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Scan a good deal

Scan a good deal

Over the past few years, scanner prices have fallen dramatically. Once the preserve of high-end print production houses, fast, accurate devices can now be picked up for the price of a couple of theatre tickets. However, this is not due to lack of demand - even in the age of the digital media, there is little sign of a decline in the popularity of the scanner.

As well as being the cheapest and easiest way to get photos onto a PC, a scanner can also be used as a photocopier or fax machine. With OCR (optical character recognition) software often bundled with scanners, they even promise to reduce the office paper mountain by digitising it.

Given these disparate roles, it isn't surprising that the scanner market is as fractured as ever. There are three broad categories of scanner user: first-time PC users who need a cheap way of digitising photos or documents; small business users who need a versatile and powerful workhorse; and high-end business and graphics users who need fast, colour-accurate scans.

The mechanics

Nowadays most people associate scanners with flatbed devices, but although this is the most adaptable type, there remains a wide variety of other options targeted at specific markets. They range from high-end 10,000dpi (dots per inch) drum scanners used in print production houses to handheld and sheetfed scanners, which are still popular in the home and office.

Irrespective of the technology behind them, most scanners work in a similar fashion: by reflecting light from the scanning source via a series of mirrors and lenses onto a charge-coupled device (CCD) array. This array comprises a row of optical sensors that detect variations in light intensity and frequency as it moves along the scanning bed, and transforms it into digital data. Sheetfed scanners work in reverse, by moving the source through the static CCD array.

Not all flatbeds use the same method. Contact image sensor (CIS) scanners dispense with the mirrors and lamps of CCD devices and instead employ LED sensors that sit very close to the document. The result is that CIS scanners are much thinner than their CCD equivalents and consume significantly less power. Traditionally, the downside has been poor colour fidelity and limited resolution support - originally CIS scanners were limited to 600dpi. This is improving, though, and Canon's tiny CIS-based scanners, for example, don't suffer from the same colour or resolution limitations.

Optical and interpolated resolution

The most commonly cited scanner feature is its resolution, but there are two types quoted by manufacturers. Optical, or physical, resolution refers to the number of pixels a scanner can capture, in dots per inch. The higher this figure, the more detail a scanner can grab from the source.

Don't confuse this with interpolated resolution, which uses arithmetical algorithms to calculate and create extra dots between existing pixels. This adds no real information to a picture, so its usefulness is negligible.

Bit depth

Bit depth is the number of bits used to describe each pixel in an image. The more bits used, the more colours the scanner can distinguish. Just about every scanner on the market claims to be 24-bit, which represents eight bits per pixel for the three channels (red, green and blue) used when scanning a colour image.

Some scanners can now scan at 14 or 16 bits per channel, which results in 42 or 48-bit images. This doesn't automatically produce better scans, however. Some manufacturers use software to artificially boost bit depth and even those that employ true hardware bit depth can use the extra bits simply to hide noise and extraneous visual artefacts caused by a poor scanning mechanism.

Scanning above 24 bits also dramatically increases file size and lengthens scanning time; the results often aren't worth it, as the extra colours are at the edge of the eye's perception. The fact that most modern displays are 24-bit means you'll invariably never appreciate the extra information captured.

The benefit of high bit depth in quality scanners occurs during scanning. Processes such as altering the colour balance slightly degrade the original image, but by scanning at a higher bit depth, the degradation is less marked.

Density range

Less frequently quoted by scanner manufacturers is a scanner's density (or dynamic) range, which measures the range of tones the scanner can record on a scale of zero to four. For most purposes, density range isn't critical - although it's a good indication of scanner quality. In simple terms, a dynamic range above three is fine for scanning reflective media such as photographs. If scanning transparencies, look for a higher figure.

Interface types

While some scanners still cling to legacy interfaces such as parallel and SCSI, USB (universal serial bus) has become a near-ubiquitous connection standard thanks to its plug-and-play ease of use, and its ability to easily daisychain with other products. Ironically, USB was designed for low-bandwidth peripherals rather than scanners and, if the customer is regularly working with large documents at high resolutions, faster protocols such as FireWire or USB 2.0 are a necessity.

