2D Barcode Standards

2D (Two dimensional) Bar code symbols have more data capacity compared to linear bar code symbols. Two-dimensional symbols are categorized in two classes: multi-row (or stacked) and matrix. A 2D bar code is treated as an image. The picture is scanned by a camera which is then decoded.

·           ISO/IEC 15424 Bar code symbology specification – PDF417

PDF417 is a 2-dimensional stacked bar code created by Symbol Technologies in 1991. It is one of the most popular 2D codes because of its ability to be read with line CCD scanners, laser scanners or two-dimensional scanners.

PDF stands for Portable Data File and 417 signifies that each symbol character is 17 modules wide of 4 bars and 4 spaces that make up each code. Each symbol character represents a value ranging from 0 to 928 which is called “codewords” in the specification.

Each symbol also has start and stop bar groups that allow the code to be easily identified. PDF417 is capable of encoding more than 1100 bytes, 1800 text characters or 2710 digits. It allows the full ASCII 128 character set (including extended set) to be encoded. Symbol size is 3 to 90 rows, 90 to 583X in width. It supports bidirectional scanning.

 

·           ISO/IEC 18004 Bar code symbology QR Code

QR Code (Quick Response Code) is a matrix code developed by Nippondenso ID Systems. QR Code symbols are square in shape. Maximum symbol size is 177 modules square, capable of encoding 7366 numeric characters, or 4464 alpha numeric characters. QR Code is designed for rapid reading using CCD array cameras and image processing technology.

 

·            ISO/IEC 16023 Bar code symbology specification – Maxicode

Maxicode (originally called UPSCode, sometimes called Code 6) is a matrix code developed by United Parcel Service in 1992. MaxiCode is made up of a 1-inch by 1-inch array of 866 interlocking hexagons, instead of squares. This allows the code to be at least 15 percent denser than a square dot code, but requires higher resolution printers to print the symbol. Approximately 100 ASCII characters can be held in the 1-inch square symbol. The symbol can still be read even when up to 25 percent of the symbol has been destroyed and can be read by CCD camera or scanner.

There are more than 400 different types of such barcodes. UPC or EAN is the barcode used on most of the retail products.

Depending upon the spacing of the black an white bars, the barcodes are classified as High, Medium and Low Resolution barcodes.

1. High Resolution : Spacing < 0.23mm

2. Medium Resolution : 0.23mm < Spacing <0.50mm

3. Low Resolution : Spacing > 0.50mm