Scanner

A scanner is an input device that takes in an optical image and digitizes it into an electronic image that is represented by digital data.

Description
A scanner can be used to create a computerized reproduction of a printed photo or illustration. It can also be used with optical character recognition (OCR) software to process printed documents into electronic text without having to manually type them in through a keyboard. A 's horizontal resolution, typically measured in dots per inch (dpi), is determined by the number of sensors in the CCD array that scans the document, row-by-row. The vertical resolution is determined by the precision of the, which can be higher than the resolution of the CCD. Some scanners offer interpolation, which can attain a target resolution higher that what the scanner hardware is capable of by computing the pixels in between adjacent pixels.

History
led development of early flatbed scanner hardware in the 1970s for the purpose of optical character recognition for the visually impaired. The resulting device, the Kurzweil Reading Machine, was a large tabletop device that was introduced in 1976 with the ability to scan an inch-high strip of text at a time with 64 kilobytes of memory.

In 1984, Apple Computer engineer Andy Hertzfeld developed the software for ThunderScan, the first scanner for Macintosh, which used an ImageWriter as a sheet-feeding device. Apple introduced its own Apple Scanner in August 1988, leading to a succession of flatbed scanners. However, co-founder Steve Jobs discontinued the costly product line in early 1998 after rejoining Apple to return the company to profitability. Stand-alone consumer scanners have since been largely supplanted by all-in-one multifunction devices that incorporate a printer, allowing them to function as home office photocopiers.

Articles

 * Scanning the Scene with a Flatbed Scanner by Jason Walsh at Low End Mac (2004-08-18)