New subject: [Commons-l] Digitisation equipment

29 Aug 2009


      Gregory Maxwell wrote:
...
For digitizing what?
Exactly, that's the first question.
...
Archive.org digitizes books using a pair of canon 1Ds (? perhaps 
it was a 5D? In any case the 5DII would be sufficient now) on a 
custom stand with a hacked up copy of gphoto2 to actuate the 
cameras.
That's Brewster Kahle doing things many years ago (2002? 2003?). 
Today, a much cheaper low-end digital SLR, or even compact cameras 
will give you the needed 10 or so megapixels.  But again, if you 
need to pay your staff, a ten times more expensive camera might 
easily pay its own cost in increased speed, or increased shutter 
lifespan.
...
I'm not sure how they're dealing with curvature (I think they 
just may lay a glass plate on the pages), but it would be easy 
enough to solve using a laser pointer with a pattern generating 
holographic grating and a second exposure to capture the page 
distortion and some fairly simple software processing after the 
fact.
The Internet Archive apparently uses a fixed glass, and lowers the 
book cradle to turn pages, http://aipengineering.com/scribe/
Other designs have a fixed book cradle and lifts the glass, e.g. 
the Atiz DIY, http://diy.atiz.com/
I thought the Internet Archive design was very clever, since it 
keeps a fixed distance from lens to book surface (beneath the 
glass), until I saw the bkrpr.org where you just lift everything. 
That's a design for 2009! I haven't tried to build one myself yet.
----
However, you can capture lots of books (that can be opened fully) 
with a single camera, laying the book flat on a table with a glass 
on top.  That's just like a flatbed scanner (but much faster) 
turned upside down.
In January 2008, I used a 10 megapixel Canon EOS 400D (Digital 
Rebel XTi) with a 50 mm lens to shoot this, laying flat on a table 
under a glass, http://runeberg.org/stridfin/0226.html
On that webpage, the image is reduced to 120 dpi (1.2 megapixel), 
but the original is 300 dpi (7.5 megapixel).  The map shown is 
reused in http://en.wikipedia.org/wiki/Battle_of_Alavus
That's an example of how one specialized book can be very useful 
for a limited Wikiproject. This book was published in 1909 for the 
100th anniversary of the Finnish War (1808-1809), and digitized in 
2008 for the 200th anniversary.
-- 
  Lars Aronsson (lars@aronsson.se)
  Aronsson Datateknik - http://aronsson.se

  Project Runeberg - free Nordic literature - http://runeberg.org/

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