Re: Creating ICCs with pigmented inks
Re: Creating ICCs with pigmented inks
- Subject: Re: Creating ICCs with pigmented inks
- From: Chris Murphy <email@hidden>
- Date: Tue, 2 Jul 2002 23:57:39 -0600
Graeme Gill <email@hidden> writes:
>
We're not talking the same language. There is no such thing as
>
an ink which is "illumination dependent", unless it is photosensitive.
I meant to write illuminant dependent - as in the color you get depends
on the spectral reflectance of the inks. And some inks are a whole lot
more dependent on the illuminant than others. And by illuminant I mean
spectral power distribution. Everything has some level of illuminant
dependence. I think the term used when comparing the shifting of a color
sample under various light sources is color constancy.
>
If
>
the shape is similar enough to the target ink, then they will match
>
under a wide range of illuminants (they are a good spectral match),
>
and if they are rather different (extreme, think CRT spectra vs. print),
>
then they will be a good match under a more restricted range
>
of illuminants.
The original Epson pigment inks don't match up well spectrally to press
inks at all.
>
Unless you are very lucky, or choose your
>
inks to match just one target, 4 inks is not enough to create a general
>
purpose spectral matching based color reproduction system.
While it might be nice to have such a thing, that's usually not the goal.
The goal is to get a colorimetric match, which is by definition is
illuminant dependent.
>
Maybe on some profiling systems, but the better ones let
>
you choose the illuminant you will actually be using :-)
Yeah but there is only what - one of these apps available? Profile City's
app is the only one I can think of that will compute something other than
D50 LAB from spectral measurements.
>
Again, it depends on the color setup and the RIP.
I totally disagree. It has a WHOLE lot more to do with image content. The
more neutral the image, the more these printers fail to produce neutrals
that are consistent in various lighting conditions. You can't print a
shade of biege with only black ink. There has to be some yellow in there,
and yellow is the biggest problem with the ink set. Bieges are a
nightmare to reproduce on these printers and have it come out exactly the
way you want unless you're going to include a portable viewing box with
up to date bulbs with every proof you sell, and permanently attach the
proof and the box together.
I've yet to see any pigment based prints containing anything other than
saturated colors have good color constancy (in various lighting
conditions). Now if you want to prove me wrong, send me an email and I'll
give you my mailing address. I'd like to see some proofs illustrating it.
>
Obviously
>
there are some who have done it badly. Pity the ink has been
>
blamed for it.
Graeme, if it weren't the ink, why did Epson totally redesign it? Why
does it perform SOOO MUCH more like the dye based inks? I don't see a
paper change occuring to solve the problem. And I don't see a retroactive
driver update from Epson to fix the problem with the previous pigment
inkset based printers to try to solve the problem merely with black
generation. If I recall correctly they DID do this with the 5500, which
did very noticably improve the situation but did not solve the problem
and added noticable black dots in highlights and 1/4 tones (and hence
skin tones).
>
The one
>
think I don't like so much about it is the amount of
>
bronzing it has. The Ultrachrome is even worse in this
>
regard.
Not sure what you mean by bronzing.
>
But blanket statements are being made canning pigment,
>
when I have the evidence in front of me that it is probably
>
the best overall choice.
I haven't heard anyone canning pigment based inks. I've heard people for
months and months complaining about a particular pigment based inkset
which happens to be used in Epson 2000P, 7500, 9500 and the 10000 (with
archival ink option).
>
The fact that some people don't seem to
>
have the tools or knowledge to make profiles for it, isn't
>
a reason to claim that it's inherently no good.
You send me some proofs, I'd like to see for myself.
>
So its pot luck as to whether it is stable or not ?
No, as I said from the outset, the stability of the ink is extremely
dependent on the paper being used. Dye based ink stability is just very
dependent on having the right chemistry in the receiving paper (in the
form of coatings).
Chris Murphy
Color Remedies (tm)
Boulder, CO
303-415-9932
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