Sheet-fed scanners These use rollers to move an image past the light source
and CCD array. Some sheet-feeders can automatically feed one page after
another, making it possible to scan multiple images in a single event. Commonly
used for OCR (optical character recognition) on scanned printed documents,
they do not work well for scanning books, magazines, or rigid objects. Sheet-fed,
or as they are also called, sheet-feed scanners work well only with loose-leaf
cut-sheet paper documents.
Flatbed scanners The most popular type of scanner because of its flexibility
and ease of use. The material to be scanned is placed on a flat glass surface, and
the light source and CCD array pass underneath it. Because the dimensions of
flatbed scanner area can vary significantly, the scanner should be chosen with
some consideration of the size of the material it is likely to be scanning. Flatbed
scanners are typically the best value for home or small office scanning purposes.Image Software
Like a digitized sound, a visual image must be sent to software before it can be manipu-
lated and stored. Scanners come bundled with software for controlling the scanning pro-
cess and typically include some basic tools for image editing. Advanced tools for image
editing are available from a number of publishers, including: Adobe http://www.adobe.com
Corel http://www.corel.com
Jasc http://www.jasc.com
Ulead http://www.ulead.com
Xara http://www.xara.comVideo Capture Devices
The term “video capture” can be misleading since it suggests that what is captured is al-
ways a moving image. Many video capture devices do capture full-motion video, but
many others, like the popular Snappy from Play Inc., only capture still images, just like
a scanner. Video capture devices, then, are devices that use video cameras or VCRs as a
source for still or moving images. In addition to whether or not moving images can be
captured, video capture devices can also be categorized according to how they attach to
the PC (internally or externally), whether they accept a digital signal, and the type of
compression used.Internal vs. External
Video capture devices typically connect to the PC in one of three ways: An adapter card (usually PCI)(^564) PC Hardware: A Beginner’s Guide