PDF417

PDF417 is a two-dimensional barcode symbology designed to encode large amounts of data in a compact, machine-readable form. It is a stacked, grid-like barcode consisting of multiple rows; each row contains patterns of bars and spaces that encode codewords. The symbol includes start and stop patterns and row indicators to aid robust decoding from different angles and orientations.

PDF417 uses codewords and supports several data compaction modes to optimize encoding: Text, Byte, and Numeric. It also includes a Macro PDF mode for very large data sets, allowing multiple symbols to be linked together. The data region is complemented by error correction codewords, which improve readability when parts of the symbol are damaged or obscured.

Error correction is provided by Reed-Solomon ECC; the number of ECC codewords is selectable to balance data capacity with resilience. The total symbol size and capacity depend on the chosen symbol size and ECC level, enabling a flexible trade-off between density and reliability.

Common applications include travel and identification documents, shipping and inventory labeling, receipts, and packaging labels. PDF417 is supported by many barcode scanners and mobile devices, making it a versatile option for logistics, government, and manufacturing settings.

Advantages include relatively high data capacity for a 2D barcode and strong error resilience. Limitations include larger physical size than some alternatives, more complex symbol geometry, and varying levels of consumer device support for scanning.