[Fwd: Re: Metamerism vs Color Constancy]
[Fwd: Re: Metamerism vs Color Constancy]
- Subject: [Fwd: Re: Metamerism vs Color Constancy]
- From: Ernst Dinkla <email@hidden>
- Date: Mon, 26 Sep 2005 13:52:13 +0200
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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