Barcodes

The Bar Code

Now days, we can see a bunch of black and white lines on any product in a super market. This bunch of lines is called Bar Code. The Bar code contains a unique identification no. of the product. Many of us seen these tiny code and also know how much it is useful for supermarkets, courier services and other stores.

Here we will have a look on the technology, history and future aspects.

History

The basic concept of the bard code is come to make the food stores self served. To make

it possible there should be a universal coding system required. A US based company Logican developed the coding system for grocery stores, called Universal Product Code.

What is a Bar Code?

Bar code is pattern of black lines and spaces between it with varying width

of lines and spaces. These lines represent digits, letters and other punctuation marks, which is in its identification code number. The bar code is actually a machine readable form of the code number of the particular product or item. There are various standards are d

Symbologies

                        The mapping between messages and barcodes is called a symbology. The specification of a symbology includes the encoding of single digits/characters of the message as well as the start and stop markers into bars and space.

There are mainly two types of symbologies:

Continuous vs. discrete

• In discrete symbology, it is composed of n bars and n − 1 spaces. There is an additional space between characters, but it does not contain any information, and may have any width so there is no confusion with the end of the code.

• In continuous symbology, it is composed of n bars and n spaces, with one character ending with a space and the next beginning with a bar, or vice versa. A special end pattern that has bars on both ends is required to end the code.

Two-width vs. many-width

In Two-width symbology bars and spaces of two different widths, "wide" and "narrow". The width of wide bars & spaces are varies between 2 and 3 times the width of the narrow bars & spaces.

In many width symbologies all multiples of a basic width called the module; most such codes use four widths of 1, 2, 3 and 4 modules.

Types of Barcodes