Digital BW, The Print

Hi Paul. Along with C D's comments and suggestions, I fear you are looking at spectral deficiencies in the light sources themselves. I'm not sure how you can overcome this. It's just an extended example of printing to match the display conditions directly because one can't have it all. While you might be able to adjust ink formulations to maintain visual (but not instrument measured) neutrality with a particular CF lamp brand or even a range of them, how can you plan for an unknown or later version of such or a different manufacturing run. As for LEDs the spectral distribution is up and down all over the place and very lumpy indeed.Even worse is the fact that different manufacturing runs of LEDs will vary quite significantly so any change at all in lamps or image placement on display could have serious impacts even if you could compensate for a single circumstance.It's extremely doubtful that affordable lighting would be very consistent from lamp to lamp over time either.Reference LEDs must be closely temperature and current controlled if expected to be constant in spectral output.
If you have access to an emission spectrophotometer you can measure the lamps and see what I'm referring to in their spectral curves.

Unfortunately our eyes are extremely sensitive to minute color deviations with truly neutral objects. The best ,if one can call a compromise that, case might be to attempt to adjust the inks such that the lack of constancy bends in a pleasing direction and trust that the physiological aspects of human vision will handle things as well as possible.

There's a lot of work in your task I believe.

Regards,
Duane


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul" <roark.paul@...> wrote:
>
> Metamerism has become an un-expectedly significant issue in my experimenting with glossy neutral printing. I never had to worry about it with the 100% carbon printing approaches. 
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> In addition to the dyes for cards, one significant goal for me is to develop an appropriate glossy medium that can hang near my Eboni-6 matte prints and have them both look good under varying lighting conditions.  
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> The energy-efficient CF and LED lights are major contributors to the problems I'm having reaching this goal.  
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> While I knew the dyes reacted relatively poorly to fluorescent lights, the extent of this metamerism with the older fluorescent lights (CRI 75) surprised me.  They can have a major green/blue/cyan shift. 
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> I have also been surprised by the extent of the metamerism I see in prints made with neutralized carbon plus LC & LM.  There seems to be a significant reddish shift under the new LED lights.  Of course, the more color in the print, the greater the problem seems to be for B&W.
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> Is there an easy way to objectively measure and describe the degree of metamerism?
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> 
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> Paul
> www.PaulRoark.com
>