Metamerism when printing over the network

  • Thread starter Thread starter Guillaume Dargaud
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Guillaume Dargaud

Today I noticed the weirdest problem.
I'm trying to print some pictures on an Epson R1800 as a networked printer.
If I print directly from the computer via USB, I get a fine print.
If I print the same image over the network, with all the exact same driver
options, I get huge metamerism defects on the print.
I've checked and rechecked the driver options and am at a loss.
Anybody can offer a clue ?

Is it possible that some information, like the gloss optimizer, gets
discarded when doing a network print ?
 
Let's first define terms to make sure we are speaking about the same things.

Metamerism is the quality of a inkset to make prints which have
different color values relative to one another when viewed under
different lighting conditions or different color temperatures. Now, of
course, all colors change hue when viewed in different light sources,
but this is when the colors do not respond in a similar manner to the
lighting. So, for instance an image seen under low color temperature
incandescent would be expected to have all the colors appear warmer and
more toward the yellow orange spectrum, however with metamerism,
instead, one color, let's say red, instead shifts toward the blue
instead of the yellow orange side.

Another phenomenon is bronzing, which is different. This is when a
usually darker color ink under higher coverage and density will tend to
have a metallic (often yellowy metallic reflection when viewed under
certain lighting and angle). often making the image look like a negative
reversal (darkest areas appear brightest).

Lastly, there is gloss differential. This is when the inks are quite
glossy or matte, and the paper is toward the opposite reflective
quality. As a result, areas which have high density/coverage tend to
exhibit either the glossy or matte nature of the ink moreso, and again
with certain angles and lighting this differential between the raw paper
and the inks with heavily coverage shows this up clearly.

Metamerism is caused by the nature of how the ink sits on the page and
the dyes/pigment used and how the dithering patterns interact with
light. Pigment inks tend to have more metamerism than dye inks, and the
R1800 does use pigment inks. Unless the network is somehow altering the
dithering patterns of the driver (or using a different driver
completely) I do not see how this is happening.

Both Bronzing and gloss differential can be effected by GLOP (The gloss
optimizer) Less GLOP the more bronzing or gloss differential will be
visible.

Art
 
Arthur has explained the similarities between Metamerism and Bronzing very
well but for you to suggest that the problem could be down to a network is
pushing that suggestion a little to far, most printers accept what the
computer is sending and only then translates on how it is to print that
instruction, most Epson printers using pigment ink suffer Bronzing although
reduced somewhat by the addition of the optimiser which is Epsons rather
poor effort of trying to control Brozing, I would say the problem is firmly
laid at the setting used and not the network. I see again you make no
mention of which paper or ink used, or is it a picture or a photo, I have
heard both called the same, I would ask for example, do you get the same
result with Epson glossey paper.
 
Thanks for the details on metamerism vs bronzing vs gloss differential. In
this case I believe it's simply a lack of gloss finish leading to a strong
bronzing of the image.
What is weird is that I use the same printer with the same paper (Epson
glossy) and apparently the same driver option. The only difference is that
in one case the printing is done over the network. I'm used to troubleshoot
computer issues, but this one has really stumped me.
Yes, I've triple checked the driver settings. Using WinXP.
 
I am not versed on networks, so this may be just ignorance, (yeah, I'm
just waiting for someone to tell me what a fool I am, etc, so go right
ahead, I can take it) but I wonder if there is something in the
R800/R1800 driver that is being filtered out by the network. Could it
be the driver uses an extra bit to trigger the GLOP that the network
isn't "wide" enough to transfer?

GLOP isn't part of the CMYK data, per se and is not directly related to
color output, but instead low overall ink coverage triggers the GLOP.
Each ink has "GLOP" in it, but if the area is only lightly covered with
ink, (or none at all as with white) the printer adds extra GLOP to bring
the gloss level up.

Art
 
I love the polite way you explain what the extra Glop tries to achieve. My
blunt opinion is that it tries to hide the problem of Bronzing which I first
noticed with the 2100. I feel that Epsons R & D department have still not
got to grips with the problem and comming up with an ink other than
Pigmented or a paper that will do the job without Bronzing. In the days of
the 2100 Epson could not even recommend a glosey paper for that machine,
semi was their best suggesion, no matter what people say there is still
Bronzing although reduced with the R1800 and R2400. The introduction of
GLOP is a cheapie fix which costs the user every time they replace it, some
solution for major player in the printer market.
 
Are you sharing this printer from your PC or are you using a print
server, or does the printer have an internal nic? I know some printer
manufacturers are quite specific about which print servers to use with
their printers.
 
I wasn't attempting to be "polite" really.

The problem is that pigment inks use colorants which have a undissolved
physical granular product. Those grains tend to be matte and cannot
enter the paper surface as dye colorants can. Dye colorants actually
migrate below the paper surface, so the paper surface determines the
reflective properties of the print (glossy, satin, semi-gloss, matte,
etc). With pigment inks, while they do fine on most matte surfaces,
both because they are able to integrate with the matte surface since
matte surfaces tend to have enough "terrain" for them to fit into, the
pigment colorant requires an adhesive on semi-gloss or gloss surfaces or
it tends to rub off when dry. This is what "resin encapsulation" is all
about. Since the pigment particles sit on the top surface of the paper,
they alter the reflective qualities of the surface wherever they sit.
Epson, with the R800 and R1800 series decided to try to resolve this by
adding a glossy media to the ink to try to maintain the gloss on a gloss
paper, but the problem was places that the ink was sparsely placed,
making a matrix of the ink and paper, in those cases the printer added
extra glossy media to try to even out teh gloss levels. The white,
having no ink, also beenfits frotheaving teh gloss media coating it.

This isn't really about bronzing, as much as gloss differential. I
understand the new K3 ink set (in the 2400, for instance) has resolved
most of the gloss differential and bronzing issues, but I cannot vouch
for this.

Art
 
OK so your not a polite person :) I must beg to differ with your last para,
I would ask what other manufacturer has introduced a gloss cart to get rid
of Bronzing, I must also beg to differ regarding the 2400 I have seen with
Epson glossey paper slight evidence on Bronzing infact I have an A4 glossey
photo in front of me and it shows Bronzing, OK it's only very slight but
it's there, it's not a differential whatever that means it's classic
Bronzing. We are talking photo quality here, if this had come from my Pro
Labs who handle my film work it would have been sent back, I fully under
stand the process in printing from film to paper is different from using
ink. My point is the end product should be the same, that's the photo.
 
I would ask what other manufacturer has introduced a gloss cart to
Click to expand...
get > rid of Bronzing


Actually, HP has. Check this out:

http://h10010.www1.hp.com/wwpc/us/e...4199-69422-69422-3192780-3192804-3192805.html

Whether it is to "get rid of bronzing" or to even out the gloss levels
is questionable, but HP is using it with their pigment ink set.

There are also new precoats being offered with some inksets to improve
ink color and lessen dot gain on non-inkjet papers. The issue with
inkjet is that it is still in an evolutionary process. It took almost
100 years for silver halide photography to work out quality color
images, so it is demanding quite a bit for inkjet technology to perfect
the process in less than 20 years.

Does the process still need improvement, yeah, but that's also why so
many ink set get created.

Art
 
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