Re: Creating ICCs with pigmented inks
Re: Creating ICCs with pigmented inks
- Subject: Re: Creating ICCs with pigmented inks
- From: Graeme Gill <email@hidden>
- Date: Tue, 02 Jul 2002 16:19:37 +1000
Chris Murphy wrote:
>
I haven't seen any data indicating the dye inks are unstable, let alone
>
seriously unstable, in the Epson 10000.
Our test runs on the Epson Glossy film with the Dye ink
gave the following results:
Time Avg DE Worst DE
1 day 1.5 6
6 days 2 7.5
18 days 3 9
5 weeks 4.5 15.5
7 weeks 5 17
11 weeks 5.5 21
12 weeks 6 22
16 weeks 6.5 23
ie. appallingly bad for proofing purposes.
>
Like any dye based ink from an
>
inkjet printer, they are susceptible to dry back, fading, and hue shifts
>
if they aren't used with a paper with a compatible chemistry. Even the
>
very early Epson die inks, which were notoriously unstable over a 12 hour
>
period exhibiting gray balance shifts in excess of 18 delta E's could be
>
stablized to within 15 minutes of drying by using suitable papers (which
>
at the time were not available through Epson).
To be fair, I guess results might be different using one of
the other media, but it doesn't seem to be very sensible to
use ink that is capable of such a poor performance in this
regard. Our results with the Pigment were an order
of magnitude better than those above.
>
The problem with the pigment based inks used in the Epson 2000, 7500,
>
9500 and 10000 w/ pigment ink option, is that they are extremely
>
susceptible to metamerism.
What makes you say that ? The spectral characteristics of the pigment
inks is not that dissimilar to other media, and in any case, none of
these 3 or 4 color systems are capable of anything other than
a metameric match. The implication of course is that you will
only get a perfect match under the lighting conditions (and with
the observer) it has been set up for. The research I've read on spectral
matching indicates that you need something like 6-8 carefully selected
inks to hope to do well at this, and as far as I'm aware, there
are no commercial proofing systems that claim spectral matching.
>
I have yet to see a print from any of these
>
printers that would not under drastic shifts in neutrals (saturated
>
colors are not as affected) when moving between different light sources.
>
Even 5000K fluorescent would cause this to occur.
It is easy to get very stable neutrals using pigment ink simply
by maximizing the black usage. We certainly haven't seen any worse
behaviour in this regard on the 10000 pigment than any other
inkjet device. Stable neutrals doesn't mean that it matches
the target media though, since the target media is also
subject to metamerism, and its neutrals may change under
the different lighting. Something closer to a spectral
match is probably a proof that has a similar CMYK composition
to the target (which is what we have done).
>
Uhh, because for proofing, it works, that's why. If you want a long
>
lasting print, go pigment.
Most of our customers are looking for a proof that will be useful
for at least a couple of weeks, if not as long as a year. Pigment
works for proofing, whereas our experience with dye indicates that
it isn't stable for even a week.
>
If you want a reliable short term proof under
>
5000K fluorescent then go dye.
and pigment will work just as well under 5000K fluorescent or whatever,
if you've profiled it properly, and if the RIP does the right thing.
>
The various press proofing related forums
>
have been ripe for some time regarding these problems with Epson pigment
>
inks (the ones in the printers listed). It's a widespread and known
>
problem.
Problems with how they've been profiled, and the RIP I'd think.
>
>Good luck getting a print to stay the same color with the
>
>Dye ink.
>
>
For how long? Within 15 minutes of drying, compared to 12 hours later I
>
measured a negliglbe delta E with an Epson 10000 dye printing on Photo
>
Luster paper.
See above.
>
Needing them to last 70 years isn't one of
>
those needs.
But having them be stable for a couple of weeks is.
Graeme Gill.
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