Prices of scanners have fallen dramatically, making them available
to a wider audience. But which technology should you invest
in?
The price for scanners has fallen dramatically. A few years ago,
a 24-bit, true-colour flatbed scanner easily could have cost a cool
£2,000. Today, you can find one for as little as £400. Under £1,000
scanners abound, many capable of scanning at ultra sharp
resolutions that not long ago were out of reach of anyone but
well-heeled graphics professionals. Almost all units come with
capable image-editing and Optical Character Recognition (OCR)
programs. Many can be equipped with optional sheet feeders and
slide adaptors to speed up document processing and turn
transparencies into digital images.
Scanner installation and operation are smoother nowadays, thanks to
TWAIN drivers, which lets you scan material from within many
Windows applications, and colour-management systems, which
automatically adjust colours so that what you see on your monitor
will match what comes out of your printer. Moreover, with Windows
95 and its Plug-and-Play specification, scanners should be even
easier to get up and running in the near future.
Scan this, scan
thatThough most scanners perform worthy double and triple duty
( scanning a page of text one moment, a piece of line art the next,
a photo after that ( it's smart to start your decision process by
deciding which task you'll perform most. That will keep you from
spending money for functions you really won't need.Scanner choices
may seem complicated; some manufacturers offer a dozen or more
models or configurations. Nevertheless, there are really only three
variables to consider. First, do you want a handheld scanner, which
you drag over an image manually, or a flatbed? Second, do you need
a colour-capable scanner, generally a 24-bit device that can
produce theoretically 16.7 million colours, or a greyscale unit
limited to 256 shades of grey? And third, do you need high
resolution capability of 600 dots per inch (dpi) or more, or will a
400 dpi or lower resolution scanner suffice?For occasional scans of
small pieces of paper or small portions of a page, a handheld
scanner makes the most sense. Handheld scanners' most compelling
quality is their affordability - 256 greyscale models are available
for less than £70 direct, with colour units available for about
twice that.They come with utility software for stitching together
multiple strips or passes over wide images; though stitching
software often works surprisingly well, the process is too slow for
any kind of volume. Moreover, handheld scanners are being crowded
out of the market, in some instances, by a new crop of compact
desktop models, equally handy for occasional digitising and
superior OCR and document-processing work. If you're recruiting a
scanner primarily to import photos and other artwork for publishing
purposes, you'll want a flatbed model. Don't overbuy, however.
Match the scanner's resolution with that of your intended output
device. If you'll be digitising photos for later printing on a 600
dpi monochrome laser, for instance, you'll be satisfied with a 600
dpi greyscale scanner. A higher resolution colour scanner makes
sense for prepress colour separations or enlarging scanned images
such as small photos or 35mm slides.If text import via OCR software
is your top concern, you need not worry about high resolution or
colour. Shop for an affordable greyscale scanner that has a top
notch OCR package bundled with it. That said, remember that while
you may not need colour now, you may in the future. With colour
printers' prices falling and resolution rising, the newsletter you
print on a monochrome laser today may come out of a colour inkjet
tomorrow. Since price differences between identical resolution
greyscale and colour scanners are as low as £200, it can be smart
to pay the extra amount now rather than buy a new colour scanner
later.
One if by handOnce the only choice for scanning on a
budget, handheld scanners have been pushed into the bargain
basement by the declining price of their full-page, flatbed
cousins. Even so, they still fill a useful niche. Like their
flatbed cousins, handhelds combine a light source with a charge
coupled device (CCD) that reads the reflected light intensity and
converts it to digital information. Rather than use a motor to move
the scanning hardware past the image, a handheld scanner depends on
your muscle power. That's a disadvantage, since few of us can drag
a peripheral across a page as smoothly as a machine can.Also,
because handhelds scan such narrow three to four inch strips,
you're either limited to small images or skinny columns of text, or
you're at the mercy of the software used to stitch together
multiple scans. Make sure a handheld scanner comes with stitching
software before you buy. Ask, too, if the scanner/software
combination can warn you when you're moving the scanner too
quickly, causing it to skip part of the page or image.On the
positive side, handheld scanners are easy to install ( most plug
into a PC's parallel port, making it easy to move the scanner from
one system to another or to carry one with a laptop PC. You'll find
greyscale and colour capable handheld scanners with resolutions as
high as 400 dpi. It's difficult, however, to perform accurate hand
scans at resolutions above 200 dpi, since the higher the device's
resolution, the slower and steadier your hand dragged path must be
across the image.
