Re: Images for print
Re: Images for print
- Subject: Re: Images for print
- From: Marco Ugolini <email@hidden>
- Date: Sat, 11 Oct 2008 00:40:47 -0700
- Thread-topic: Images for print
In a message dated 10/10/08 4:37 PM, Roger Breton wrote:
> Supposedly, the increased densities made possible a much wider printable
> gamut. But, don't we all know that densities are, to some extent, meaningless
> without colorimetric information?
Hi Roger.
I don't claim to have the level of understanding that Bill has of all the
aspects of what he achieved with his book, but it seems logical that in
order to increase printed gamut one has to increase both ink densities and
purity/concentration. VANFU provided inks that were both reformulated and
used at higher densities. (The densities obviously have an upper limit, and
can only be as high as the substrate will allow. So, the paper is the third
factor in the equation, along with reformulation and densities.)
The results in Bill's book are undeniably more brilliant and saturated than
the best standard sheetfed output. His was a groundbreaking achievement. I
have little doubt that the colorimetric information would confirm that.
> For example, the IDEAlliance 2007 Guidelines clearly states that Lab values
> take precedence over densities. In my view, a better account of the alleged
> extended gamut afforded by the Vanfu inks would have been better conveyed
> through CIELab values instead of densities.
I agree that I too would have liked to see the colorimetric data relative to
the primaries, secondaries, etc., as well as examine a copy of the spectral
measurements or the ICC profile of VANFU's press output. That would provide
a picture of the achievement that speaks more directly to me than the
density values (as impressive as those are in their own right).
I have not yet been able to see that kind of information anywhere regarding
Bill's book.
> Don't you think? An even better account would have been to post the
> measurements of the Spectroscan, somewhere for people to download and
> look for themselves, no?
That would be very interesting, yes.
> Second, if you look closely at page 219, you'll see a GretagMacbeth D19C
> look-alike densitometer on the table. Let me speculate that the "high" density
> figures reported by the author are actually StatusG densities, with polarizer,
> the kind widely practiced in Europe and Asia. To give you an idea, a solid
> yellow density of 1.00 in North America's StatusT is reported as 1.30 in
> Europe's StatusG with polarizer. Not a small difference.
On page 113 of the PDF, Bill compares the VANFU densities to the standard
SWOP densities. It would not make sense to compare the two sets if they
weren't both expressed in the same scale (I assume Status T).
> While it's entirely possible that Vanfu inks live up to the claimed higher
> pigmentation levels, allow me some degree of skepticism.
Skepticism that they were not highly concentrated? Or that the densities
were not as high as claimed? Or both?
> Third, I suspect a lot of the stone colors themselves aren't all that
> saturated to begin with. You tell me where are the highly saturated colors on
> page 12, 16, 17, 18, 19, 25 and 26, to name only these few.
Yes, but then there are pages 21, 28, 31, 34, 38, 47, etc.
> Granted the RGBs in the PDF may not do justice to the chroma of certain
> details,
That is a possibility.
> but one could very well argue "why bother with high pigmented inks
> in the first place" for those images?
Well, the whole book had to be printed with one set of inks, right? It would
not be practical to use different inks and densities for different portions
of the book.
It's a matter of finding the combination of screening/inks/densities/paper
that gives the best results with the most difficult images, and then print
the whole book that way.
> And, yes, (I can't resist saying this) for those very images, sRGB would have
> more than adequately capture their exact colorimetry without clipping. No
> offense to the author.
I don't recall reading information anywhere on which RGB working space was
used for the master files, but it would make sense if it was ProPhoto RGB.
> Fourth, nowhere in the PDF is there mention of how close was the match between
> the proofs and the printed output from the press? If we buy the argument that
> the inks lent such a high gamut to begin with, it's not far fetch to think
> that the proof was unable to enclose that extended press gamut accurately or
> completely. Page 98 shows an Epson 9600. Who knows what proofing paper was
> thrown on there? What was the RIP front-end? The Ultrachome inks in the 9600
> are not known to have all that great of gamut, you know.
Good question. I don't know how the proofing was done. Perhaps the inkjet
proofs were seen as just an approximation, with the knowledge that the final
outcome would be brighter still.
Also, the subject matter is abstract enough that there are no "memory
colors" involved (skin tones, skies, grass, etc.). So there is really no way
to be "wrong" in the results, and one can let the chips fall where they may.
> Perhaps the author could post the measurements somewhere for people to
> examine?
That would be a treat.
Marco Ugolini
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