Digital BW, The Print

Eric Vogel wrote:

>I am curious to know: what are spectral scan and printing methods?
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Several methods: Measuring the paints with spectrometers and adding that 
to the information gathered with advanced digital photography or 
scanning.  Monochrome sensor with several (up to 13)  narrow band 
filters to get a better spectral representation of the pigments used in 
the painting.
The printing part is more an abbreviation for what is used in practice: 
printing with more hues or what they call N-color systems. For example 
the Epson R800 is a mild version of that, CMYKORGB the practical 
maximum. N-color printing should reduce differences in metamerism 
between the original and the reproduction as the pigments between the 
two are more related in color. I guess there's still metamerism possible 
as oil based pigments in paintings behave differently to for example the 
water based pigments of inkjet printing. Not to mention the use of toxic 
pigments in the past and today's less toxic artificial pigments that 
have to be used.

For musea having the actual digital-spectral information at hand is 
important in relation to restauration and archiving needs.

N-color and multi-spectral art reproduction will give some hits in Google.

http://www.ichim.org/jahia/webdav/site/ichim2004/shared/static/images/salon%20pro/06_LumieresTechnology_fichier01.pdf

http://www.art-si.org/PDFs/Processing/ICOM05_Berns_Seurat.pdf

The last more specific for the Seurat painting and describing the aging 
of the pigments and the loss of luminosity as a result. A digital 
reproduction of the original painting like it was when first shown in Paris.

Not that I understand all of it :-)

Ernst