The 2D-Superscript is a variable-size, variable-density two-dimensional symbology offering very high user data capacity at a guaranteed minimum level of error-correction. 2D-Superscript2DSuperscript is specifically designed to support low-cost printing devices such as laser printers, inkjet printers and plastic card printers.

Each 2D-Superscript symbol is composed of a rectangular array of binary-encoded rectangular modules bounded on all four sides by a framing pattern. A 2D-Superscript can be created with a wide variety of aspect ratios, including square and near-square aspect ratios, but a typical 2D-Superscript symbol has a high aspect ratio. 2D-Superscript symbols are commonly referred to as “2D-Superscript”. A high-aspect ratio 2D-Superscript symbol can be positioned in either a “tall” or “wide” orientation without significant impact to the decoding process.

An enlarged sample of a 2D-Superscript is shown in Figure 1. This particular 2D-Superscript (when printed at “normal” size) employs 0.010” x 0.010” features, is approximately 3” x 0.88” in overall size, encodes at least 1924 user data bytes (assuming no data compression) and has at least 12.5% correctability (erasures).

In anticipation of emerging applications such as secure ID cards, medical data cards and machine readable travel documents, a 2D-Superscript encodes user data into one or more data fields. Each data field encodes a specific type of data. Up to 254 fields can be encoded into a single 2D-Superscript. Supported field types include text, binary and image (i.e., photograph) fields at this time.

The capacity of a 2D-Superscript depends on the size of the symbol and the size of the printed modules (bits) that make up the symbol. In a typical 2D-Superscript employing 0.00667” x 0.010” features (2x3 printer pixels per module at 300 dpi), the raw data encoding density approaches 1875 bytes per square inch within the data field, less the space required to encode the embedded data header blocks (about 2.5% overhead on a typical 2D-Superscript). Framing overhead further reduces overall density. In a 2D-Superscript measuring about 0.62 inches by 3 inches and encoded with rectangular bits of this size, however, the “raw” data capacity is 2920 bytes for an effective raw data encoding density of 1587 bytes per square inch (accounting for framing overhead only). After accounting for the embedded data header and minimum error correction overhead, the user data capacity of the 2D-Superscript is not less than 2100 bytes. With all overhead sources accounted for (i.e., framing, data header, and error correction), the effective user data encoding density of such a 2D-Superscript is not less than 1141 bytes per square inch.

Figure 1: Sample 2D-Superscript

Once encoded in the above format, 2D-Superscripted image is referred to as 2-D Superscript.

Information Flow and Architecture

The main forms of information flow are as follows:

• Encoding information into a 2-D Superscript
• Printing 2-D Superscript on a document / paper
• Scanning 2-D Superscript from a document / paper
• Decoding information from a 2-D Superscript

As was mentioned earlier, 2-D Superscripts provide a means by which to store text, binary, compressed image data, and biometric information into a compact, printed form which can later be machine read (i.e. scanned and decoded) and reconstructed back into the original text, binary, compressed image, and biometric information. As these items are added to the 2-D Superscript, the information is compressed, optionally encrypted, and then printed with embedded error correction logic so that even if the 2-D Superscript suffers some forms of destruction it will still be able to be decoded and reconstructed.

2-D Superscripts manage these varying data types by placing each different piece of information into it’s own characteristic field type. More than one of the same field type can exist in a 2-D Superscript, which permits multiple pictures, multiple text fields, and multiple binary entries to be handled easily.

The input field management, compressing, and encoding of the 2-D Superscript is accomplished through the encoding process. The finding, decoding, decompressing, and output field management is handled via the decoding process.

The very same information that is encoded into a 2-D Superscript can be “re-directed” and printed to documents that carry legal implications.

2D Barcode Specifications

2DSuperscript is a high-density two-dimensional bar code that allows users to store vast amounts of information in a compact machinereadable code. 2DSuperscript can encode more data than other bar code symbologies, in one-third the amount of space, with no sacrifice in error correction. For example, an area of 3.2” x 0.7” can store up to 4,425 bytes of data, ideal for bar code storage of photographs (both colour and grayscale), multiple biometrics and text. 2D bar codes are typically used for applications such as Passports, National ID Cards, Driver’s Licenses, Voter Registration Cards, Access Control Cards, Health Cards, Financial Cards, Bills of Lading, Birth Certificates and other Documents. The International Civil Aviation Organization (ICAO) has accepted Datastrip’s symbology as an acceptable technology for use on Machine Readable Travel Documents (Passports & Visas). Datastrip offers a 2DSuperscript Software Developer’s Kit (SDK) for system integrators and developers, who want to add the power of high-density, secure 2D bar codes to their own programs.

Symbology Specifications

Maximum Bar Code Size: * 1.20 inches x 7.00 inches
Maximum Capacity: * 9,615 user bytes with 25% error correction
Minimum Bar Code Size* 0.37 inches x 0.56 inches
Minimum Capacity: * 90 bytes
Bar Code Area Damage: Datastrip 2D symbologies incorporate a minimum error value of 6.5% random area change and up to 11.5% block area damage
Error Correction: Reed Solomon, user adjustable from minimum of 25% - 50%.
Rotational Tolerance: Can be read in any orientation using Datastrip algorithms
Field Types: Biometric, Photograph, Text
Photographic Compression: Grayscale, JPEG and Summus high performance color wavelet. New compression algorithms can be supported as software plug- ins
Bar Code Output Formats: BMP, DIB
Printing Densities: 300 dpi and higher recommended
Printed Media: All standard laminated and non-laminated ID cards, passports and other paper documents
Inkspread Compensation: Yes

Note: * Calculated with a feature size of 0.0067 inches x 0.01 inches.

User selectable feature: sizes range from 0.005 inches to 0.020 inches.

2DBarcode Features

• 2DSuperscript is high density: up to 4,425 bytes of information in an area 3.2” x 0.7”.
• 2DSuperscript is secure: Cannot be fraudulently produced or altered once printed.
• 2DSuperscript is durable: Features Reed Solomon error correction to tolerate wear and tear.
• 2DSuperscript is cost effective: Adds no cost to the card or document production system.
• 2DSuperscript is flexible: Can easily be integrated into a variety of identity document production systems.
  

2D Barcode Applications

Major areas where 2D Symbology is being successfully used include: