Re: Harold K. Vollrath


I can agree! Recently we needed 4" letters of the "Empire Builder"
logo for repainting the John McLaughlin at IRM. I was able to scan an
8x10 Pullman builder's photograph on two scanners but ran into
problems. At 600 dpi you had 3/8" digital pixel bits noise in the 4"
high letters and at 1200 bpi had 1/2" focus and grain error,
fortunately good enough for Bob Kutella to eye ball for his ponce
diagram. This is an enlargement of roughly a factor of 100. You bet
I'm going to order the book referred to here! As a crossover person
from the analog to digital era, I can appreciate the frustration. At
the IRM Pullman Library we scan all b&w negatives at 600 or 1200 dpi
grayscale partly due to memory and printer requirements, unless
required to do otherwise for printed publication. You have to realize
that it is very important in digital printing that sometimes the
scanner and the printer have to be capable of the same resolution,
otherwise you get a peculiar digital error that looks like
herringbone, etc. At the IRM Pullman Library, we prefer to send out
the 8x10 negatives (sorry, for passenger cars)for wet process
printing but can supply the digital prints or CD's(with caveat not to
be used for digital distribution, ie nothing on Internet etc). I had
supplied a scan of a troop sleeper print for B&O RR Museum repainting
and had no trouble enlarging the printing on the trucks to full size.
So a lot of it has to do with the original photographer's skill, the
focus during his printing, and the current abilities of the scanner.
My two bits.
Ted Anderson, curator, Illinois Railway Museum's Pullman Library

--- In STMFC@..., Tim O'Connor <timboconnor@...> wrote:

An important factor in pulling detail out of shadows is
the scanner's "dynamic range". You can find inexpensive
scanners now with a DR above 3.2, which is very good. But
note that DR claims can be deceiving --

Tim O'Connor

At 1/18/2008 01:38 AM Friday, you wrote:
I take your points Rufus, My comment arises from my experience
prints - and scanning them at very high resolution to identify
tiny details
in the background - often freight cars in a yard of interest. I
have found
that a 30 or 50 year old black and white print will provide a lot
information when blown up that way than will the typical 8x10
print I buy
from the local archives. I suspect that is simply because they
scan at 300
dpi, and it isn't sufficient for those tiny details....

Rob Kirkham

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