation which was by far too yellowish/warm in
> F39/ F47 proofs compared to standard compliant printing on todays papers.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>?? TAC 300
>
> ??? >>>???? >???? >>>?? The reason for reducing TAC to 300 and not to
> offer two flavours as for FOGRA39: In general, TAC 300% work well with
> regard to the visual result. More than 300% in some cases (paper dependant)
> may cause production issues. Second reason: Providing one profile makes it
> easier for the non skilled users to choose the right profile per paper
> type. This to reflect one of the main goals of the ECI: Making colour
> management easier to use.
>
> ??? >>>???? >???? >>>?? Of course experts are free to create and use
> profilles with other TAC and separation settings, as they have to tools and
> expertise.
>
> ????>>>???? >???? >>>?? For these reasons, we (ECI) decided to provide
> only one profile with TAC 300%.
>
> ????>>>???? >???? >>>
>
> ????>>>???? >???? >>>?? Grey reproduction:
>
> ??? >>>???? >???? >>>?? This topic is very tricky and cannot be solved
> perfectly with a single profile, a single grey reproduction respectively.
> The chromatic white point adaptation of our colour perception depends on
> the given white reference when we look at the print. This reference changes
> from situation to situation. In many cases, the paper white is a good
> choice, given, there is nothing else viewed influencing the white
> adadaption to the paper, and given, the illumination is perceived ?white?.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>?? As soon as more than one reference white is viewed
> simultaneously, it becomes difficult. For example in magazine production,
> with different stock for cover and content. In case of an ad which is split
> in two halfs, one printed on the cover paper (coated, OBA content), the
> other half printed on SC paper (low to no OBA).
>
> ????>>>???? >???? >>>?? Each part colour separated with the respective
> profile, may show different grey reproductions which work well if viewed
> exclusively ? but may not if viewed simultaneously.
>
> ????>>>???? >???? >>>?? I.o.w.: When creating the profiles, it is not
> possible to take into account all variables influencing the grey
> perception. There is no digital right or wrong.
>
> ??? >>>???? >???? >>>?? If problems e.g. in above mentioned situations
> (one product, different papers) occure, editing the grey axis will be
> depend on a case by case decision ? as you already mentioned.? ?Standard?
> profiles can provide one grey reproduction which may or may not work in a
> given situation.
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>
>
> ????>>>???? >???? >>>?? Best Regards
>
> ??? >>>???? >???? >>>?? Florian S??l
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>> Am 12.02.2019 um 01:14 schrieb Refik Telhan <
> rtelhan(a)ofset.com>:
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> Dear Florian,
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> I agree, yellow can add very little to the
> darkening of the L* value of the shadows. But, due to the optical and
> physical qualities of the varnish that it contains, yellow ink adds to the
> blackness ?visually?. You may not be able to ?measure? it but you can
> definitely ?see? it. The gloss effect of this ink definitely add to the
> apparent blackness of the shadows. It is no wonder that the computer
> display and tv manufacturer are usin using very glossy panels to increase
> the apparent dynamic range of the monitor. Any mattness casuses surface
> scatter and reduces visual darkness. Furthermore, the yellow ink also
> physically protects the printed image against rub resistance.
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> As TAC has been reduced down to 300% in FOGRA51 as
> opposed to its value of 330% in FOGRA39, yellow loses additional strength.
> We end up with bluish cold blacks which may prove to be problematic in
> printing art books. In some cases the artwork may call for a dark reddish
> or a brownish shadow. But the current profiles are making it very hard to
> get there. You need to heavily modify the RGB shadows before the conversion
> to CMYK.
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> And this only one side of the story. As the new
> datasets (both FOGRA51 and FOGRA52) are based on ?real? papers, the
> paper-relative greys of the relative colorimetric (with BPC) and the
> perceptual rendering intent conversions are leaving much to be desired. The
> paper-relative neutrals rely too much on the chromatic adaptation
> capability of the eye. The paper-white-simulated proofs move away from the
> balanced appearance of the RGB (any RGB) version. Color ToolBox is equipped
> with the Keep Grey Axis functionality (which you can adjust from
> paper-relative grey to absolute-netural grey in 10 steps) that allows you
> to compensate for the paper color in the perceptual rendering intent
> conversions.
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> Best regards,
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> Refik Telhan, EE B.Sc.
>
> ??? >>>???? >???? >>>> Light and Color Management Consultancy
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> From: <eci-en-bounces(a)lists.callassoftware.com> on
> behalf of Florian S??l <florian(a)suessl.de>
>
> ??? >>>???? >???? >>>> Reply-To: <eci-en(a)lists.callassoftware.com>
>
> ??? >>>???? >???? >>>> Date: 11 February 2019 Monday 20:19
>
> ??? >>>???? >???? >>>> To: <eci-en(a)lists.callassoftware.com>
>
> ??? >>>???? >???? >>>> Subject: Re: [ECI-EN] Issues related with the
> switch from FOGRA39/47 to FOGRA51/52
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> Dear Refik,
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> Thank very much for your extensive testing and the
> documentation of your findings.
