Matrix code

As a 2D code or 2D barcode optoelectronically readable fonts are referred to, which consist of different broad strokes or dots and gaps between them with the highest possible contrast. In contrast to the one-dimensional bar codes (English barcode) are coded, the data not only in one direction ( one-dimensional), but in the form of a surface with two dimensions, of which the name is derived. The advantage is a higher density of useful information that can be accommodated per unit area. The term code is not available for a type of encryption, but for pictures of data symbols in this context.

The data in the 2D barcode is read by machine by optical readers, such as scanners, camera and processed electronically. Common applications of 2D codes are including in the field of logistics for product labeling and mobile tagging. Due to the higher recording density, they are used for optical data storage. For example, digital audio signals are stored in the optical sound between the sprocket holes of the film in the form of 2D codes.

  • 5.1 Composite codes
  • 5.2 RM4SCC

Classification

The simplest form of 2D bar codes represent the stacked linear bar codes (English Stacked barcode) that are arranged in several rows. Examples of stacked bar codes are PDF417 and Codablock. With the post code RM4SCC is no real 2D code, however, additional information is encoded in the second dimension on the line length.

Array codes received information in the form of a rectangular array arranged as the QR code, Data Matrix or Aztec code. Point codes use individual points for information coding.

There are also 2D codes, which arrange the information in circular rings, such as the shot code. The transition to higher-dimensional bar codes with three or more dimensions for example, via the colors used, as at the High Capacity Color Barcode ( HCCB ) is the case.

Stacked codes

Codablock

Codablock was developed by Heinrich Oehlmann as stacked variation to the standard bar code Code128 Code39 and between 1990 and 1994 in Germany. Codablock can be compared with a line break a text editor most vividly. Once a line is full, the next will wrap each line the line number and the finished block is inserted the number of rows. At the end of a checksum.

Code 49

The Code 49 is a barcode with three error correction method and therefore meets high safety requirements in relation to other marking methods. Code 49 is the first multi-row code, and was developed in 1987 for logistic applications in space by David Allais at Intermec (USA).

PDF417

PDF417 stands for " Portable Data File ". In contrast to other stacked bar codes such as Codablock, Code 16k or Code49 he does not require complete Zeilenkongruenz. Up to 2000 characters can be stored in a PDF417. The PDF417 is not a real matrix code as the data matrix code. There are adjustable error correction levels ( 0-9). In terms of data content relative to the size of PDF417 cuts compared to the data matrix from very bad. It makes sense ( though not particularly efficient) is the use in the context of laser scanners, which can detect no Matrixsymbologien. Once camera systems are used as a scanner, real matrix codes are the method of choice. The PDF417 was originally developed by Symbol Technologies. Meanwhile, the PDF417 is also specified in an ISO / IEC standard.

Matrix codes

Matrix codes could previously only be read with a CCD camera scanners. The orientation of the CCD image plays virtually no role, so that the reading is omnidirectional possible. Meanwhile, some scanner manufacturers laser scanners have evolved to carry out an automatic x / y scan and create an image from the data obtained. Thus, matrix codes can also capture with laser scanners. These have somewhat better optical properties than cameras.

QR Code

QR Code stands for Quick Response code, a very common two-dimensional code in Japan. Many mobile phones with built-in camera can read the code. The QR Code was developed in 1994 by Denso (Japan). It is square and easy to recognize by its finding aids, nested light and dark squares in three corners. The symbol elements are squares, of which at least 21 × 21 and a maximum of 177 × 177 elements are in the symbol. There are four error correction levels that allow for reconstruction in case of damage of 7% (level L ) to 30 % ( step H). It can be each code more than 4000 alphanumeric characters coded. Larger content can be split to up to 16 individual codes. The Micro QR code takes up to 35 digits.

Standard: ISO / IEC 18004

Data Matrix

In the Data Matrix code, the Reed -Solomon error correction adds redundant data. Are therefore codewords for the error correction between 30% and 60% of the code words. Thus some faulty modules can be adjusted without compromising decoding. The code is defined in the international standard ISO / IEC 16022. This 2D code type currently gaining lot of importance. Examples are the electronic stamp ( Internet brand ), parts markings in air and space industry and in medical technology.

If the data matrix code is used with the error correction method ECC200 and together with the GS1 data structure, then it is called the result of GS1 DataMatrix. ( The EAN organizations have all renamed GS1, that was from the CCG in Cologne GS1 Germany. )

  • Standard: ISO / IEC 16022
  • GS1 data structure: ISO / IEC 15418 with reference to the ANSI MH10.8.2

MaxiCode

The Maxi Code was developed in 1989 by UPS for fast identification, tracking and sorting of packages. It contains the UPS tracking number, the weight, the service type of the program and the address information. The concentric circles in the middle ( so-called Bull's Eye) to help scanners to find the barcode. The individual points have a hexagonal shape, in contrast to other 2D codes.

Aztec Code

The Aztec Code is a standalone 2D code type. He is enshrined in the ISO / IEC 24778. In the literature mentioned below Volume 2 of the Aztec Code is also described. The German railway, the Austrian Federal Railways and the Swiss Federal Railways use this 2D barcode on their online tickets or mobile tickets (MMS ) of the DB. Furthermore, the U.S. government used this code to store the biometric data at the entry and exit ( US-VISIT ) program.

Point codes

Point Codes, English dot code, are two-dimensional optical codes with high information density and good reading reliability. The main field of application is the identification of a variety of materials with specific printing techniques, in particular embossing and engraving techniques. Furthermore, the code can even be created with drilling techniques. Applications: for example, in the labeling of the axes on the front side. The code is not the same as the open data matrix code in accordance with ISO / IEC 16022 and DIN V 66,401th

Examples of real dot codes are the Dot Code A or the Snowflake Code, or BeeTagg. The data matrix code in accordance with ISO / IEC 16022 is not a dot code. However, there are applications and labeling processes which operate in so-called DPM ( Direct Part Marking ) - method (eg dot peening ) also with data matrix code. The individual modules of the dot code, based on the data matrix are not square but round and connected and separated. In industrial applications for part identification, this is now a common application that displaces the real dot codes or impossible to only come into play.

Characteristics: compact code, flexibility in the customization of information on a given surface; he is omnidirectional readable.

Special shapes

Composite codes

Composite codes, also called dual code symbols are composed of a linear bar code (1D ) and a 2D code, which is located directly above it.

RM4SCC

The English Royal Mail 4 State Customer Code RM4SCC is an alphanumeric code ( uppercase only ) from the UK, but is now also in other countries ( Switzerland, Austria, Denmark, Australia ) was used. The Universal Postal Union has also issued corresponding specifications.

The RM4SCC in itself is a 1D bar code, but uses the second dimension in the form of differently long strokes to encode to image distortions that are given by the very high print speeds in mail sorting facilities for direct printing to tolerate over larger areas than other barcodes.

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