Digital BW, The Print

Yes, and quite interesting in terms of interpreting color intent in historic 

paintings. 

-- Indeed.



 papers with artificial brighteners may look quite similar to non-brightened papers in 

lights low in UV and low in blue (such as tungten and other incandescents) ; 

but the same papers compared under north light look REALLY different, due to 

increased blue light (and if the glazing isn't UV resistant, from increased UV 

components exciting the brighteners as well).

-- Now that's a really interesting point. I find the whole uv brightener thing annoying. But I never thought it through to the evaluation issue. I do think it's ironic that uv brighteners are (often) added to paper and then we do everything we can to keep uv away from the paper...

Thanks!

----- Original Message ----
From: "CDTobie@..." <CDTobie@...>
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Sent: Tuesday, January 30, 2007 12:39:14 PM
Subject: Re: [Digital BW] Re: Light source for evaluating prints?









  


    
            

In a message dated 1/30/07 1:27:20 PM, evogel@flash. net writes:



> Thanks David. Wasn't really suggesting (cold) north light as a good source 

> for these purposes, but it is significant historically.

> 



Yes, and quite interesting in terms of interpreting color intent in historic 

paintings. It has a factor more directly related to this list as well: papers 

with artificial brighteners may look quite similar to non-brightened papers in 

lights low in UV and low in blue (such as tungten and other incandescents) ; 

but the same papers compared under north light look REALLY different, due to 

increased blue light (and if the glazing isn't UV resistant, from increased UV 

components exciting the brighteners as well). This factor is often confused 

with illuminant metamerism; but its not actually related. So I tend to note 

"illuminant metamerism and OBA excitation" as a pair of factors, but no one seems 

to 'get' the second one, so perhaps we need a more easily understood name for 

it...



C. David Tobie

Product Technology Manager

ColorVision Business Unit

Datacolor Inc.

CDTobie@colorvision .com

www.colorvision. com



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