HOME USERS AND BEGINNERS

Even if all customers intend is to scan a few family photos, it's still easy to be tempted by unnecessarily high technical specifications. While optical resolution and bit depth are important, at the consumer level they are often sensibly sacrificed in favour of useful bundled software and usability enhancements. That said, nowadays even cheaper scanners should boast a resolution of at least 600dpi, which is more than enough for same-scale screen display and inkjet printing.

Ease of use, though, is what really determines the value of consumer scanners. One-touch scanning, allowing you to OCR, fax or copy the document by pressing a single button, is becoming commonplace in budget models. Epson's consumer scanners even offer a ‘scan-to-web' button, coupled with Internet space for hosting photos online, which takes much of the work out of sharing photos.

Sensibly, some manufacturers have recognised that home desk space is often at a premium. The Canon N670u, for example, is little bigger than a laptop and its CIS scanning engine draws a tiny amount of power, meaning it can be powered from the PC without the need for an extra power cable.

However, budget scanners won't appeal to everyone. Don't expect the colour accuracy or speed of more expensive devices. Inexpensive scanners almost always use a USB connection, so scan times can be sluggish. The limited optical resolution also means it's unlikely to find transparency or film adapters of any quality in this price range.

Given the low price of consumer scanners, the quality of the bundled software can make a significant contribution to its value: the $539 Epson Perfection 1650 Photo scores high by including a full copy of Adobe Photoshop Elements, which retails for around $245.

BUSINESS AND EXPERIENCED USERS

Scanners targeted at businesses differ from consumer models largely by offering higher resolution support, better software and faster interfaces, including SCSI and USB 2.0.

SCSI, an option with scanners like the HP 7400C, might not be as friendly a protocol for consumers, but its speed advantage over USB means it remains a valid choice for businesses. A better future-proof choice would be the $399 Canon D1250U2F, which boasts USB 2.0 as well as standard USB.

As with consumer scanners, a good software bundle is important, although only a few are tailored for business users. The bundle with the HP 7400C, which sells for around $1099, includes useful Web retailing software and a forms creation tool alongside more predictable graphics applications.

Sooner or later, most businesses will make use of a scanner's OCR capabilities. Some business scanners are built for this. If users are doing a lot of OCR work, it might be worth looking at a scanner that offers an ADF (automatic document feeder) option. This automates the translation of paper to text, but it is unsuitable for quality photo-scanning.

It isn't written in stone that business scanners have to be flatbeds, and some businesses might actually find it more convenient to use another format. For ad hoc scanning of small portions of text, handheld scanners can be useful, although their limited resolution has meant a steep decline in popularity over the past few years.

For small offices with little space to spare, consider an MFD (multifunction device) that combines functions such as printer, scanner and fax machine.

Sheetfed scanners, which drag flat paper through a static scanning mechanism, have a tiny footprint, but the quality of colour scans and the reliability of OCR scanning can be disappointing. It isn't a surprising drawback - as a rule, MFDs and sheetfed scanners don't offer the same scan quality as standard flatbeds, while still charging a premium for the convenience they offer.

Although networking features remain rare, they are worth considering in a larger network environment. Smaller networks can get around the issue by dedicating a single PC to scanning duties.

HIGH-END BUSINESS AND GRAPHICS

Received wisdom has it that dedicated high-end drum scanners are the only sensible option for producing commercial standard scanner output, but desktop devices can supply excellent results and are more than capable of full-colour print output.

Naturally, for the best results users should start by looking for excellent resolution and bit depth - check that the scanner can also export at high bit depths - and, if scanning transparencies, good dynamic range. Scanning at high resolution and bit depth increases the importance of speed, so users will notice a significant speed boost with a FireWire-, SCSI- or USB 2.0- equipped interface. For heavy-duty scanning, USB simply won't cut it.

The higher bit depth also means that transparency and 35mm scanning becomes genuinely useful, rather than the gimmick it is on budget machines. The $700 Canon 2400UF produces good results from negatives and transparencies, thanks to its patented Fare (film automatic retouching and enhancement) correction technology, which removes dust and scratches from negatives superbly. The only drawback is speed: with this option on, it can take nearly 20 minutes to complete a single transparency scan.

The bundled graphics software will almost certainly have to be replaced with something more powerful, but don't disregard the bundled software altogether: Epson's Expression 1680 features SilverFast AI, an excellent image adjustment tool that gives a high degree of control over scans.

