Digital BW, The Print

Adrian,


>... Im looking for some suggestion on minimilizing metamerism. 
>I printing black and white images on a epson 1280 using premium 
>glossy photo paper and matte heavyweight paper. 
>Im currently printing straight RGB, I have toned prints in the past to 
>deal with the color shift, but I would like to print a particular 
>project without toning. ...

Metamerism is caused by the a print having an uneven spectral response -- a
spectral curve that has some lumps in it.  When one makes a grayscale image
from a color inkset, these are inevitable.  Even if the RGB values are the
same, light sources are not entirely even or equal in their spectral
characteristics.  It's the "lumpiness" of the light source interacting with
the lumpiness of the prints inks that causes the "gray" tones to look
different colors under different lighting.

The eyes are much more sensitive to changes is hues in a neutral print than
in one that has substantial color.  So, this problem affects B&W prints the
most.

The way most of us avoid serious problems is to use B&W inksets where the
image is composed predominantly of carbon, not color pigments or dyes.
Epson chose essentially the same (partial) solution with the UltraChrome
approach of running a light black ink up into the shadow tones where the RGB
values are the same.  One might also minimize metamerism by having more
colors in an inkset.  The resulting grayscale spectral curve might then have
more but lower lumps in it.  The R800 comes to mind.

Paul
www.PaulRoark.com