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Scanners Demystified   
Intimidated by the world of scanners and scanning technology? Don't be. This article makes bit depth, OCR, and resolution easy concepts to grasp.
@Copyright 2004, TechSoup, a project of CompuMentor

Few computer peripherals have become as popular in the past few years as the desktop scanner. With the vast expansion of the graphics-hungry World Wide Web, and the increasing popularity of desktop publishing, scanning images has become a common task and could be a big hit with your patrons. Fortunately, for budget-conscious libraries, as scanners have become more popular, their prices have decreased dramatically. While the digital camera's increasing affordability will eventually make scanners obsolete, for now they are still valuable library tools. Here are a couple of things you should know before you buy.

TWAIN

Most scanners today are known as "TWAIN compliant." TWAIN is an important industry standard that allows you to use your scanner from within virtually any graphics software application (Adobe Photoshop or Macromedia Fireworks, for example). While rumored to stand for, "Technology Without an Important Name," TWAIN actually stands for nothing at all and playfully refers to the saying. "Ne'er the twain shall meet," or perhaps, "Meeting of the TWAIN," according to the Hewlett Packard Web site. TWAIN may not stand for anything specific, but you shouldn't buy a scanner that doesn't comply with its standard.

OCR

OCR, which stands for Optical Character Recognition, is an extremely useful application of scanner technology. Usually handled by software that comes with the scanner, OCR takes an imaged document and reads the text that is contained within it. For instance, say you receive a letter in the mail that you would like to incorporate into another document. Normally, this would require retyping of the entire letter, but with OCR, you can simply scan the letter, and let the software extract all the text. After that, it is simply a matter of cutting and pasting to put the editable text in your document.

Resolution

A scanner's resolution determines the amount of detail it can handle. Like printers, a scanner's resolution is measured by dots per inch (dpi). The higher the dpi, the better the image quality. Most scanners today have a hardware (optical) resolution of at least 600 dpi or above. Software (interpolated) resolutions can go much higher. This is satisfactory for everyday library use.

Sheetfed vs. Flatbed

Flatbed

Similar to most office copiers, flatbed scanners provide a flat, glass surface on which you can place nearly any object that you want scanned. This simple design lets you close the lid, hit the Scan button, and move on with your life.

Pros:

  • can scan book pages, and most anything that you can fit on top of the glass panel

  • generally better image quality

  • no paper jams

Cons:

  • take up more space

  • glass must be kept clean for good image quality

  • multiple page scanning can be a hassle

Sheetfed

A sheetfed scanner is slightly pickier than a flatbed about what it will scan. Sheets of thin paper are generally the only objects that can fit through the paper feeder to be digitized. While the space this design saves is ideal if your scanning needs are limited to sheets of paper, you are out of luck when confronted with a book or magazine article that needs reproducing.

Pros:

  • compact

  • able to scan multiple pieces of paper easily with a feeder

Cons:

  • can only scan thin sheets of paper (no thick paper or books)

  • resolution tends to be lower than flatbed scanners

Conclusion

For libraries, an inexpensive flatbed scanner is perfectly adequate for OCR and the digitizing of images for presentations, newsletters, and Web publishing. If you are only interested in scanning pieces of paper (for faxing from your PC or a similar application), a sheetfed scanner may save you some room, though flatbed models have gotten a lot smaller over the years. However, if you plan to work with high-end graphics, you may need to invest in more expensive scanning equipment.


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