QUESTION: What is a PDF417 symbol?
ANSWER: PDF417 is a
2D (2-D) stacked bar-code symbology that's used in a variety
of applications, primarily transport, identification cards, and
inventory management. Developed by Symbol Technologies, the PDF417
technology allows for creation of a symbol that consists of 3 to 90 rows,
each of which is like a small linear bar code.
PDF417 symbols can store much more data than other 2D symbols.
A PDF417 symbol
2D and 2-D stand for "two-dimensional."
As mentioned above, PDF417 symbols are two-dimensional symbology
(horizontal being one dimension and vertical being the second dimension).
Contrast this with other kinds of bar codes that we see in our daily lives —
most of them are "one-dimensional" bar codes. That is: the marks that
make up the bar code are arranged in one row (one dimension), usually the
A UPC bar code
UPC bar codes are
one-dimensional bar codes.
They are found on product packaging in supermarkets
and other retail environments.
A Code 128 bar code.
Code 128 bar codes are
one-dimensional bar codes.
They are widely used
in many industries, particularly
related to shipping and packaging.
What kind of information can be represented by a PDF417 symbol?
A PDF417 symbol can represent much more data than other kinds of 2D symbols.
A single PDF417 symbol
can carry up to 1.1 kilobytes of machine-readable data; and it can
contain biometric data such as photographs, fingerprints,
and signatures, as well as text, numerics and graphics.
PDF417 symbology is well suited to applications where it is
impractical to reference a database at the time that a
card or document is scanned with a wand or camera. That is —
many details about the thing that the PDF417 symbol represents can
actually be stored right in the PDF417 symbol.
To put it another way:
sometimes bar codes contain a minimal amount of information, and when
the bar codes are read, the bar codes themselves don't contain much data —
instead, each bar code contains a code that is used to look up information
in a database. This is what happens at the supermarket: the checkout clerk
uses a wand to scan the UPC bar code on each item that you buy, and information
about that item is retrieved from a database.
How do you get the information out of a PDF417 symbol?
To understand the information a PDF417 symbol represents, you need a scanning wand or
camera that is programmed to understand and interpret PDF417 symbols.
A PDF417 barcode uses a type of error-correction known as
"Reed Solomon error correction." The Reed Solomon
error correction allows the symbol to withstand some damage
without causing loss of data.
What are PDF417 symbols used for?
Virtually any kind of data can be represented in a PDF417 symbol.
Currently, PDF417 symbols
are being used on drivers' licenses, social-services ID cards,
national ID cards, and many other kinds of documents.
How can you put PDF417 symbols on your documents?
The process of putting PDF417 symbols on your documents isn't as straightforward
as putting one-dimensional bar codes on your documents.
Let's compare the two processes.
In most situations, to put a one-dimensional bar code on a document, you just need to
type the information to be represented (or somehow generate that information automatically),
and you need to format that information with the proper bar-code font.
The procedure for putting a PDF417 symbol on a document is different and
more complicated than what we've just described, for two reasons:
We offer variable-data-printing applications that can produce PDF417 symbols that represent information in a data file.
to learn about them.
- Since a PDF417 symbol is two-dimensional, you can't
represent the information in it with just one line of
characters in your document.
- The relationship between the marks that make up the PDF417 symbol
and the information that those marks represent is more complex
than the relationship between the marks that make up a one-dimensional
bar code and the information that the bar code represents.