Code Numbers

Barcode Readers

• The bar code is a pattern of thick and thin bars divided by thick and thin spaces. Only the relative separations and thickness of the bars are important.

• Barcodes can be printed in different sizes and colours. The barcode is read either by passing a light-pen over it  or by passing the bar code over a flatbed scanner.

• Barcodes are suitable for data input when all that is necessary is to identify an item, and the data input simply comprises a code.

• systems are easy to operate and have very low error rates.

• Occasionally, a scanner can read a barcode number incorrectly. A check digit is included in the barcode number to reduce such incidents

Graphic Capture

• Image Scanners are popular examples of graphic capture devices. When a page of text already exists, like the page that you are reading now, it can be directly put into a computer using a scanner.
• Scanner can be used to input not only the texts, but also the photographs, drawings and so on. Image Scanners  (Gray-scale or colour) digitise the pictures (which are analog data). The resulting bitmapped images (Each pixel has a collection of bits that define its colour) can be easily modified by graphics programs. The resolution of bitmapped images is measured in dpi, i.e. dots per inch.