The mainstream choice: flatbedsThe
advantage of flatbed scanning is clear as soon as you start
scanning even a short stack of documents or images. Slap down the
paper, close the lid, click on your software's Scan icon or press a
key, and the CCD moves down the length of the sheet. You get a full
page scan in one shot - most of the time.Greyscale scanners need
just one pass of the CCD to finish the job, but when scanning in
colour, many low to mid priced flatbeds make three passes to gather
red, green and blue (RGB) information. A more accurate method ( and
a more expensive one, although its price has fallen over the past
year ( is single-pass scanning. A single pass colour scanner either
uses three light sources almost simultaneously, or separates a
single white light source into the RGB (red, green, blue)
components with a filter.If speed is important ( in other words, if
you make more than a few scans each day ( look for a single pass
scanner and ask the vendor or reseller about different models'
scanning speed. Even at the same resolution and colour depth, some
scanners are quicker than others are.And whichever speed you seek,
ask if the scanner's light source remains on constantly. Some units
don't turn off their lamps between scans, which makes for more
frequent replacement of burned out bulbs. Check, too, on the
availability of add-ons such as automatic sheet feeders for
high-volume OCR work and transparency adaptors for turning slides
into digital images. Most of these can be installed in a few
minutes without any outside help.By contrast, most flatbed scanners
themselves connect to your PC through an included 8-bit SCSI
interface card, so you may have to wrestle with IRQs and address
conflicts during installation and configuration. If your computer
already has a SCSI interface, perhaps for its hard drive or CD-ROM
drive, find out if the scanner uses standard SCSI or some more
exotic variant, then make sure the vendor provides a suitable
Advanced SCSI Programming Interface (ASPI) driver. Some models even
include drivers for use over a network, letting you share a scanner
throughout a small workgroup.
Scanning the rainbowColour
rules. And it's cheaper than it's ever been too. If there's even a
chance you'll want to digitise and then display or print colour
images, get a colour scanner.Scanners' colour capability, like that
of graphics cards, is measured by bit depth. The norm now, 24-bit
colour, provides 8-bits of data or 256 different possibilities for
each pixel in each of the three colour channels: red, green and
blue. That multiplies out to 16.7 million possible colours. Many
scanners aimed at graphics professionals, such as the HP ScanJet
3c, are 30-bit devices capable of more than 1 billion possible
colours. Some, such as Microtek's ScanMaker III, support a still
greater palette ( 36-bit colour.More isn't always better when it
comes to colour depth because it isn't always necessary. A 24-bit
or 30-bit colour image will be wasted when displayed in a
presentation using 256 colours. And, as you'd expect, the more bits
per pixel, the larger the image file. High-resolution, high-colour
images can fill a hard drive in a hurry.And as far as text is
concerned, the most accurate OCR involves not 24-bit colour or even
8-bit monochrome (256 grey scales), but one-bit, black-and-white
scanning. The Avec 140 HomeScan, for example, is a 1-bit, 200 dpi
scanner for line art and OCR that also doubles as a fax machine.On
the other hand, the richer its palette, the more accurately a
scanner can capture an image's shadows and colour subtleties.
