Digital BW, The Print

Cool, thank you.
Tyler

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Carl Schofield
<scho@m...> wrote:
> Daniel & Tyler,
> 
> Here are some spectral plots (eye-one measurements) for a 50% gray 
> patch printed with an Epson 2200 (UC inks) using the Epson driver and 
> neutral, carbon, and sepia QTR profiles.  The spectral distribution of 
> the QTR pure carbon 50% gray (K + LK) is smooth and the added LM + LC 
> in the neutral QTR 50% gray and LM + Y in the QTR sepia 50% gray 
> introduces some variations in the spectra, but not enough to cause 
> visible metamerism.  In contrast, the Epson driver gray is highly 
> metameric and the spectrum exhibits sharp fluctuations in spectral 
> intensity.  The x axis in the plot should read wavelength in nm and not 
> epson driver.
> 
> http://homepage.mac.com/scho/spectra.jpg
> 
> 
> On Friday, September 17, 2004, at 09:53  PM, Daniel Staver wrote:
> 
> > Carl,
> >
> > If you print a picture with a deep blue sky using UC inks you'll
easily
> > see a shift from purplish blue to cyan if you move from fluorescent to
> > daylight. This is consistent with the shift you would see with a
> > "neutral" print printed with the Epson driver. This could indicate
that
> > either the cyan or the magenta inks (or both) are the cause of
> > metamerism, not yellow.
> >
> > --
> > Daniel Staver
> > http://daniel.staver.no
> >
> >> I agree that the "yellow ink causes metamerism" hypothesis is
> >> unverified and probably false, but it would be difficult to test.
> >> Metamerism is most apparent in neutral prints so if one created a
> >> series of neutral profiles with increasing amounts of yellow added it
> >> would be necessary to also add increasing amounts of cyan and magenta
> >> to maintain neutrality.  At some point the neutral grays would become
> >> metameric, but does the metamerism occur because of the additional
> >> yellow ink or the CM?  I suspect it is the latter but I'm not
sure how
> >> to set up a test to confirm this.  Sepia prints I've made with 
> >> profiles
> >> that use only K,LK, LM, and Y do not appear to be metameric but they
> >> are of course also far from neutral.
> >
> >
> >
> >
> >
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