Digital BW, The Print

Can someone help me interpret these numbers?  Or point to a resource to  
help me understand what is being said.  I would like to understand:

1) What is being measured when and estimate of 54 years is made.  Is  
that density, or color shift, or some proprietary combination of  
measured attributes.

2) In light of the answer to question one above, at what point in  
measuring that attribute did the print no longer last.  I mean if the  
average of the samples was 50 years, what was the attribute change at  
50 years?  10% change, a 'noticeable' change? or something else.

3) Does the tester assume a linear continuance of the change in that  
measured attribute. Is that reasonable to assume.  For example if the  
measurement changes 5% in 3 months can you extrapolate that using a  
linear equation to 50 years?

4) How intense is 50 lux.  Would that be a 'normal' viewing  
environment. Is there a linear relationship between fading and light  
intensity.  For example, is 50 lux for 300 days the same as 500 lux for  
30 days?

5) Do all of Wilhelms' test results use the same test criteria and test  
setup?  Are test results for company A using the same framing (glass),  
light source, humidty etc as the testing for company B.

There is, obviously, a lot I don't know about this testing and the  
results.

Thanx

Kevin Gulstene
On Tuesday, October 29, 2002, at 06:48 AM, Sam A. McCandless wrote:

> Wendel White's promotion of civility on the list is very welcome to me.
>
> Wendel's e-mail address intrigued me, so I visited his web site
>
> http://blacktowns.org/
>
> and found a nicely-done site about his interesting project
> documenting small-town African-American life in Southern New Jersey
> with B&W photos. Made me wish I could see the associated Noyes museum
> exhibit in New Brunswick (without traveling 3000 miles to do it).
>
> As for Marc's take on Wilhelm, despite Wilhelm still being "AWOL" as
> far as we (if not his clients?), are concerned, Wilhelm still has a
> lot of credibility with me. I do wish his (and RIT's) clients would
> publish more of the results of their testing. Maybe even _before_
> they start to sell the products tested!
>
> Marc is right about Wilhelm's 54-year and other preliminary "point"
> estimates: they are misleadingly precise. And I wish Wilhelm would
> report them as the midpoints of ranges which are two standard
> deviations wide. But if for some reason he can't, I'd rather have 54
> than, say, 50, along with the inaccuracy associated with rounding
> error. Of course, the 54 itself is presumably the rounded-off average
> of an appropriately-large number of samples - but I wish we knew how
> many.
>
> Wilhelm's clients might, however, think - largely with good reason I
> suspect - that, unlike me, most consumers of Wilhelm's data have
> little appetite for statistics, know that estimates are estimates,
> and make allowances for that. And since Wilhelm's clients - not we -
> are paying for the work, who am I to complain? Well, I am _their_
> client. So I feel entitled to complain - but about what those clients
> do (mostly don't do) rather than about what Wilhelm does for them,
> which I expect is done to a relatively high standard. I think we
> should focus our criticism on his clients' marketing.
>
> Sam McCandless             samcc@...
>
>
>>> From: Marc McCarron <mamccarron@...>
>>> Reply-To: DigitalBlackandWhiteThePrint@yahoogroups.com
>>> Date: Tue, 29 Oct 2002 01:28:56 -0500
>>> To: DigitalBlackandWhiteThePrint@yahoogroups.com
>>> Subject: [Digital BW] Wilhelm Imaging Research
>>>
>>> Screw Wilhelm Imaging Research.
>>> What credibility does Wilhelm have with his no show on the Web for  
>>> the last
>>> 2 years ?
>>> 54 years for Semigloss? why so inexact? can't he give us the days  
>>> and hours
>>> while he's at it?
>>> Vilhelm, ve need someone else to lead the vay.
>>
>> Here is another way to look at this issue. I usually just say 'thank  
>> you'
>> when someone gives me something for free (whether it is information  
>> or a
>> nice piece of pie) and if I don't like it, I just quietly through it  
>> away.
>>
>> Wendel
>
>
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