The PDF417 Barcode: A Closer Look
While many of us may see the PDF 417 barcode on the back of our licenses, or on certain packages, such as FedEx, what is the PDF417 really all about? Basically, the PDF417 barcode allows users to securely and inexpensively store large amounts of text and data; it is the most commonly used 2D barcode. The barcode consists of many linear rows of stacked codewords, with each codeword representing 1 out of 929 possible values from one of any three different clusters. Within each cluster, a different cluster is chosen for each new row, repeating every third row. Since codewords within each cluster are unique, the barcode scanner is able to easily determine which line each cluster originated from.
Typically, PDF 417 barcodes are printed at an X to Y ratio of 1:2 to 1:5, with 1:3 being used most frequently. Lowering the ratio saves a lot of space, but not all scanners can read X to Y ratios of less than 1:3. In addition to X and Y rations, row and column limitations also exist in the PDF417 symbology. While the number of rows and columns can be selected, the PDF417 barcode can only have 30 columns and 90 rows, having only the number of data columns in the symbol selected.
The PDF417 Barcode also allows ASCII functions to be encoded for various operations, such as denoting tabs and returns.
Learn more about the PDF417 barcode and other symbologies here.