Specifications

On most models, sliding controls on the scanner are used to determine the resolution (dpi) used for
scanning, along with the brightness of the scan. Black-and-white scanners also have a switch used for
line art or dithered scans (dithered is used for photos).
Interfacing a Hand Scanner to Your Computer
Early-model hand scanners used proprietary interface cards that often required an IRQ, a DMA chan-
nel, and an I/O port address to work, but more recent models use either the parallel port or a dedi-
cated PC Card (PCMCIA) interface for installation.
At least one vendor (Essex Portable Computer Solutions at
www.goessex.com) is currently distributing
a hand scanner for portable computers that interfaces through a dedicated PC Card (PCMCIA) con-
nection. Artec’s hand scanner can be interfaced through either a dedicated adapter card or a parallel
port with optional adapter (
www.artecusa.com).
Benefits of a Hand Scanner
■ They have a low cost. Hand scanners, because the user provides the “motor” that moves the scan-
ner, have very few moving parts and thus cost little to make or purchase. They have been the
first scanner for many users.
■ They’re portable. When the parallel-port connection replaced the dedicated proprietary interface
card, the hand scanner became a truly “universal” device that was capable of working on desk-
top or notebook computers with parallel ports.
■ You can scan a book without breaking it. Hand scanners can be used to scan books whose bindings
won’t permit them to be scanned with ordinary flatbed scanners. Because only the page
scanned needs to be flat, this minimizes strain on old and rare books and makes the scanning
of pages from bulky volumes possible.
Drawbacks of the Hand Scanner
■ The user as motor. The number one problem that virtually all users of hand scanners have is the
difficulty of getting a straight scan. Early models made keeping the scanner going in a straight
line virtually impossible because they required users to keep a button on the side of the scanner
pressed to keep the unit on. Although later models made the button a toggle, the amount of
wavy scans that were discarded was colossal. Some vendors even introduced scan trays with
guides to help scans be straight. This helped but worked directly against the portability and low-
cost nature of the scanner.
Even when improvements in scanner design made getting a straight scan less than impossible,
the movement away from a dithered black-and-white image (mixing small dots to produce the
illusion of gray tones) toward true grayscale and then color meant that scanning speed became
more critical. Countless users had to rescan color photos again and again because their attempts
to get 300dpi scans meant their hands were quicker than the mechanical “eye” they were push-
ing.
■ The picture is bigger than the scanner. The second major drawback of hand scanners is their built-
in size limitation: A photo of about 4” wide was all they were designed to scan. Although later
models of hand scanners came with “stitching” software designed to enable two or more over-
lapping scans to become a single final image, this method sounded better than it actually
worked.
Hand scanners are virtually obsolete today for most uses, although notebook computer users who
must travel might find that a hand scanner that interfaces through the PC Card or parallel interfaces
could be a useful tool for image and text research.