Re: Subject: photogravures
Re: Subject: photogravures
- Subject: Re: Subject: photogravures
- From: "Tom Lianza" <email@hidden>
- Date: Tue, 23 Oct 2001 09:08:15 -0400
Hi All
David Wollmann wrote:
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I must be seeing the effects of
metamerism because the prints look one way in my viewing
both, other way under tungsten, fluorescent and still
different in daylight.
I have not experienced this with my color prints only these
monotone gravures, does this sound like metamerism?
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There seems to a consistent misunderstanding about metamerism that seems to
run through the ink jet industry and then get reinforced by some
contributers to this group.
What David is seeing is precisely what Leonardo daVinci recognized in the
15th century: The color of an object is effected by the color of the objects
that illuminate it.
David comments that he doesn't see such a difference with his other images,
printed using the same inks. This is a very nice illustration of the
priorities of color reproduction that Dr Robert Hunt outlined in his book
"The Reproduction of Color". At the top of his list is overall hue. The
sepia tone found in the images is difficult to maintain because its average
chromaticity lies relatively parallel to the white point locus. As we
change the correllated color temperature of the white we see that relative
distance between the sepia color increase as we move towards daylight and
change angle. This is a simultaneous change of "colorfulness" and hue.
Epson inadvertantly did the ink jet industry a disservice when they used the
word "metamer" in describing differences between the dye based and pigmented
inks. While there is no question that there is plenty of room for potential
metamerism, the biggest problem with pigmented inks lies in their opacity.
The resulting combinations of the overlays results in significant native
differences in the basic hues of the reproduction process and the gamut.
The combination of these factors make it very difficult to get the same
image on the two different media (an Epson 1280 vs. the 2000p) to match
under the SAME illuminant (the definition of a metameric match). The poor
photographer is left with two choices: a high gamut image with marginal
lifetime or a marginal gamut image with long lifetime. For the person doing
proofing, I don't think that there is a choice. It makes no sense making a
proof that can't encompass the gamut of the final reproduction. In my own
work, I use Generations Inks on an old Epson 1200 and I use Lumijet Classic
Velor or Soft Suede papers. The gamuts of these processes don't really
compare to a type C print, but they do work well when viewed at high
luminance levels. On the other hand, the tonal range seems to exceed what
can be achieved in the C print, so there are always compromises.
Tom Lianza
Technical Director
Sequel Imaging Inc.
25 Nashua Rd.
Londonderry, NH 03053