Code Barre

Code Barre Lineaire:

Il existe une variete importante de standart de code barre.

Code Barre bidimensionel : Datamatrix

Datamatrix (or Data Matrix) is a two-dimensional matrix barcode consisting of black and white square modules arranged in either a square or rectangular pattern. The information to be encoded can be text or raw data. Usual data size is from a few bytes up to 2 kilobytes. The length of the encoded data depends on the symbol dimension is used. Error correction codes are added to increase symbol strength: even if they are partially damaged, they can still be read. A Datamatrix symbol can store upto 2,335 alphanumeric characters.

Universal Product Code (UPC)

The UPC (Universal Product Code) was the original barcode widely used in the United States and Canada for items in stores. The first item to be placed under a UPC scanner in a retail store was a 10-pack of Wrigley's Juicy Fruit chewing gum at Marsh's supermarket in Troy, Ohio, on June 24, 1974.
In the UPC-A barcode, each digit is represented by a seven-bit sequence, encoded by a series of alternating bars and spaces. Guard bars, shown in green, separate the two groups of six digits.The UPC (now officially EAN.UCC-12) encodes twelve digits as

SLLLLLLMRRRRRRE

• where S (start) and E (end) are the bit pattern 101,


• M (middle) is the bit pattern 01010 (called guard bars),


• and each L (left) and R (right) are digits, seven bits long each.

This is a total of 95 bits. The bit pattern for each numeral is designed to be as little like the others as possible, and to have no more than four 1s or 0s in order. Both are for reliability in scanning. [2]

Reference:

[1] http://en.wikipedia.org/wiki/Datamatrix
[2] http://en.wikipedia.org/wiki/Universal_Product_Code
[3]