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There are two worlds out there on the desktop. The first is the digital world, full of the letters, graphics and spreadsheets that you create on your computer and transmit electronically. Then there's the paper world: the "real" letters, photos and other items that people give you or that come through the mail.
Maybe you wish you could turn that 50-page typewritten report into something you can edit on your PC. Or maybe you'd like to fax a copy of a magazine article to the home office, but your fax-modem will only handle items stored on your computer.
With a scanner, the computer world meets the paper world.
Scanners digitize printed images. That means they turn documents into patterns of digital 1s and 0s that your computer can store, edit and transmit.
You can scan a paper invoice and send it to accounts receivable using your fax-modem. You can scan photographs or line art to spice up your presentations, the PTA newsletter or your Web page. If you're befuddled by mounds of paper, you can scan correspondence, reports or even printed forms and convert them into documents you can edit with your word processor or spreadsheet program.
Although expensive scanners have been used by graphics professionals for years, economical scanners with user-friendly software have become popular in the home- and small-office market. Sheet-fed scanners for documents and photo-size scanners for pictures are available for as little as $30. Good flatbed scanners start at about $50. You'll pay more for enhanced color capability, resolution and higher speed.For additional convenience, most manufacturers have produced "combo" units that perform the function of several different peripherals: printing, scanning, copying, and faxing. The price tags on these units are higher, but usually quite reasonable.
Scanners come in a variety of sizes and price ranges, with capabilities to match. But whatever scanner you buy, make sure it's "TWAIN Compatible." That means it meets an industry standard that lets other programs control the scanner directly, rather than forcing you to use special scanning software. Hook up a TWAIN-compatible scanner to your computer, and you may suddenly find that your graphics programs have sprouted an "acquire/import" menu that, after a little configuration, will let you directly scan photos or graphics.
These are the best of the breed... and the most expensive. However, flatbed prices have been dropping rapidly. A flatbed consists of a box with a glass top and a hinged cover; you put your document face down on the glass. Inside the box, a scanning element moves across the length of the page and converts it into digital information. Some color units require three passes of the scanner head to record a photograph, while others can do it in one pass.
Advantages to a flatbed:
Quality. In a flatbed, the image is stationary while the scanner head moves, an arrangement that's inherently more reliable than having the paper move through rollers.
Better color ability. Although some sheet-fed scanners can do color work, you'll need a flatbed for quality work with anything larger than a snapshot. You'll definitely need a flatbed to scan pages from magazines, books or other bound documents, or if you want to try your hand at scanning three-dimensional objects (which is surprisingly effective).
Disadvantages to a flatbed:
It takes up additional space on your desk or work area.
Sheet-fed scanners use rollers to pass a sheet of paper or photograph over a stationary image head. They're best for converting printed documents to faxes or as front-ends for optical character recognition (OCR) software, which converts typewritten documents to computer-editable text files. Most inexpensive sheet-fed scanners are designed for black-and-white work, although most models can handle color.
Advantages of sheet-fed scanners:
They're often faster than color flatbed scanners.
They don't take up much space on your desktop since they are generally integrated into a printer/copier unit.
You can find sheet-fed scanners that plug into your computer's usb port and you can easily move these scanners between computers.
Some sheet-fed scanners can accept more than one page at a time, which makes them quicker at processing a stack of documents.
Disadvantages of sheet-fed scanners:
They generally can't produce the image quality that flatbeds can, largely because they're trying to hit a moving target: a sheet of paper traveling over rollers.
Aligning the paper can be a problem, particularly if your document is smaller than a full page.
You can't scan books or magazines with a sheet-fed scanner.
These relatively inexpensive tools consist of a small scanner element four to five inches wide that you drag over the image. Most come with software that allows you to scan a full page in two sections and "stitch" them together on your screen. Some hand-helds have a clamp-on motor housing that turns them into sheet-fed scanners for use with small images -- mainly photographs and business cards.
Hand-helds are good for scanning logos or other small pieces of artwork. They're not likely to give you the quality of a larger sheet-fed or flatbed scanner because they rely on the steadiness of your hand. But they're inexpensive and great for scanning documents at libraries or other locations away from your desktop.
These little specialized scanners are designed for one purpose: turning your snapshots into digital images. Some manufacturers build them into multimedia computers. You just slip your snapshot into a slot in the front of the computer and watch it pop out when the scan is finished.
If you're interested in turning photos into Web page graphics, illustrating a brochure or catalog, or giving the kids a chance to spice up their party invitations, a photo scanner can be a welcome addition to your PC. But they're generally limited to 5-by-7-inch pictures. If you want to scan text pages or larger photos, get a flatbed or sheet-fed scanner.
Multipurpose office machines combine a scanner, printer, copier, fax machine and modem into one unit selling for $150 and up. They're popular because they're reasonably priced, and they reduce desktop clutter. As scanners, they can operate like sheet-fed units or flatbead units, although you may not get the same resolution or quality you'd expect from a dedicated scanner. If quality scanning is important to you, check out the resolution specifications of these machines carefully before you buy.
Resolution. A scanner converts images into patterns of dots. The smaller and closer together these dots, the better the image quality. The number of dots per linear inch (dpi) a scanner can record is known as its resolution. Typically, scanners can record images at several different resolutions -- the important figure is the maximum resolution.
Inexpensive scanners may have resolutions of only 200 dpi, which means 40,000 dots make up each square inch of the image. The best can record at 600 dpi or more. But be careful, because scanner makers can enhance resolution artificially using software, which is not quite as good as the real thing. If in doubt, check out the scanner's "optical resolution," which is the true measure of the machine's capabilities.
Pixel depth (bit depth). If the world were black-and-white, scanners would only have to be able to record one color -- black. But we live in a world of rainbow hues. So when a scanner turns an image into individual dots, or pixels, it has to be able to record color or grayscale information about each dot. If it can record more information, it can produce a more accurate reproduction of the original.
A scanner's "pixel depth" or "bit depth" tells you how many digital ones and zeros it uses to record color or grayscale information about each pixel. More is usually better: A greater pixel depth represents more grayscale gradations between black and white.
An older, one-bit scanner can record only black and white. An eight-bit scanner can record up to 256 colors or levels of gray. Better color scanners have 'True Color' capability, which means they can discern up to 24 million colors -- about the limit of most people's vision. Expensive 32-bit scanners -- mainly used by professional publishers -- can do even better.
Speed. Speed is important if you're doing a lot of scanning. Some scanners may take a couple of minutes to process a color page -- others may be able to do it in 30 seconds. Some may work faster than others with pages of text. There are no real standards here, and the speed of your computer may be just as important as the scanner's speed in delivering the final image. Check out the manufacturer's claimed speed rating -- but take it with a grain of salt. If in doubt, first try the scanner out on the type of documents you'll be using.
Maximum scan size. This is primarily an issue with flatbed scanners, which are limited by the physical size of the scanning bed. While most scanners can handle 8.5-by-11-inch paper, they may not be able to scan completely from edge to edge and top to bottom. Likewise, if you're scanning legal-size paper, you'll need to find a scanner that can handle the extra length -- not all do. Check out the scanner's maximum scan size.
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