Digital BW, The Print

Metamerism is a pehnomenon where two samples match exactly under one 
lighting source, but when viewed under lights with a different spectral 
curve, they look different.  So, if your print looks great in daylight, 
but you get some weird shifts or crossovers in fluorescent or 
incandescent lighting, metamerism is rearing its head.  Dyes and 
pigments can sometimes have peaks when their molecules are excited by a 
specific part of the visible spectrum.  Some inks are more metameric 
than others (and pigment inks are more prone to metamerism than dyes).  

Since prints are nothing more than reflected light, your overall 
coloration will inevitably change somewhat depending on the light 
source used to view them.  Ideally, there will be no such shift and 
your prints will just appear a little warmer when viewed under a warmer 
light source.  

From my experimentation, I have found that the yellow ink in the Epson 
UC inkset is the most liely to do weird things under different lighting 
situations.  So, I try to eliminate or at least reduce the amount of 
yellow in all my profiles.  This reduces metamerism significantly.

A RIP like QTR or IJC/OPM allows you to build a profile that is 
neutral, has minimal metamerism, is linear, and has the best Dmax a 
paper/ink combo can deliver.  

Lou

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "njms200" 
<njms200@y...> wrote:
> Thanks...I took a look at that info and it was helpful.
> 
> I also printed a few photos on luster paper.  When I first saw them, 
I 
> was stunned by the quality.  Then I turned a photo a few inches and 
it 
> turned purple!  Is that what you refer to as metamerism?  Is there a 
> solution?