Though a 30 or 36-bit scanner can be overkill when you're printing
digitised images on an inkjet, it can work wonders with
transparencies. Colour slides have a much greater range of colour
qualities than images on paper. When fed through a high-quality
scanner with a transparency adaptor, they can produce stunning
images.For most work, though, 24-bit colour is sufficient. Don't
settle for anything less. You really don't have to settle, since
24-bits is the current de facto standard. However, don't pay for
more unless you're sure you'll use it.
Dots and more dotsJust
as you may have 20/20 vision, a scanner might have 400 x 800
vision. Its optical resolution, measured in dots per inch, defines
the sharpness of detail it sees.A flatbed scanner's optical
resolution, also called true resolution, is listed as horizontal
times vertical dots per inch. A 400 x 800 dpi scanner, for example,
divides each horizontal inch of an image into 400 pixels and reads
800 lines of data from each vertical inch. In other words, its
motor takes 800 steps to move the CCD one inch, while the CCD
itself contains 400 light sensitive elements across each inch of
its width.Some 300 x 300 dpi flatbed scanners are available, but
current low-end colour models start at 300 x 600 dpi. The norm
today is even higher - 600 x 600, 400 x 800 and 800 x 400 dpi
devices readily can be found for less than £1,000. The top end of
the general business scanner market is in the 1,200 to 1,600 dpi
range. Microtek's ScanMaker IIHR, for instance, features 600 x
1,200 dpi resolution and sells for about £600. Although higher
resolution scanners produce more accurate digital images, they're
generally slower at scanning. And the image files they produce are
much larger: An image scanned at 600 x 1,200 dpi contains four
times as much data as one scanned at 300 x 600 dpi, so you'll need
plenty of RAM and hard drive space to edit and store such fine
scans.Nevertheless, a high resolution scanner can be a good match
for a high resolution output device. If you're converting greyscale
images for printing on a 1,200 dpi laser, for instance, a scanner
in the 1,200 dpi range makes sense.It's important to note that
optical resolutions aren't the only sets of numbers you'll find in
scanner ads. Most also cite a scanner's interpolated (sometimes
called "enhanced") resolution, which can seem stratospheric. The
800 x 400 dpi Umax Vista S-8, for example, boasts an interpolated
resolution of 6,400 x 6,400 dpi.Interpolation is a software scheme
typically handled by the scanner driver. It can't actually produce
more dots per inch; only the scanner's hardware can do that. But it
can trick the eye into seeing a higher perceived resolution via
averaging, which means examining adjacent pixels, then creating
additional intermediate pixels based on that data. The results
include smoother transitions in greyscale images and better quality
colour in colour scans.Interpolation has no effect on 1-bit images,
since those pixels are either black or white with no shades of grey
in between, and it isn't always a benefit. Some high contrast
images can be interpolated into muddy greys and drawings with
sharply defined lines can end up looking fuzzy and indistinct.
Still, it's a valuable bonus. Look for a scanner that can generate
interpolated resolutions of at least 1,200 x 1,200
dpi.
Multifaceted multifunction productsSmall offices where
desk space and budgets are equally tight are increasingly turning
to multifunction peripherals that combine scanning, printing,
faxing and copying capabilities. Available from vendors ranging
from Brother and Lexmark to Panasonic and Xerox, these all-in-one
units typically sell for £800 to £1,000 via mail order.If
consolidation and cost-cutting are paramount, a multifunction
peripheral may satisfy you. But there are trade-offs, particularly
when it comes to scanning. So far, these scanners are exclusively
greyscale, not colour ( with some units limited to 16 or 64
greyscales, though Lexmark's Medley supports 256. Optical
resolution is typically 200 x 200 or 300 x 300 dpi, with Okidata's
Doc-It 3000 claiming the prize at 400 x 400 dpi.Frankly,
multifunction peripherals' scanning hardware is intended primarily
for OCR purposes such as scanning a fax into editable form. Many,
in fact, use the same technology to scan and fax. Multifunction
units may give an office everything it needs in one shot, but the
potential drawback to buying a "jack of all trades" is the risk of
getting a master of none ( a low-powered peripheral that's easy to
outgrow. If saving space is the essential issue, you may want to
consider one of the compact desktop personal scanners from
companies like Plustek instead. Otherwise, with flatbed-scanner
prices falling so sharply, it makes better sense to opt for a
standalone scanner rather than a multifunction device if you
anticipate you'll need to scan more than a few text pages or low
resolution, greyscale images. The key is simply to know your needs
( both short and long-term before you buy.