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> With regard to dark grey tones, the decrease of
> yellow tone values is intended as the the following may explain:
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> According to the standard printing ink sequence,
> yellow is the last ink (kcmy sequence).
>
> ??? >>>???? >???? >>>> The expected effect of raising ink tone values is
> that higher values cause darker colour.
>
> ??? >>>???? >???? >>>> But this is not true.
>
> ??? >>>???? >???? >>>> Printed on top of the other inks, the yellow ink
> tends to behave like a mirror, reflecting light. In order to avoid this
> effect, yellow is limited in dark grey tones.
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> Hope this helps.
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> Best Regards
>
> ??? >>>???? >???? >>>> Florian S??l
>
> ??? >>>???? >???? >>>> Vice chairman of the ECI
>
> ??? >>>???? >???? >>>> --
>
> ??? >>>???? >???? >>>> Florian S??l
>
> ??? >>>???? >???? >>>> Go?lerstra?e 29
>
> ??? >>>???? >???? >>>> 12161 Berlin
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>> Am 11.02.2019 um 09:47 schrieb Refik Telhan <
> rtelhan(a)ofset.com>:
>
> ??? >>>???? >???? >>>>
>
> ????>>>???? >???? >>>>> Dear Colleagues,
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> It all started with a question raised by Mr.
> Martin Orpen in his mail dated 22.08.2018 on the colorsync-users list.
> There was then almost a week long discussion with an open end.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> From that point on, I have made several
> conversions using FOGRA39, FOGRA47, FOGRA51 and FOGRA52 based profiles. At
> some point I have started generating profiles with the FOGRA51 and FOGRA52
> datasets in multiple profiling software applications with different
> settings to have a better understanding on what is going on.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Mr. Orpen?s original complaint was the lack of
> yellow in skin tones with conversions made with PSO Coated v3. But when I
> started doing conversions using this profile, I have ended seeing that that
> deficiency ih yellow is widespread. Furthermore, what was true for FOGRA51
> was also true for FOGRA52-based profiles.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> To simplify the matter, I have created a Photoshop
> file in L*a*b* color mode that contained a linear gradient from L*=0 ? a*=0
> ? b*=0 to? L*=100 ? a*=0 ? b*=0. I have placed 10 color sampler points to
> L*= 5, 15, 25, 35, 45, 55, 65, 75, 85 and 95, to keep track of their
> changes. I then converted this file into ?eciRGB v2? color space. The RGB
> values at these points came out to be R=G=B=13, 37, 64, 90, 114, 140, 165,
> 190, 216 and 242, respectively.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Starting with this neutral grey RGB gradient, I
> have done (relative colorimetric with black point compensation) conversions
> into FOGRA39 using ISO Coated v2 (ECI), into FOGRA51 using PSO Coated v3,
> into FOGRA47 using PSO Uncoated 12647 (ECI) and into FOGRA52 using PSO
> Uncoated v3. Below are the CMYK percentages for each of the 10 spots.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> FOGRA39 conversion:
>
> ??? >>>???? >???? >>>>> #01 / L*=05 a*=0 b*=0 / C=81 M=72 Y=65 K=85
>
> ??? >>>???? >???? >>>>> #02 / L*=15 a*=0 b*=0 / C=75 M=65 Y=61 K=73
