Re: [Fwd: Re: Metamerism vs Color Constancy]
Re: [Fwd: Re: Metamerism vs Color Constancy]
- Subject: Re: [Fwd: Re: Metamerism vs Color Constancy]
- From: <email@hidden>
- Date: Mon, 26 Sep 2005 09:12:08 -0400
Ernst,
Interesting extension of the discussion. Let me digress
even more...
The "black and white" case is a world in itself. Because
of lower cost measuring instruments that enable almost
everyone to characterize color phenomena, there is a
tendency to search perfection. We could not measure these
differences in the past, so we placed less attention on
them.
Metamerism is the basis of photographic color reproduction
and always produced results with more or less variability
relative to the original objects. B&W also always existed
in many flavors, with some papers hotter, colder, or
browner than others (not to mention contrast range and
sharpness), with the more adventurous looking into
"bromoils" and "bichromated gums".
It is true that most of the old films and papers can now
be simulated by software and that insuring a neutral
output is just a way of calibrating the modern virtual
darkroom. However, at some point, having some metameric
inconsistencies should only be viewed as a fact of life.
Like in the old days, if you did not like a certain Kodak
paper, you would go for an Agfa one for certain jobs. This
would translate now in using a third party ink with a
third party paper on a given printer.
A problem with all the available solutions we are offered,
is finding the best one for our taste and requirements.
This takes lots of time and work, two concepts that are
apparently incompatible with the pressure of the modern
world.
Danny Pascale
dpascale AT babelcolor DOT com
www.BabelColor.com
On Mon, 26 Sep 2005 13:52:13 +0200
Ernst Dinkla <email@hidden> wrote:
email@hidden wrote:
Just imagine that you have the same color from two
sources (ink and
paint for example); if they both show the same color
inconstancy under
two given illuminants, they could well be metameric
matches... (for some
illuminants, maybe, but not garanteed!).
Are N-Color inkjet systems like the Epson R1800, some
Colorspan models, the Roland Hexachrome actually better
or
worse in metameric matching if compared to CMYK printers
based
on the same pigment or dye inks? If restricted to art
reproduction with its more limited pigment variety?
There are several ways (hue angle, saturation, sometimes
selectable) to use the extra hues in the RIPs that drive
the
CMYKORGBetc printers and I would expect that that also
influences the results.
The answer may be found at the other end of the scale,
in
monochrome printing. The K3 Ultrachrome set and the
variety of
Quad pigment inks available should at least be better on
metameric matching when reproducing B&W graphic art +
drawings
due to the corresponding use of carbon pigment in many
originals and the inkjet printing inks. Except where the
originals are based on pigments derived from metals like
lead,
iron, silver or more exotic like dyes from plants. But
even
the resins used in inks, paints, pencils, pen ink etc
will
influence the match so I doubt that the few hues extra
in
N-Color systems will improve matching much.
It's interesting to see that the dye based Lyson B&W
quad
inksets (not just the Small Gamut) had much more
metamerism
reported than the pigment quad inksets available today.
Probably a physical reason for that, more transparency
in the
dye inks + the influence of OBA in the paper coating.
Another
observation is that in digital B&W printing for
photography
this issue is as much discussed as in color printing.
The
monochrome image sets its own standards for what is
acceptable
in hue shifts in changing light conditions. With less
variables in the print the more attention is given to
subtle
changes within that limitation. So Delta E becomes
relative.
In the B&W discussions it is harder to grasp what is
meant,
the degree of metameric matching to analogue silver
prints or
the different ranges of color inconsistency under given
illuminants.
--
Ernst Dinkla
www.pigment-print.com
( unvollendet )
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