Digital BW, The Print

Alan wrote:

>Regarding metamerism,   virtually all colorants -
>paints, inks, dies - look different under different light. ...

Without attempting to get into the physics of metamerism, ... I agree.

I always try to be careful to qualify my statements about "metamerism" with
some word like "significant" or "problematic."  I simply take the prints and
samples of ink I'm looking at under different light sources and see if I
like the way they look.  Do they look appropriate given the light source?
If there is an obvious and objectionable green in daylight and magenta in
other light, then the metamerism is a problem for me.

I was hoping that the X-Rite spectrophotometer would be able to measure the
effect (as the company representative claimed), but it doesn't (or I don't
know how to operate the instrument).  The "light source" settings one can
make in the software show no difference in readings even with the worst
Epson Archival "B&W" prints.

The VM-S inkset, which has the most obvious metamerism of the quad inksets I
work with, also doesn't have what I'd call "objectionable" metamerism.  With
the sepia or light sepia curve there is a lot of yellow pigment in the
print, and this is usually said to be the source of most of the problematic
metamerism.  However, there is also a lot of magenta in the toner.  When I
view one of the sepia prints with tungsten light, it is very warm.  When I
turn the print toward daylight, it shifts significantly, but it appears to
simply get more neutral.  I suspect there is so much magenta in the mix that
what would have been seen as a green shift if the print were neutral, is
simply hidden by all the magenta.

Paul
http://www.PaulRoark.com
_____________________________________

-----Original Message-----
From: Alan Zinn [mailto:AZinn@...]
Sent: Thursday, April 10, 2003 9:15 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: RE: [Digital BW] Metamerism and MIS VM Inks


At 08:58 AM 4/9/03 -0700, you wrote:
>Stan,
>
>You wrote:
>
> >David Brooks at Shutterbug Magazine has suggested to me that
> >perhaps the reason I don't see metamerism in my 1270 prints
> >with MIS VM inks is that the inks are not 100% pigment. ...
>
>Not all pigments are significantly affected by metamerism.  Also, dyes are
>not free from it.  The Lyson quads, for example, are, I believe, afflicted
>with the problem even though they are dye based.
>
>As it turns out, the MIS VM inks appear not to be pure pigment.  The black
>used to make the grays (the old MIS Archival black) probably does have some
>dye in it.  However, that has nothing to do with the lack of metamerism.
>The new MIS Ultra Tone B&W inkset is pure pigment and does not have any
>significant metamerism problem.
>
>I suspect the reason many associate metamerism with pigments could be that
>the Epson pigments are badly affected by it, perhaps due to the resin
>coating on the particles.  It may also be the case that the color third
>party pigments have some metamerism.  However, I don't think I've ever seen
>a significant problem with carbon black pigments, which is mostly what the
>MIS pigment-base quads are.
>
>In fact, the yellow pigment is the one ink that is usually blamed for most
>of the metamerism problem with color pigments.  With the MIS VM and Ultra
>Tone inksets, carbon is the base pigment, and the toners are composed of
>cyan and magenta -- there is no yellow pigment in them.  (The VM-S does
have
>yellow in the toner.)
>
>I hope this helps.  (And I wish magazine writers would spend more time
>learning what the quad inks are all about.  It's still the only way to get
>top notch digital B&W output at a reasonable price.)
>
>Paul
>http://www.PaulRoark.com
Paul,

Regarding metamerism,   virtually all colorants - paints, inks, dies - look
different under different light.   A water color painting (which contains
both pigment and dye) or litho print won't look exactly the same under
every light source.   It would seem that full color ink jet images would be
no different than with other media. It is only with attempts to create
monochrome from CMYK inks that it becomes a problem. Or is it a
problem?  Do we see ANY picture outside a gallery in it's ideal light? I
don't see how  that ever can be corrected given all the paper, ink, dye
variables. It seems to me that a more workable solution, with regard to
gallery display at least, would be to correct for two types of light
sources like film.  There could be a warm light or cool light set of inks
or adjustments.

AZ




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