>
> ??? >>>???? >???? >>>>> #03 / L*=25 a*=0 b*=0 / C=67 M=57 Y=55 K=58
>
> ??? >>>???? >???? >>>>> #04 / L*=35 a*=0 b*=0 / C=60 M=50 Y=49 K=44
>
> ??? >>>???? >???? >>>>> #05 / L*=45 a*=0 b*=0 / C=53 M=44 Y=43 K=33
>
> ??? >>>???? >???? >>>>> #06 / L*=55 a*=0 b*=0 / C=46 M=37 Y=36 K=22
>
> ??? >>>???? >???? >>>>> #07 / L*=65 a*=0 b*=0 / C=38 M=29 Y=30 K=13
>
> ??? >>>???? >???? >>>>> #08 / L*=75 a*=0 b*=0 / C=29 M=22 Y=23 K=06
>
> ??? >>>???? >???? >>>>> #09 / L*=85 a*=0 b*=0 / C=19 M=13 Y=13 K=02
>
> ??? >>>???? >???? >>>>> #10 / L*=95 a*=0 b*=0 / C=07 M=05 Y=05 K=00
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> FOGRA51 conversion:
>
> ??? >>>???? >???? >>>>> #01 / L*=05 a*=0 b*=0 / C=75 M=63 Y=50 K=89
>
> ??? >>>???? >???? >>>>> #02 / L*=15 a*=0 b*=0 / C=67 M=57 Y=47 K=77
>
> ??? >>>???? >???? >>>>> #03 / L*=25 a*=0 b*=0 / C=61 M=51 Y=44 K=62
>
> ??? >>>???? >???? >>>>> #04 / L*=35 a*=0 b*=0 / C=55 M=46 Y=40 K=48
>
> ??? >>>???? >???? >>>>> #05 / L*=45 a*=0 b*=0 / C=50 M=42 Y=37 K=35
>
> ??? >>>???? >???? >>>>> #06 / L*=55 a*=0 b*=0 / C=43 M=35 Y=32 K=22
>
> ??? >>>???? >???? >>>>> #07 / L*=65 a*=0 b*=0 / C=36 M=28 Y=26 K=12
>
> ??? >>>???? >???? >>>>> #08 / L*=75 a*=0 b*=0 / C=27 M=21 Y=20 K=05
>
> ??? >>>???? >???? >>>>> #09 / L*=85 a*=0 b*=0 / C=18 M=13 Y=13 K=01
>
> ??? >>>???? >???? >>>>> #10 / L*=95 a*=0 b*=0 / C=06 M=05 Y=04 K=00
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> As you can see, the same color is converted into a
> different C-M-Y balance as the L* value goes lower with the FOGRA51
> conversion. On the other hand, the C-M-Y balance is kept steady till the
> very dark shadows in FOGRA39. As the CMYK primaries are pretty much the
> same on both sides and the TVI curves, though different by about 1.7%, have
> the same C-M-Y balance, I cannot see any reason for the drop in Y as we go
> down the L* axis.
>
> ??? >>>???? > ????>>>>>
>
> ????>>>???? >???? >>>>> The situation is almost the same with FOGRA47 and
> FOGRA52.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> FOGRA47 conversion:
>
> ??? >>>???? >???? >>>>> #01 / L*=05 a*=0 b*=0 / C=81 M=62 Y=54 K=90
>
> ??? >>>???? >???? >>>>> #02 / L*=15 a*=0 b*=0 / C=75 M=59 Y=52 K=80
>
> ??? >>>???? >???? >>>>> #03 / L*=25 a*=0 b*=0 / C=65 M=53 Y=47 K=64
>
> ??? >>>???? >???? >>>>> #04 / L*=35 a*=0 b*=0 / C=58 M=48 Y=44 K=46
>
> ??? >>>???? >???? >>>>> #05 / L*=45 a*=0 b*=0 / C=49 M=40 Y=36 K=36
>
> ??? >>>? ???>???? >>>>> #06 / L*=55 a*=0 b*=0 / C=38 M=30 Y=28 K=27
>
> ??? >>>???? >???? >>>>> #07 / L*=65 a*=0 b*=0 / C=29 M=21 Y=20 K=20
>
> ??? >>>???? >???? >>>>> #08 / L*=75 a*=0 b*=0 / C=20 M=15 Y=14 K=14
>
> ??? >>>???? >???? >>>>> #09 / L*=85 a*=0 b*=0 / C=12 M=08 Y=08 K=08
>
> ??? >>>???? >???? >>>>> #10 / L*=95 a*=0 b*=0 / C=04 M=03 Y=03 K=02
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> FOGRA52 conversion:
>
> ??? >>>???? >???? >>>>> #01 / L*=05 a*=0 b*=0 / C=85 M=62 Y=42 K=88
>
> ??? >>>???? >???? >>>>> #02 / L*=15 a*=0 b*=0 / C=76 M=58 Y=43 K=78
>
> ??? >>>???? >???? >>>>> #03 / L*=25 a*=0 b*=0 / C=66 M=54 Y=39 K=61
>
> ??? >>>???? >???? >>>>> #04 / L*=35 a*=0 b*=0 / C=58 M=47 Y=36 K=43
>
> ??? >>>???? >???? >>>>> #05 / L*=45 a*=0 b*=0 / C=49 M=40 Y=33 K=28
>
> ??? >>>???? >???? >>>>> #06 / L*=55 a*=0 b*=0 / C=40 M=32 Y=28 K=16
>
> ??? >>>???? >???? >>>>> #07 / L*=65 a*=0 b*=0 / C=33 M=25 Y=22 K=08
