Scanning the Aisles for Reproduction Value
Scanners perform two basic functions with a PC. They can scan--or take a picture of--an image and save it in your computer as a graphics file, which can then be edited and printed. When used with optical character recognition, or OCR, software, scanners can copy pages of text and save them so they can be revised just like any other word-processing document.
Scanners come in three basic forms. For simple page copies or scans, a sheet-fed scanner works best. The sheet-fed scanner is the cheapest of the three. It feeds one page at a time and cannot scan book or magazine pages. To scan book and magazine pages, you need a flat-bed scanner. The flat-bed unit scans images placed on a flat glass surface, much like an office copier. The third scanning device is a hybrid of both a scanner and a printer.
Having decided which scanner best suits your needs, you’ll need to choose how the scanner attaches to your computer. The most common method is a connection through your computer’s printer port. The printer port uses a technology called “pass through” to attach your printer to the scanner so that both printer and scanner work with one physical connection. The downside here is slow scanning. Plus, several printers have problems working correctly with pass-through connections.
Another connection uses a separate board that must be installed in your computer. This board is called a Small Computer System Interface, or SCSI, controller. The upshot here is high speed, but a SCSI controller adds expense to the project and can be tricky to install.
Perhaps the easiest scanner-to-computer connection is via a Universal Serial Bus, or USB, port. Most computers built since late 1997 have at least one--and often two--USB ports. For PC users, USB connections work best with Windows 98 and 98 Second Edition. The nice thing about USB connections is that after you install the software you can connect the scanner to your PC while the PC is running. Your printer still has exclusive use of the printer port.
The quality of the images a scanner can produce is measured by its resolution. A scanner’s resolution is usually described in dots per inch, or DPI. The DPI rating can be confusing because computer monitor screens and printers are also rated in terms of dots per inch. Scanner resolution measures the maximum number of dots that can be sent to the computer at one time. Any scanner that claims a resolution greater than 300 DPI must use software to interpolate the scan, so the quality of your scanned image might depend on the quality of your scanner software.
The secret to good scanning is to select the proper resolution. Don’t assume that you should scan everything at the same resolution. In general, with a 300 to 360 DPI printer, use a scanner resolution of 50 to 100 DPI. With a 600 to 720 DPI printer, use a scanner resolution of 100 to 150 DPI. When you scan black-and-white images or use OCR software, use full scanner resolution.
Expect to pay $75 to $150 for a good flatbed unit. Both Epson and Hewlett-Packard make affordable home scanners that cost less than $300 and produce professional-quality results.
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Jeff Levy hosts the “On Computers” radio talk show from 9 a.m. to noon Sundays on KFI-AM (640).
