Re: Fogra 51 and 52
Re: Fogra 51 and 52
- Subject: Re: Fogra 51 and 52
- From: Graeme Gill via colorsync-users <email@hidden>
- Date: Fri, 14 Jun 2019 09:17:25 +1000
Refik Telhan wrote:
Hi,
> The "coldness" I am referring to is the coldness of the FOGRA51/52
> separations in
> comparison to ones made by FOGRA39/47. When we do the color conversion to
> both
> colorspaces in Photoshop in RelCol+BPC mode, we end up with two distinct CMYK
> structures. Both are paper relative. What we are seeing in Photoshop (with
> Proof View
> OFF) is the color of the ink-film made by the CMYK layers.
right, but the CMYK "structure" is irrelevant - it's the color that counts.
> We are assuming that both printers are able to hit the targets of their
> respective
> printing conditions. In the end, you will see that the prints made by Printer
> A are
> "visually" more neutral then what Printer B did.
Evaluating it in what conditions ?
> This is the problem plaguing the
> industry since the very first day FOGRA51/52-based profiles have been
> released. And
> this is why these profiles have faced lukewarm acceptance.
Sounds like they are being misused.
> While the proof-to-print match has immensely improved with the switch to M1
> measurement
> mode in FOGRA51, the neutrality of the ink-film is broken. Using the same
> inks and the
> same papers that we have been using for the last 10-12 years, we are now
> having colder
> (yellow-deficient) separation/prints.
As it should be from the measured color. If that doesn't look right at
the end of the day, then the measurement conditions aren't a match
for the viewing conditions. So change one to match the other.
> The situation is catastrophic along the FOGRA47-FOGRA52 line. I typically
> generate
> higher GCR versions of datasets to use in situations where gray balance is
> critical.
Right. And as you raise black you will loose yellow, because the K only
black is warm when measured on the FOGRA51/2 paper under M1.
> The loss of yellow is also evident in the FOGRA51-based
> "PSOuncoated_v3_FOGRA52.icc".
> Just view the neutral rendering curves of "PSOuncoated_v3_FOGRA52.icc" and
> the FOGRA-47
> based"PSO_Uncoated_ISO12647_eci.icc" profiles next to each other.
The amount of yellow is irrelevant - it's the measurement and appearance
that counts. CMYK is just a way of getting to a result.
> i1Profiler 'freely' replaces yellow with black (in the dark end of the tonal
> range) and
> represents the worst case. Other profiling packages are more "merciful"
> against yellow,
> but they all reduce it is to some extent when they are using the FOGRA52
> dataset.
It's not the software that's doing this, it's the data. The measurements say
that the CMY black is in line with the paper white point, while the K only
black is warm. So as you increase the K, yellow has to be dropped.
i.e. it's all working as intended.
(Although dealing with a CMYK device that has different CMY and K blacks
can make it difficult to get smooth transitions in the shadow regions.)
> While the yellow ink is not to most significant ink in terms of building the
> L* value
> of the rich black, it is very important in creating other physical properties
> of the
> printed image. It carries the waxes that provide rub-resistance and the
> varnishes that
> provide gloss. And this gloss adds to the visual depth of the rich black.
> Yellow ink
> also "masks" the pinkish reflection made by the solid magenta ink.
Right. So if you need more yellow for reasons other than the color, then
you need to reduce K in your separation, or switch to M0 or M2
conditions, or use a paper with less FWA/OBE, or use a black ink
that is cooler and/or blocks less UV.
> But FOGRA51/52-based profiles are not producing
> neutral ink-films.
But they are producing neutral ink films as confirmed by the measurement/profile
data. It's just not the sort of separation you are used to.
Dealing with FWA/OBE is hard and can never be perfect, because of
uncontrolled levels of UV in real viewing environments.
That's the trade-off for switching to cheap paper. If you
(really meaning your customer or customers customer)
don't want these problems, don't use FWA/OBE laden paper.
[ Sorry - I know a lot of the pain here is that an industry/structural
problem has been created. FOGRA51/52 has been thrown in as if it
was an "upgrade" from what has come before, whereas it is really
a completely new paradigm. So there is dislocation. ]
Cheers,
Graeme Gill.
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