>
> ??? >>>???? >???? >>>>> #08 / L*=75 a*=0 b*=0 / C=24 M=17 Y=16 K=03
>
> ??? >>>???? >???? >>>>> #09 / L*=85 a*=0 b*=0 / C=15 M=10 Y=10 K=01
>
> ??? >>>???? >???? >>>>> #10 / L*=95 a*=0 b*=0 / C=05 M=03 Y=03 K=00
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> To approach the situation from another angle, I
> have also converted the same neutral grey RGB file into GRACoL2006 and
> GRACoL 2013 to see have how they perform under the same conditions. Here
> are the results:
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> GRACoL2006_Coated1v2 conversion:
>
> ??? >>>???? >???? >>>>> #01 / L*=05 a*=0 b*=0 / C=83 M=75 Y=71 K=87
>
> ??? >>>???? >???? >>>>> #02 / L*=15 a*=0 b*=0 / C=80 M=73 Y=70 K=69
>
> ??? >>>???? >???? >>>>> #03 / L*=25 a*=0 b*=0 / C=73 M=65 Y=64 K=49
>
> ??? >>>???? >???? >>>>> #04 / L*=35 a*=0 b*=0 / C=64 M=55 Y=55 K=34
>
> ??? >>>???? >???? >>>>> #05 / L*=45 a*=0 b*=0 / C=56 M=47 Y=47 K=23
>
> ??? >>>???? >???? >>>>> #06 / L*=55 a*=0 b*=0 / C=49 M=40 Y=40 K=12
>
> ??? >>>???? >???? >>>>> #07 / L*=65 a*=0 b*=0 / C=41 M=32 Y=33 K=04
>
> ??? >>>???? >???? >>>>> #08 / L*=75 a*=0 b*=0 / C=31 M=24 Y=24 K=00
>
> ??? >>>???? >???? >>>>> #09 / L*=85 a*=0 b*=0 / C=19 M=13 Y=14 K=00
>
> ??? >>>???? >???? >>>>> #10 / L*=95 a*=0 b*=0 / C=06 M=04 Y=05 K=00
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> GRACoL20013_CRPC6 conversion:
>
> ??? >>>???? >???? >>>>> #01 / L*=05 a*=0 b*=0 / C=80 M=71 Y=62 K=90
>
> ??? >>>???? >???? >>>>> #02 / L*=15 a*=0 b*=0 / C=75 M=67 Y=62 K=75
>
> ??? >>>???? >???? >>>>> #03 / L*=25 a*=0 b*=0 / C=69 M=60 Y=57 K=55
>
> ??? >>>???? >???? >>>>> #04 / L*=35 a*=0 b*=0 / C=62 M=53 Y=51 K=38
>
> ??? >>>???? >???? >>>>> #05 / L*=45 a*=0 b*=0 / C=55 M=46 Y=44 K=25
>
> ??? >>>???? >???? >>>>> #06 / L*=55 a*=0 b*=0 / C=46 M=38 Y=37 K=16
>
> ??? >>>???? >???? >>>>> #07 / L*=65 a*=0 b*=0 / C=39 M=30 Y=29 K=07
>
> ??? >>>???? >???? >>>>> #08 / L*=75 a*=0 b*=0 / C=30 M=23 Y=22 K=02
>
> ??? >>>???? >???? >>>>> #09 / L*=85 a*=0 b*=0 / C=18 M=13 Y=13 K=00
>
> ??? >>>???? >???? >>>>> #10 / L*=95 a*=0 b*=0 / C=06 M=04 Y=04 K=00
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Although the paper white of GRACoL2013 is now in
> line with 12647-2:2013, it does separate RGB into a C-M-Y balance very
> similar to GRACoL2006.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Extreme loss of yellow ink in areas mid-tone and
> upwards has many negative side effects. Rich blacks are bluish/purplish and
> many clients do not like that. Yellow ink typically prints last for a good
> reason. It contains varnishes that give the image extra gloss and rub
> resistance. It is also the least tacky of the inks. Hence, by reducing its
> amount in the separation causes even less yellow ink being transferred to
> paper. Wet on wet printing sometimes requires more of the final ink to be
> properly transferred not less.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> To get round this problem I have tried
> recalculating the profiles to get some grey axis correction when converting
> with perceptual rendering intent. The old ProfileMaker v5, CoPrA v4 and
> Color Toolbox v18 (with incremental control) all have the tools to
> compensate for the color of paper. Interestingly this feature does help in
> the highlight to mid-tone range but not in the mid-tone to shadow range.
