Two-dimensional barcodes (2D barcodes)

In two-dimensional barcodes, a value is encoded in a two-dimensional plane with the use of black and white pixels. 2D barcodes usually have a significantly greater information capacity than linear barcodes, but their higher complexity also means that, in some cases, they are considerably more prone to image errors. This, in turn, means that they need an error correction method. Both the height and width of 2D barcodes are subject to strict rules, as every pixel on the code can potentially contain important information. Accordingly, these formats very frequently involve requirements concerning the available heights and widths, width-to-height ratios, and the geometric shape of the barcode in general.

Data Matrix

Character set: ASCII (1-255)	Capacity: Variable	Encoded value: webPDF
The contents in a Data Matrix code are encoded in the data region by using filled and empty cells. Depending on the selected type, these barcodes will have either a rectangular or square basic shape. Data Matrix barcodes feature a solid line at the left and bottom margins and segmented lines at the top and right margins – on one hand, this makes it possible to locate the barcode; on the other hand, it makes it possible to determine whether the barcode has been rotated. Data Matrix barcodes feature an integrated error correction mechanism based on the Reed-Solomon algorithm. This mechanism ensures that parts of the matrix can be recovered even if the code has been heavily damaged.

caution

When using the web service to recognize Data Matrix barcodes, it is absolutely necessary to make sure that the image area being scanned is limited to the Data Matrix barcode so that the barcode will be as centred within the area as possible. It is important to avoid sources of error such as text and other images as much as possible. In addition, Data Matrix barcodes require a "quiet zone" (a frame) around them without fail. The width of this quiet zone must be at least equal to the length of an encoding symbol’s side.Example: If a Data Matrix cell is 2 pixels by 2 pixels, the quiet zone must have a width of at least 2 pixels.

QR code

Character set: ASCII (1-255)	Capacity: Variable	Encoded value: webPDF
In Quick Response Codes, information is encoded in a manner similar to that used for Data Matrix codes, with filled and empty squares being used in a basic square shape. QR codes are optimized in such a way that they can be automatically recognized and read as quickly as possible. In fact, they are a very popular way to store information (such as a web address) in a format that can be easily recognized and read by cell phones (mobile tagging). Normally, QR codes feature three position markers that make it easier for scanners to recognize the barcode and its orientation. The maximum conceivable information content for a QR code is 2,956 kB, but the actual capacity will also depend on the selected error correction level. This error correction level indicates the percentage of encoded data that it will be possible to restore with the Reed-Solomon algorithm (Low: 7%; Medium: 15%; Quartile: 25%; High: 30%). The higher the recovery percentage, the lower the remaining barcode capacity – however, higher levels also ensure that the barcode can sustain a greater amount of damage before becoming unreadable.

Aztec

Character set: ASCII (0-127), extended ASCII	Capacity: Variable	Encoded value: webPDF
In Aztec Codes, information is encoded with the use of empty and filled squares arranged concentrically around a square core. This core not only makes it possible to recognize the barcode, but also indicates its orientation. The resulting structure is reminiscent of stepped pyramids, which is where the format gets its name from. Each layer around the core is made up of two rings of encoding symbols, and the fact that each additional layer has longer sides means that it can represent more data. Layers are added outwards starting from the centre, meaning that the longer the encoded message, the more space an Aztec Code will need. Aztec barcodes feature an integrated error correction mechanism that is based on the Reed-Solomon algorithm and that can be configured to occupy any percentage of the barcode’s symbol capacity. This mechanism ensures that parts of the matrix can be recovered even if the code has been heavily damaged. To date, Aztec Codes have been used primarily to label pharmaceutical products, as well as for tickets for public transportation.

caution

When using the web service to recognize Aztec barcodes, it is absolutely necessary to make sure that the image area being scanned is limited to the Aztec barcode so that the barcode will be as centred within the area as possible.

PDF417

Character set: ASCII	Capacity: Variable	Encoded value: webPDF
The "Portable Data File 417" barcode format is used first and foremost to encode relatively large amounts of data. Each code pattern consists of 4 bars and 4 empty spaces and has a length of 17 encoding units, which is where the 417 number comes from. PDF417 barcodes can consist of 3 to 90 rows, with each individual row essentially representing a linear barcode that also contains information regarding its content, row number, etc. The fact that the individual rows are independent from each other means that PDF417 barcodes can be read by most linear scanners as well,. This sets this type of barcode apart from all other 2D barcodes, which require more complex image recognition. PDF417 barcodes feature an inner 8-level Reed-Solomon error correction algorithm, and the higher the level, the more resistant a barcode will be to damage. In addition, PDF 417 barcodes have the option of qualifying encoded content – a specific number of codewords is required for an individual codeword depending on the selection –, making it possible to make these barcodes more compact:Text - each codeword represents two letters.Byte - each 5 codewords represent 6 bytes.Numeric - up to 15 codewords represent numbers with a length of up to 44 digits.

Swiss QR invoice

Character set: ASCII(1-255)	Capacity: Variable	Encoded value:
The "QR Invoice" is a standard of the Swiss financial industry and replaces the "payment slips" commonly used there until 30.09.2022.The QR invoice combines a machine-readable QR code with human-readable invoice information and a receipt. The coded content of the QR code is almost identical to the invoice information. A QR invoice can also be recognized by the characteristic Swiss cross in the center of the barcode.The function, capacity and technical implementation of the barcode is otherwise exactly congruent with that of other QR codes and processes that would be suitable for reading a QR code can also be used for QR invoices.