Scanning tricks

Compared to many peripherals, the system requirements for scanners are relatively undemanding. However, scanning large images at high resolutions and permanently storing them on a PC will require a sizeable hard disk. Equally, adjusting scans in an image-editing application will make demands on the processor. That said, any Pentium processor faster than 300MHz possesses enough horsepower to scan photographic prints.

The only way older PCs may be caught out is by the shift of scanner hardware to the USB protocol. Older Windows 95 systems (Service Release 2.1 or later) include USB support, but support in Windows 98 and higher is more robust. Parallel port scanners, on the other hand, won't pose a problem, as this interface comes as standard on just about every PC sold. If customers want a SCSI or FireWire scanner, though, they'll need to invest in a controller card for their PC.

However powerful a scanner, it's only as effective as the software that comes bundled with it. Customers should expect to find a Twain-compatible driver, which allows the scanner to understand the commands sent to it by any Twain-savvy application. Almost every image-editing application on the market is Twain-compliant, including the imaging application bundled with Windows.

Most scanner bundles also include a cut-down version of an image editing application, which should offer enough features for basic image correction and organisation. There should also be an OCR (optical character recognition) package to transfer text from paper to PC. If customers are interested in OCR for archiving purposes, it's worthwhile suggesting they upgrade to a ‘deluxe' version; upgrades are not only excellent value, they also permit more accurate layout reproduction and add extra features.

Scanning photographs

For best photographic results, place the image to be scanned as near as possible to the scanner's ‘sweet spot' on the glass plate, where the scan head gives the sharpest results. It's generally in the middle of the scanning bed, away from the edges.

Ê Using the scanner's software, set the bit depth to 24-bit colour and work out the resolution accord-ing to the image's intended use. If out-putting to a monitor, a resolution of 72-152dpi should be enough. For print, increase the resolution to 300dpi. To enlarge the final image, increase the scaling percent-age. The result will rarely be as sharp as the original.

Ë Once in the image-editing application - in our case, MGI PhotoSuite III - final adjustments can be made to the photo before saving it. If archiving the file, it should be saved in a non-compressed image format, such as TIFF or BMP. Compression formats like JPEG introduce artefacts to the image and should only be used where space is of concern.

Image perfection

Every image scanned will need some form of correction. Photographs often require contrast and brightness adjustments, while magazines or newspaper picture sources need descreening to avoid moiré effects. Users can perform fundamental changes, such as contrast and brightness adjustments, during the scan itself. However, it's better to leave detailed picture enhancement to a dedicated image-editing application.

Ê Digitising an image from a scanner source reduces clarity, which has to be put back manually. Adobe Photoshop LE's Unsharp Mask feature allows scanned images to be sharpened.

Ë To bring out the tones flat-tened in a photo, use Photoshop's Levels palette, which shows the number of pixels at each brightness level in an image. Sharpen the tonal range by moving both sliders towards the middle of the graph.

E-mail straight from your scanner

Ê Many modern scanners feature single-click buttons so users can e-mail, fax and copy documents. Pressing the button triggers the fax driver or sends the scanned copy to the e-mail client. Some settings can be altered - but invariably not all - in the scanner's Control Panel.

Ë If a scanner doesn't permit direct e-mail send-ing, go manual. Scan at 100dpi and save as a JPEG. Attach the image file to an e-mail message, limiting the final file size to around 100KB.

Using a scanner to archive

Ê OCR software is useful for digit-ising paper-based documents. It uses complex algo-rithms to decide where the text lays on a page, and works out each letter based on programmed or learned values. If scanning in greyscale mode, recognition levels are usually better than when using full colour modes.

Ë Once the page has been scanned and recognised, save it as one of a number of text file formats. Subsequent scanned pages can be automatically added to the text file to create a complete report.

Sharing a scanner across a network

Ê If a scanner lacks dedi-cated sharing software, users can designate a folder on the PC connected to the scanner as the default download location. The second PC then copies the scanned files. To activate a shared folder under Win XP, use the Network Setup Wizard.

Ë In previous versions of Windows users have to enable file sharing from the Network Control Panel. Go to Start-Settings-Control Panel-Network. Click on the Configuration tab and select ‘File and printer sharing for Microsoft Networks'. In the resulting box, choose ‘I want to be able to give others access to my files'.

This feature was compiled in conjunction with ARN's sister publication PC World.


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