>
> ????>>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> On a recent occasion, I have also witnessed the
> fact that inkjet contract proofs are not good in simulating the inherent
> shift towards blue/purple in the shadows. What may appear as a neutral
> shadow on a certified proof is printed with a blue/purple cast, which may
> not be visually acceptable the client.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> This problem needs to be addressed. Doing a
> conversion in Photoshop using a relative colorimetric or a perceptual
> rendering intent is quite misleading without switching on the Proof Color
> View with paper white simulation. You can only see the overall loss of
> yellow when you activate soft proofing. Given that Photoshop still leaves
> much to be desired in terms of soft proofing, especially with uncoated
> papers, you can only use verified/certified inkjet proofs to see the actual
> result of your RGB to CMYK conversion.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> While FOGRA39 and FOGRA47 do share an imaginary
> paper white (95,0,2), being close to a*=0 + b*=0, the conversions made by
> both profiles maintain some kind of paper relative neutrality. Even if the
> paper white simulated absolute colorimetric proofs are not precisely
> matching any real print substrate, we had over the years developed
> chromatic adaptation skills that would bridge the gap. While the prepress
> process is rather smooth with FOGRA39, bridging the gap between the
> contract proof and the real substrate has always been the problematic side.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> But with FOGRA51 (and as a matter of fact, for the
> same reason, with FOGRA52) prepress and proofing needs heavy tweaking after
> RGB to CMYK conversion to introduce some of the lost yellow back to the
> scene. If not done properly, a proof to print match is tricky especially if
> you have heavy areas in the image. Hence, the process as a whole became
> problematic.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Dear colleagues, I invite you to shed some light
> on this in mystery.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Best regards,
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Refik Telhan, EE B.Sc.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Light and Color Management Consultancy
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Aydogdu Sokak 12A, Tarabya Mahallesi
>
> ??? >>>???? >???? >>>>> Sariyer, 34457, Istanbul, Turkey
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> Mobile: + (90) (532) 426 21 87
>
> ??? >>>???? >???? >>>>> e-Mail: rtelhan(a)ofset.com rtelhan(a)icloud.com
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> P.S. The following link will let you download a
> PDF that contains screen shots of the above conversions. There are also
> four screen shots from the interface of CoPra 5, showing that the problem
> is related with the measurement data sets and not with the profiles
> calculated by Color Toolbox.
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>>
> https://www.dropbox.com/s/vqdjezncf8l60cq/FOGRA_Conversions.pdf?dl=0
>
> ??? >>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>>
>
> ????>>>???? >???? >>>>> _______________________________________________
>
> ??? >>>???? >???? >>>>> ECI-EN mailing list
>
> ??? >>>???? >???? >>>>> ECI-EN(a)lists.callassoftware.com
>
> ??? >>>???? >???? >>>>>
> http://lists.callassoftware.com/mailman/listinfo/eci-en
>
> ??? >>>???? >???? >>>> _______________________________________________
> ECI-EN mailing list ECI-EN@lists.callassoftware.comhttp://
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>
> ??? >>>???? >???? >>>> _______________________________________________
>
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>
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>
> ??? >>>???? >???? >>>>
> http://lists.callassoftware.com/mailman/listinfo/eci-en
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>?? --
>
> ??? >>>???? >???? >>>?? Florian S??l
>
> ??? >>>???? >???? >>>?? Go?lerstra?e 29
>
> ??? >>>???? >???? >>>?? 12161 Berlin
>
> ??? >>>???? >???? >>>?? +49 172 3091154
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>>?? _______________________________________________
>
> ???>>>???? >???? >>>?? ECI-EN mailing list
>
> ??? >>>???? >???? >>>?? ECI-EN(a)lists.callassoftware.com
>
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> http://lists.callassoftware.com/mailman/listinfo/eci-en
>
> ??? >>>???? >???? >>>
>
> ????>>>???? >???? >>> _______________________________________________
>
> ??? >>>???? >???? >>> ECI-EN mailing list
>
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>
> ??? >>>???? >???? >>>
> http://lists.callassoftware.com/mailman/listinfo/eci-en
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >> --
>
> ??? >>>???? >???? >> Florian S??l
>
> ??? >>>???? >???? >> Go?lerstra?e 29
>
> ??? >>>???? >???? >> 12161 Berlin
>
> ??? >>>???? >???? >> +49 172 3091154
>
> ??? >>>???? >???? >>
>
> ????>>>???? >???? >
>
> ????>>>???? >???? > --
>
> ??? >>>???? > ????> Florian S??l
>
> ??? >>>???? >???? > Go?lerstra?e 29
>
> ??? >>>???? >???? > 12161 Berlin
>
> ??? >>>???? >???? > +49 172 3091154
>
> ??? >>>???? >???? >
>
> ????>>>???? >????
>
> ????>>>???? >???? --
>
> ??? >>>???? >???? Florian S??l
>
> ??? >>>???? >???? Go?lerstra?e 29
>
> ??? >>>???? >???? 12161 Berlin
>
> ??? >>>???? >???? +49 172 3091154
>
> ??? >>>???? >????
>
> ????>>>???? >???? _______________________________________________
>
> ??? >>>???? >???? ECI-EN mailing list
>
> ??? >>>???? >???? ECI-EN(a)lists.callassoftware.com
>
> ??? >>>???? >???? http://lists.callassoftware.com/mailman/listinfo/eci-en
>
> ??? >>>???? >????
>
> ????>>>???? > _______________________________________________
>
> ??? >>>???? > ECI-EN mailing list
>
> ??? >>>???? > ECI-EN(a)lists.callassoftware.com
>
> ??? >>>???? > http://lists.callassoftware.com/mailman/listinfo/eci-en
>
> ??? >>>????
>
> ????>>>???? --
>
> ??? >>>???? Florian S??l
>
> ??? >>>???? Go?lerstra?e 29
>
> ??? >>>???? 12161 Berlin
>
> ??? >>>???? +49 172 3091154
>
> ??? >>>????
