Optical Input Devices

1.    Barcode Scanner/Reader

These devices read bar codes, which are patterns of printed bars that appear on product packages. The bar codes identify the product. The bar code reader emits a beam of light—frequently a laser beam—that is reflected by the bar code image. A light-sensitive detector identifies the bar code image by recognizing special bars at both ends of the image. These special bars are different, so the reader can tell whether the bar code has been read right-side up or upside down. After the detector has identified the bar code, it converts the individual bar patterns into numeric digits—code the computer can understand). The reader then feeds the data into the computer, as though the number had been typed on a keyboard.

2.    Scanner or Image Scanner

A device that ‘scans’ images, book pages, etc. Scanning is basically taking a close-up photograph (just very slowly and with great detail). The scanned image data is passed to the computer.
The most common type of Image scanner is the flat-bed scanner which has a glass plate on which the item to be scanned is placed. The item is illuminated and an image of it is captured by a moving scan ‘head’.

3.    Optical character recognition (OCR) Device

It is mostly used by banks to convert the scanned image of a typed or printed page into text that can be edited on the computer.