A scanner is similar to a photocopier, except that instead of producing a paper copy of the document you place on it, you get an electronic copy which appears on your computer screen. A scanner works by digitising an image. The images are represented as bitmaps. The bit map images can be stored in a file, displayed on a monitor or manipulated by programs.
Flat bed scanners are used to scan both text and images. They are wide enough to allow scanning of books as well. High end book scanners are available wich are being used by libraries to scan large volume books. Auto feed scanners can scan only loose sheet of papers only. Bar code scanners are small hand held devices that are used read the bar codes. The bar code is a pattern of thick and thin bars divided by thin spaces. Each bar code represents a number which could be a price of the product orISBN number of a book. Retail shops use printed bar codes on their merchandise to track inventory and sale.
Print documents can be easily fed in to the computer without retyping (rekeying) with the help of Optical Character Recognition (OCR) technology. OCR devices facilitate direct manipulation of printed documents. A simple variation of OCR is Optical Mark Recognition (OMR) which electronically extracts intended data from marked fields such as check boxes or and fill-in fields on printed forms.
Magnetic Ink Character Recognition (MICR)systems are used to read characters which are printed in magnetic ink. This technology is widely used by banks to process cheques. Numbers and characters printed in the bottom of the cheque are printed using magnetic ink.
Magnetic strips are small length magnetic tapes which may be stuck to a tag, card or documents. The back of a credit card for example has a magnetic strip that contains magnetically encoded numbers. Credit card reader can reader can read these encoded numbers and transmit them on a computer for verification.