>
> ????>>>???? _______________________________________________
>
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>
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> ??? >>>????
>
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>
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>
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> End of ECI-EN Digest, Vol 87, Issue 1
> *************************************
>
5 years, 1 month
- 3
- 2
Issues related with the switch from FOGRA39/47 to FOGRA51/52
by Refik Telhan
Dear Colleagues,
It all started with a question raised by Mr. Martin Orpen in his mail dated 22.08.2018 on the colorsync-users list. There was then almost a week long discussion with an open end.
>From that point on, I have made several conversions using FOGRA39, FOGRA47, FOGRA51 and FOGRA52 based profiles. At some point I have started generating profiles with the FOGRA51 and FOGRA52 datasets in multiple profiling software applications with different settings to have a better understanding on what is going on.
Mr. Orpen’s original complaint was the lack of yellow in skin tones with conversions made with PSO Coated v3. But when I started doing conversions using this profile, I have ended seeing that that deficiency ih yellow is widespread. Furthermore, what was true for FOGRA51 was also true for FOGRA52-based profiles.
To simplify the matter, I have created a Photoshop file in L*a*b* color mode that contained a linear gradient from L*=0 – a*=0 – b*=0 to L*=100 – a*=0 – b*=0. I have placed 10 color sampler points to L*= 5, 15, 25, 35, 45, 55, 65, 75, 85 and 95, to keep track of their changes. I then converted this file into “eciRGB v2” color space. The RGB values at these points came out to be R=G=B=13, 37, 64, 90, 114, 140, 165, 190, 216 and 242, respectively.
Starting with this neutral gray RGB gradient, I have done (relative colorimetric with black point compensation) conversions into FOGRA39 using ISO Coated v2 (ECI), into FOGRA51 using PSO Coated v3, into FOGRA47 using PSO Uncoated 12647 (ECI) and into FOGRA52 using PSO Uncoated v3. Below are the CMYK percentages for each of the 10 spots.
FOGRA39 conversion:
#01 / L*=05 a*=0 b*=0 / C=81 M=72 Y=65 K=85
#02 / L*=15 a*=0 b*=0 / C=75 M=65 Y=61 K=73
#03 / L*=25 a*=0 b*=0 / C=67 M=57 Y=55 K=58
#04 / L*=35 a*=0 b*=0 / C=60 M=50 Y=49 K=44
#05 / L*=45 a*=0 b*=0 / C=53 M=44 Y=43 K=33
#06 / L*=55 a*=0 b*=0 / C=46 M=37 Y=36 K=22
#07 / L*=65 a*=0 b*=0 / C=38 M=29 Y=30 K=13
#08 / L*=75 a*=0 b*=0 / C=29 M=22 Y=23 K=06
#09 / L*=85 a*=0 b*=0 / C=19 M=13 Y=13 K=02
#10 / L*=95 a*=0 b*=0 / C=07 M=05 Y=05 K=00
FOGRA51 conversion:
#01 / L*=05 a*=0 b*=0 / C=75 M=63 Y=50 K=89
#02 / L*=15 a*=0 b*=0 / C=67 M=57 Y=47 K=77
#03 / L*=25 a*=0 b*=0 / C=61 M=51 Y=44 K=62
#04 / L*=35 a*=0 b*=0 / C=55 M=46 Y=40 K=48
#05 / L*=45 a*=0 b*=0 / C=50 M=42 Y=37 K=35
#06 / L*=55 a*=0 b*=0 / C=43 M=35 Y=32 K=22
#07 / L*=65 a*=0 b*=0 / C=36 M=28 Y=26 K=12
#08 / L*=75 a*=0 b*=0 / C=27 M=21 Y=20 K=05
#09 / L*=85 a*=0 b*=0 / C=18 M=13 Y=13 K=01
#10 / L*=95 a*=0 b*=0 / C=06 M=05 Y=04 K=00
As you can see, the same color is converted into a different C-M-Y balance as the L* value goes lower with the FOGRA51 conversion. On the other hand, the C-M-Y balance is kept steady till the very dark shadows in FOGRA39. As the CMYK primaries are pretty much the same on both sides and the TVI curves, though different by about 1.7%, have the same C-M-Y balance, I cannot see any reason for the drop in Y as we go down the L* axis.
The situation is almost the same with FOGRA47 and FOGRA52.
