[PADG:1785] 8/15 Diginews--Steve Chapman Article

[kristin alana baum <kristin-baum@xxxxxxxxx>]

Regarding Chapman's article "Book Scanners and Cradles: Links to
Products and Reviews," we at the University of Iowa Preservation
Department have explored an additional option to the traditional use of
the 180 degree cradle design of the Minolta PS7000. This option
emphasizes the important role of hand manipulation in top-down scanning
as well as perhaps a greater versatility of the Minolta PS7000 than is
suggested by Chapman.
Discussion of cradles for overhead scanning of bound items should include
an obvious option: that is, hand cradling. Hand cradling methods seem
particularly suited for tightly bound, oversized items when placed on the
easel in a landscape orientation with
the foredge against the back gauge (instead
of the head against the back gauge). This orientation permits
non-damaging production paging at little more than a 90 degree
opening.
Two passes are needed; one for rectos and one for versos. For efficiency
and accuracy, all recto pages are scanned, followed by a scan series of
the verso pages. This option works well if the scanning interface that
you use allows for incremental page/file numbering by 2 (e.g. 1, 3, 5, 7,
for recto and 2, 4, 6, 8 etc. for verso), which insures the operator
maintains the proper page sequencing.   With regards to
handling in the recto pass, the back cover of the book rests on the bed
and individual pages are lifted from the text block (into a vertical
position).  In the verso pass, the front cover of the book rests on
the scan bed and individual pages are released to the horizontal plane of
the scan bed (from the vertical position). The whole process is under
very delicate control with the hand held support and finger paging of the
operator. Very subtle manipulations induce flatness in the page surface
to be scanned. The foredge orientation is also particularly suited to the
Minolta fixed lighting array (e.g. page cockling seems less disruptive to
the scan).
Of course, this scenario of hand cradling, poses additional
considerations for image processing: all recto page images will require a
90 degree rotation clockwise, and all verso page images will require a 90
degree rotation counterclockwise.  This image rotation may pose
addition considerations regarding the pitch of the raw images in relation
to one another as well as possible variances in edge clean up. 
Regardless, these additional considerations have not added significantly
to the time required for scanning and processing such a book.


_________
Kristin Alana Baum
Assistant Conservator
University of Iowa Libraries
100 Main Library
Iowa City   IA   52242-1420
319. 335.5503  
kristin-baum@xxxxxxxxx
http://www.lib.uiowa.edu/preservation/
http://www.lib.uiowa.edu/conservation/models/