PDF417: History, Advantages, Limitations, Usage

PDF417 is a 2-d barcode type with high density and data encoding capability. It can encode a large amount of data.

“PDF” means Portable Data File, and “417” signifies the pattern in the code. This stacked linear barcode format has had numerous applications for identification cards and inventory management. This article explores more on PDF417 from its origins to its usage.

1. History
2. Structure
3. Variations
4. Purpose
5. Advantages
6. Limitations
7. Usage

History

PDF 417 was developed in the year 1991 by a researcher named Dr. Ynjiun P. Wang at Symbol Technologies. Recently Symbol Technologies has been bought by Motorola.

Dr. Ynjiun designed it as a system for encoding and decoding data in machine-readable graphic form. This image form would have encoded data and printed on a carrier such as a card or paper document. Then a recognition device converts the image on the transport into electrical signals representing the symbol by scanning the image.

Subsequently, a high-level decoder further decodes the codeword values into data, which can then be output for processing or use. His idea was patented in 1993 and defined in ISO standard 15438.

Structure

PDF417 actually consists of a set of linear codes stacked together to give a 2-d outlook. It is has been named PDF417 because it consists of 4 bars along with white spaces, where each bar is 17 units long. PDF417 is also referred to as Macro PDF, Macro PDF417, or the portable data file.

The PDF417 bar code or symbol consists of 3 to 90 files, each of which is like a small linear barcode. Each row has a start pattern, quiet zones, row indicators, data codewords, and a stop pattern. The functions are as follows:

• The quiet zone is an allotted minimum amount of white space before the bar code begins.
• The start pattern identifies the format as PDF417.
• The “row left” codeword carries information about the row, such as the row number and error correction level.
• Data codewords are a group of bars and spaces about 1-30 representing one or more numbers, letters, or other symbols.
• The “row right” codeword carries more information about the row.

This design made it possible to have up to 929 available code words. Of these, there are 900 mandated for data, and 29 for particular functions, such as shifting between significant modes. The three considerable methods are encoding different types of data in different ways, with the possibility of shuffling as necessary within a single bar code. Namely:

• Byte: each group of 5 codewords represents 6 bytes.
• Numeric: there was a maximum of 44 digits in 15 code words.
• Text: Each codeword represents two base-30 digits, which are used by a system of four submodules to describe the printable characters.

Variations

PDF417 has two main specialized variants namely, Macro PDF417 and Compact PDF417. Macro PDF417 is useful for splitting very large files that need to be encoded in a single symbol into manageable segments. Compact PDF417 is useful to overcome the size limitations to conserve the room despite the restricted space available and also reduces the chances of symbol getting damaged.

Micro PD417 is a different symbology created based on PDF417 and it is useful when space considerations are the main concern. They are very similar however the key difference is that the micro version provides a limited set of symbol sizes. For each given symbol size, there is a fixed level of error correction that is supported. This means that the specified symbols support at least 28% of error correction codewords.

Purpose

The basic purpose of the PDF417 barcode type was to develop an encoding technique that could encode huge and complex data types. Before PDF417, most of the encoding techniques could only encode alphanumeric data along with some special characters, however, there was a need for barcode which could encode large files, images, and complex data, for this purpose PDF417 was developed which suffice the said requirement.

Advantages

• It can encode a large variety of data types such as numeric, alphabets, binary, special characters. It can also store files including photographs, signatures, fingerprints, and several types of graphic formats.
• It can be scanned with handheld scanners as well as linear CCD scanners.
• PDF417 has an extremely high density and can store large amounts of data like other 2-d barcodes.
• Users can specify the length and width of the barcode, unlike standard widths and lengths.
• No license is required to print this barcode format. It has Public Domain Format.
• Large damage tolerance like other 2-d barcodes.
• The built-in error detection mechanism namely Reed-Solomon error correction.

Limitations

• It is often larger in size as compared to other 2-d barcodes like QR code and DataMatrix and takes up to 4 times more space.
• It is extremely sensitive to the angle of the scanner and tilted scanner might not be able to decode correct information.

Usage

Due to its many advantages and superior encoding capabilities, PDF417 has found many applications by both commercial and government organizations. The following are examples of how PDF417 is being used:

• PDF417 barcode type can be used to print postages which are recognized by the United States Postal Department.
• PDF417 is extensively used in the transportation sector, particularly in the automotive industry like QR Code and other 2-d barcodes.
• Used in the airline industry. PDF417 is inscribed on boarding passes.
• PDF417 barcodes are also included on visas and border crossing cards issued by certain countries such as the State of Israel.
• Companies like FedEx use PDF417 barcodes on packing slips and labels to automate delivery and tracking.
• Inscribed on driving licenses and Real ID, issued by The Departments of Homeland Security.

Conclusion

In scenarios where we need to store complex data information in a barcode such as images and high graphic data, PDF417 is the best data format to use.

Bytescout BarCode  SDK and BarCode Reader SDK are able to generate and read PDF417.

   

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