And all the
restWith such a rich lode of scanners to mine, it's likely
you'll end up with several models on your shopping list. One way to
effectively narrow the field is to evaluate each unit's bundled
software. Few scanners are sold without at least one application;
most come with a pair or more of programs.Look first at the
scanner's TWAIN driver. A specification developed by a group of
hardware and software makers, TWAIN simplifies and standardises the
scanning process, letting you capture an image or begin an OCR
session from within any TWAIN-compliant Windows application. Most
such applications provide an Acquire command in the File menu.Not
all TWAIN drivers are alike, however. Some, such as the DeskScan II
driver included with the HP ScanJet 3c, have extra features. These
abilities include automatic exposure in which the scanner evaluates
the image and sets such things as brightness, contrast and colour
for you, which is highly recommended for business users without
graphics experience. Other TWAIN drivers, by contrast, present
confusing dialogue boxes or seemingly endless menus, and a few
scanners provide no TWAIN driver at all.Many scanners now also have
a colour management system for matching scanned colours with those
you see onscreen and from your colour printer. The process of
colour matching differs among scanners. Some units offer software
controls such as Microtek's excellent Dynamic Colour Rendition
utility. Others provide colour calibration targets for you to scan
and then print. However it's done, some kind of colour management
system is vital for generating colour separations.Beyond their
TWAIN drivers and colour management systems, software bundles
typically include an image editor for manipulating, adjusting and
enhancing the visuals you slap on the scanning glass. It also needs
an OCR package to finish the job of turning paper pages into
editable electronic documents; or both, to make your new scanner
instantly usable right out of the box. Some models come with a
utility that lets you use your scanner and printer together to
create a virtual copier.And some scanners, marketed as document
processors, include a document imaging package in the mix, letting
you put a dent in the pile of paper that threatens to bury most
offices. Document imaging, which combines OCR with organisation and
retrieval tools stolen from enterprise-wide document-management and
routing systems, converts paper to digital data, saves it to your
hard drive, and summons it to the screen as quickly as you can type
search requests.After a document is scanned, its OCR converted text
data is indexed and saved to the hard drive, usually along with a
thumbnail image file of the original document. The finest programs
also let you browse lists of documents ranked by how closely they
match your search criteria. One of the smartest document imaging
package is Caere's PageKeeper, which processes email messages and
incoming faxes, as well as paper-based documents, using Caere's
highly accurate OmniPage OCR engine.Finally, don't be duped by the
quantity of software titles bundled with a scanner. Look for
quality, as indicated by friends' or magazines' recommendations
instead. Many scanners, particularly those on the lower end of the
price spectrum, come with "lite" versions of popular image editors
or other programs, or unwieldy OCR samplers that lack the accuracy
of up-to-date versions. A second-rate bundled application adds
nothing to the bargain if it makes you pay for more powerful
software out of your own pocket.
Scanning, scanning,
scannedThe days when scanners were solely the domains of
sophisticated design shops are long gone. Thanks to steadily
falling prices, more powerful software and higher speeds and
resolutions scanners are taking their place beside many a
PC.Handheld units are facing a slow but sure demise, squeezed on
one side by affordable, high-quality flatbeds, and on the other by
alternatives such as personal scanners. Otherwise, scanners'
prospects have never been brighter. Giving your PC a good pair of
eyes is easier ( and cheaper ( than ever before.
Compiled by
Paul Phillips( Caere Corporation, 1999