FOGRA47 conversion:
#01 / L*=05 a*=0 b*=0 / C=81 M=62 Y=54 K=90
#02 / L*=15 a*=0 b*=0 / C=75 M=59 Y=52 K=80
#03 / L*=25 a*=0 b*=0 / C=65 M=53 Y=47 K=64
#04 / L*=35 a*=0 b*=0 / C=58 M=48 Y=44 K=46
#05 / L*=45 a*=0 b*=0 / C=49 M=40 Y=36 K=36
#06 / L*=55 a*=0 b*=0 / C=38 M=30 Y=28 K=27
#07 / L*=65 a*=0 b*=0 / C=29 M=21 Y=20 K=20
#08 / L*=75 a*=0 b*=0 / C=20 M=15 Y=14 K=14
#09 / L*=85 a*=0 b*=0 / C=12 M=08 Y=08 K=08
#10 / L*=95 a*=0 b*=0 / C=04 M=03 Y=03 K=02
FOGRA52 conversion:
#01 / L*=05 a*=0 b*=0 / C=85 M=62 Y=42 K=88
#02 / L*=15 a*=0 b*=0 / C=76 M=58 Y=43 K=78
#03 / L*=25 a*=0 b*=0 / C=66 M=54 Y=39 K=61
#04 / L*=35 a*=0 b*=0 / C=58 M=47 Y=36 K=43
#05 / L*=45 a*=0 b*=0 / C=49 M=40 Y=33 K=28
#06 / L*=55 a*=0 b*=0 / C=40 M=32 Y=28 K=16
#07 / L*=65 a*=0 b*=0 / C=33 M=25 Y=22 K=08
#08 / L*=75 a*=0 b*=0 / C=24 M=17 Y=16 K=03
#09 / L*=85 a*=0 b*=0 / C=15 M=10 Y=10 K=01
#10 / L*=95 a*=0 b*=0 / C=05 M=03 Y=03 K=00
To approach the situation from another angle, I have also converted the same neutral gray RGB file into GRACoL2006 and GRACoL 2013 to see have how they perform under the same conditions. Here are the results:
GRACoL2006_Coated1v2 conversion:
#01 / L*=05 a*=0 b*=0 / C=83 M=75 Y=71 K=87
#02 / L*=15 a*=0 b*=0 / C=80 M=73 Y=70 K=69
#03 / L*=25 a*=0 b*=0 / C=73 M=65 Y=64 K=49
#04 / L*=35 a*=0 b*=0 / C=64 M=55 Y=55 K=34
#05 / L*=45 a*=0 b*=0 / C=56 M=47 Y=47 K=23
#06 / L*=55 a*=0 b*=0 / C=49 M=40 Y=40 K=12
#07 / L*=65 a*=0 b*=0 / C=41 M=32 Y=33 K=04
#08 / L*=75 a*=0 b*=0 / C=31 M=24 Y=24 K=00
#09 / L*=85 a*=0 b*=0 / C=19 M=13 Y=14 K=00
#10 / L*=95 a*=0 b*=0 / C=06 M=04 Y=05 K=00
GRACoL20013_CRPC6 conversion:
#01 / L*=05 a*=0 b*=0 / C=80 M=71 Y=62 K=90
#02 / L*=15 a*=0 b*=0 / C=75 M=67 Y=62 K=75
#03 / L*=25 a*=0 b*=0 / C=69 M=60 Y=57 K=55
#04 / L*=35 a*=0 b*=0 / C=62 M=53 Y=51 K=38
#05 / L*=45 a*=0 b*=0 / C=55 M=46 Y=44 K=25
#06 / L*=55 a*=0 b*=0 / C=46 M=38 Y=37 K=16
#07 / L*=65 a*=0 b*=0 / C=39 M=30 Y=29 K=07
#08 / L*=75 a*=0 b*=0 / C=30 M=23 Y=22 K=02
#09 / L*=85 a*=0 b*=0 / C=18 M=13 Y=13 K=00
#10 / L*=95 a*=0 b*=0 / C=06 M=04 Y=04 K=00
Although the paper white of GRACoL2013 is now in line with 12647-2:2013, it does separate RGB into a C-M-Y balance very similar to GRACoL2006.
Extreme loss of yellow ink in areas mid-tone and upwards has many negative side effects. Rich blacks are bluish/purplish and many clients do not like that. Yellow ink typically prints last for a good reason. It contains varnishes that give the image extra gloss and rub resistance. It is also the least tacky of the inks. Hence, by reducing its amount in the separation causes even less yellow ink being transferred to paper. Wet on wet printing sometimes requires more of the final ink to be properly transferred not less.
To get round this problem I have tried recalculating the profiles to get some gray axis correction when converting with perceptual rendering intent. The old ProfileMaker v5, CoPrA v4 and Color Toolbox v18 (with incremental control) all have the tools to compensate for the color of paper. Interestingly this feature does help in the highlight to mid-tone range but not in the mid-tone to shadow range.
On a recent occasion, I have also witnessed the fact that inkjet contract proofs are not good in simulating the inherent shift towards blue/purple in the shadows. What may appear as a neutral shadow on a certified proof is printed with a blue/purple cast, which may not be visually acceptable the client.
