A QR or Quick Response code is a two-dimensional barcode. These are often used for adding web links to a printed page. When you scan such a QR bar code using a web cam or mobile phone camera, the QR reader application takes you to a Web site, a YouTube video or some other web content. QR codes are an easy way of sending people to a site without having to type a URL.
Next to being used for linking to share links, QR codes can contain other types of information:
- A QR code on a business card can contain an electronic version of thecontact information. Scan the code and the reader application adds the contact to your address list.
- A QR code can contain event information. Scan the code on a poster for a concert and the app automatically adds its name, date and location to the agenda on your smartphone or PC.
- A QR code can contain an SMS with phone number and text. Scan the code and the scanning app lets you automatically participate in some contest to win fabulous prices.
- A QR code can contain an e-mail message with a subject and message text. That message can be a request for information so that in return you might get a reply email with additional information and attached files.
- A QR code can contain a geographical location. Scan the code on a poster advertising for a restaurant and its location becomes available to your navigation software, informing you how to get to that place.
- A QR code can contain WIFI configuration data. Scan the code and your Android device automatically configures itself to use the wireless access at the hotel.
Description of Quick Response bar codes
The Japanese corporation Denso-Wave created the QR matrix code in 1994. It is an open standard for which no license fee has to be paid. The physical encoding of QR codes is nowadays in the hands of various standards bodies, including JIS and ISO (e.g. the ISO/IEC 18004:2006 standard). The standard for encoding URLs was established by NTT docomo, the Japanese telecom company.
QR codes contain information in both the horizontal and vertical axis. Compared to ‘regular’ barcodes, this allows for much larger amounts of raw data to be embedded. These can be numeric, alphanumeric or binary data – of which up to 2953 bytes can be stored. Only a part of each QR bar code contains actual data, including error correction information. Below you see the above QR code with the URL data stripped away. As you can see quite a large area of the bar code is used for defining the data format and version as well as for positioning, alignment and timing purposes.
The more data need to be embedded, the larger the barcode becomes. Below is the QR code for this page. Since the URL is longer than that of the home page, the bar code has also grown. The barcode after it doesn’t contain a URL but the first 5 sentences of this page.
The smallest square dot or pixel element of a QR code is called a module. Like with other types of bar codes, it is recommended to have an empty area around the graphic, which makes it easier for devices to read the bar code. This quiet area is ideally 4 modules wide.
The minimum dimensions of a QR code depend upon the resolving power of the cameras that are used to scan the code. According to a Kaywa white paper, it is recommended to use a minimum size of 32 × 32 mm or 1.25 × 1.25 inches, excluding quiet zone, for QR codes that contain a URL. This guarantees that all camera phones on the market can properly read the bar code. Changing the size to a width and height of 26 × 26 mm or roughly 1 square inch still covers 90% of the phones on the market. The latest camera models, which have improved macro capabilities, can however already deal with QR codes that are less than 10 mm (0.4″) wide and high.
For good reader accuracy good contrast between the background and the bar color itself is very important. The bar code should have a dark color on a light background. You cannot go wrong by treating the QR code as line art, using black on white. If the background needs to be in color, make sure that it is a solid color, not a screened tint. Avoid using cyan or magenta but a 100% yellow background should work fine. Very light Pantone colors might also work, as long as the contrast with the bar code is high enough.
How to read a QR code
To read a a hardlink or physical world hyperlink, a smartphone or computer equipped with a web cam needs to have the correct reader software. It will interpret the scanned image and launch a browser to visit the programmed URL. Do a web search using the keywords “QR reader” and the make of your phone to find such applications.
Some interesting links: