PDF417 – one really useful barcode standard
PDF417 is checked, multi-line barcode which is said to be the most widely used 2-D symbology in the world. PDF is equivalent of Portable Data Format. The “4” stands for the number of bars and spaces, which are used to encode every character, and the “17” means that the total width of these eight bars and spaces is 17 units.
There are several key factors that make PDF417 so commonly worked with:
- Very high data capacity;
- Error correction levels;
- Macro PDF417;
- Custom dimensions are available;
Check out Mobilio’s PDF417 generator and download it now from the Mac AppStore.
To start with the impressive data capacity of PDF417. It can encrypt all the 128 ASCII characters and 8-bit binary data. Practically there are three encoding schemes – byte, text and numeric. The amount of information a single PDF417 can carry is astonishing for a barcode – over 1100 bytes, 1800 text characters or 2710 numerical digits. The set of 929 codewords (900 for data and 29 special symbols) make the Portable Data Format extremely useful and efficient. Due to the large quantity of symbols that can be encoded, PDF417 serves not only for identification like the normal 1-D codes, but as source of essential content too. Product’s specification or information connected with manipulation or shipment processes can be stored. As a result the user will be much more eased because he won’t have to connect to any additional database, he will get what he need with the scanning. PDF417 is now adopted in many spheres of our everyday life – in industry, by national organizations, for postal and airline services. The adequate and secure encrypting technique allows fingerprints or electronic signatures to be represented as machinery-readable data. Actually there is such tendency in the USA for providing important characteristics of the driver. Instead of writing down extensive ID numbers they just scan the driving license and everything is collected.
Example of damaged PDF417 barcodes
As most of the others 2-D barcodes, one of the fundamental traits of PDF417 is error correction. For those who haven’t read my previous articles, error correction basically gives your barcode the ability to lose part of its codewords, but still to be readable and to provide all the encoded characters. It is really handy for users whose barcodes are probable to be damaged or be kept under harsh conditions. PDF417 has 9 levels of error correction: from 0 to 8 where the number of the restored codewords are degrees of 2. At level 0 they are 2 (2^1), at 1 – 4 (2^2), ….. , at 8 – 512 (2^9). In essence if your PDF has 100 damaged codewords and it also has level 6 of error correction all of them will be restored during the scanning.
So far so good. Exceptional data capability of over 1.1 Kb, efficient error correction, but there’s even more. PDF417 standard presents one more convenient feature and it is called Macro PDF417. In the previous paragraphs I said that PDF is used in the industry for instant database – it provides foremost information on the second of scanning. Sounds pretty useful but with one little disadvantage – this foremost information might be longer than the 1800 allowed text characters. That is why Macro PDF417 was invented. If your string is made of 3000 symbols you will simply encode it into two barcodes and will put them one after another. After reading them consequently the scanner will still be supplied with the necessary data.
PDF417 is 2-D barcode which means that it is composed of rows and columns. As I already mentioned there are 929 codewords available in the Portable Data Format. Each symbol is encoded with a codeword. A single codeword is a combination of 4 bars and 4 spaces with variable dimensions (like in the picture on the left). There is one main rule – the total width of the 8 elements to be 17 units. What is user-friendly here is the fact that you can adjust the width and the height of these units and you can also customize the number of rows and columns. Here is a list of all other Mobilio’s barcode producers.
In conclusion I would say that PDF417 is really a smart invention because of it great features. With its developing, new possibilities rose on the horizon for barcodes. They started to appear not only on product packages, cartons or boxes, but on driving licenses, boarding passes and are used as electronic signatures. All in all if barcodes are becoming so deeply integrated in our everyday lives, it is good to be well-informed about them, don’t you think?