This problem needs to be addressed. Doing a conversion in Photoshop using a relative colorimetric or a perceptual rendering intent is quite misleading without switching on the Proof Color View with paper white simulation. You can only see the overall loss of yellow when you activate soft proofing. Given that Photoshop still leaves much to be desired in terms of soft proofing, especially with uncoated papers, you can only use verified/certified inkjet proofs to see the actual result of your RGB to CMYK conversion.
While FOGRA39 and FOGRA47 do share an imaginary paper white (95,0,2), being close to a*=0 + b*=0, the conversions made by both profiles maintain some kind of paper relative neutrality. Even if the paper white simulated absolute colorimetric proofs are not precisely matching any real print substrate, we had over the years developed chromatic adaptation skills that would bridge the gap. While the prepress process is rather smooth with FOGRA39, bridging the gap between the contract proof and the real substrate has always been the problematic side.
But with FOGRA51 (and as a matter of fact, for the same reason, with FOGRA52) prepress and proofing needs heavy tweaking after RGB to CMYK conversion to introduce some of the lost yellow back to the scene. If not done properly, a proof to print match is tricky especially if you have heavy areas in the image. Hence, the process as a whole became problematic.
Dear colleagues, I invite you to shed some light on this in mystery.
Best regards,
Refik Telhan, EE B.Sc.
Light and Color Management Consultancy
Aydogdu Sokak 12A, Tarabya Mahallesi
Sariyer, 34457, Istanbul, Turkey
Mobile: + (90) (532) 426 21 87
e-Mail: rtelhan(a)ofset.com rtelhan(a)icloud.com
P.S. The following link will let you download a PDF that contains screen shots of the above conversions. There are also four screen shots from the interface of CoPra 5, showing that the problem is related with the measurement data sets and not with the profiles calculated by Color Toolbox.
https://www.dropbox.com/s/vqdjezncf8l60cq/FOGRA_Conversions.pdf?dl=0
5 years, 1 month
- 10
- 62
Question about GWG2.0 Spot to CMYK Overprint (also FOGRA and PDF/X-Ready certification)
by Jan-Peter Homann
Hello to the PDF specialists,
I have a customer, who wants to be ISO 12647-8 certified by FOGRA with a
high end CMYK Inkjet solution.
The certification includes the PDF/X-Ready output suite 3.02 which
contains the patch GWG2.0 Spot to CMYK overprint.
With the current RIP version this patch shows crosses in a different
green, than the rectangles.
/The GWG readme for this patch states://
//A faint ‘X’ in slightly darker green may show in all of the tests;
this is acceptable behavior in this patch. Only a clearly visible X
indicates an incorrectly rendered patch. Please see example on the first
page of this README file.//
//This patch appears to be a simple patch, and should be rendered
without fail on its own. It is, however, possible that the amalgamation
of this patch with other patches may very well lead to problems. There
are several cases in which objects set to overprint using Spot colors
can prove to create some advanced problems. For example, If you simulate
Spot colors for proofing or commonly convert Spot colors to CMYK this
patch can be used to highlight potential errors in your working
practices. Use this patch along with patch 10 —Spot to CMYK conversions
for testing Spot color simulation./
If I open the patch in Acrobat Professional and activate overprint
simulation I don´t see any crosses (expected behavior). In output
preview (german Ausgabevorschau) I measure, that the overprinting
objects have only a tone value of 1% (in the top row CMYK overprints
spot, in the bottom row spot overprints CMYK). The object inspector does
not show an alternate colorspace for the spot color objects in GWG green.
The standard output intent for the patch is ISOcoatedv3_300_eci.icc If I
change the simulation profile in Acrobat Pro to quite different printing
conditions like e.g. newspaper or Epson inkjet profiles, all patches
stay perfect green - no crosses.
I talked with the RIP vendor for the solution and also they are
surprised. In 2016 internal test showed perfect patches with no visible
crosses. Now we see two different greens. Concerning the GWG readme,
this is an acceptable behavior.
Both the customer, the RIP vendor and I want to understand, what is
happening here. Between 2016 and today, the RIP solution got an update
of the Adobe PDF Print Engine (APPE). As the printer uses only CMYK for
printing, the RIP must convert overprints between spot and CMYK to CMYK
only.
I have following questions to the PDF-specialists in this list:
1) Is it possible, that an APPE update changes the behaviour how
overprints between spot and CMYK are rendered to CMYK only ?
2) Why i don´t see an alternate colorspace for GWG green in the object
inspector of Acrobat Pro ?
3) Why I don´t see slight crosses in Acrobat Pro, when I change the
simulated print condition ?
4) Does GWG has an mailinglist to aks such questions ? (I didn´t found
it on the GWG website...)
Thank you for any hints
Jan-Peter
--
Homann colormanagement tel: +49 30 611 075 18
Jan-Peter Homann mob: +49 171 54 70 358
Herzbergstr. 55 www.colormanagement.de
10365 Berlin mailto:homann@colormanagement.de
5 years, 1 month
- 2
- 1