QR
CODES
QR code is a type of
barcode which can be read by devices such as smart phones. It was invented by
Toyota’s subsidiary Denso Wave in 1994 to track vehicles during the
manufacturing process. Its design was made such that it allowed high speed scanning
of components. Being internationally standardized under ISO 18004, they can
store up to 4296 characters. The Denso Waves holds the patent rights but the
use of QR codes is license free.
QR codes are two
dimensional, that is, information can be stored in both horizontal as well as
vertical directions. They support special characters like Kanji etc., along
with numeric, alphanumeric and binary data. The data encoded in the QR code can
be text, website URL, e-mail address, contact information or SMS.
Barcode is a
machine-readable optical label that contains information about the item to
which it is attached like product packaging or containers. Barcodes can store
information only in the horizontal direction.
QR
Codes vs. Barcodes
·
QR codes have high capacity and can
encode several hundred times as much data as a barcode.
·
QR codes can represent the data in 1/30th
of the space required by a barcode.
·
Supports 360° high speed reading whereas
barcode only supports horizontal reading.
· QR codes can recover up to 30% of
damaged code words whereas reading of damaged barcodes is impossible.
· QR codes can effectively encode Japanese
characters (Kanji) whereas barcodes encode only alphanumeric characters.
The smallest dot of a
QR code is called a module. The resolving power of the cameras used to scan the
code is the determiner of its minimum dimension. However the recommended
minimum size is 32 x 32mm² (1.25 x 1.25inch²). A good contrast between the
colour of the background and the dots is very important in order to ensure good
reader accuracy.
The larger the QR code
the easier it is for it to be scanned. The file formats used for creating a QR
code are – HTML code, PNG file, Tiff file, SVG and EPS. PNG files work well as they
can be easily resized.
Product tracking, item
identification, time tracking, document management, inventory control,
advertising etc., are some of the applications of QR codes.
QR code system includes
a QR code printer and a QR code scanner. To generate QR codes, a special
printer and QR code creation software is required. There are three position
detection patterns – top left, top right and bottom right corners of the
matrix. Factors to be considered while determining the size of a QR code is –
symbol version, data capacity, character type, error correction level and
module size.
·
Symbol
Versions – Symbol versions of QR codes range from 1 (21x 21
modules) to 40 (177 x 177 modules). Each version has maximum data capacity
which depends on the amount of data, type of characters and the error
correction level. Hence, more the data stored, the larger the size of the QR
code.
·
Error
Correction Level – The user can retrieve data from a
damaged QR code with the help of error correction. QR codes have four levels of
error correction – L, M, Q and H – which can be chosen by the user at the time
of creation.
Level
L = 7%
Level
M = 15%
Level
Q = 25%
Level
H = 30%
Higher
error correction level implies increase in percentage of code words used for
error correction and thereby decreases the amount of data that can be stored
inside the code.
·
Character
Type
– The actual amount of characters that can be stored inside the code depends
upon the complexity of the characters.
Limitations
of QR Codes
There is a method named
“attagging” one word for “attack tagging” using which one can combine malicious
QR codes with the reader which can put the user’s contents and privacy at risk.
There is no way to know whether the code is genuine. QR codes can be used to
gain full access to a smart phone. QR codes require connection to the internet
to give information. Another major disadvantage is its dependability on smart
phones, if one does not have a smart phone, QR codes are not at all beneficial
to them and not all phones with camera support the correct reader software.
