When printing a QR Code the following tips will help you to sustain the readability of your QR Code. Nevertheless always do scan tests before printing QR Codes in a high volume.
Provide enough contrast
The color of the QR code should be different enough from the background color, so that the camera is able to decode the QR Code.
The QR code on the right side distincts too little of the background and is hard to be decoded by a QR Code Reader.
Mind the Quiet Zone around the QR Code
Leave enough quiet zone around the QR Code (about 4 blocks). If the distance between the pixels of the QR Code and the adjacent graphic elements is too small, the QR code can not be decoded. Try to scan the right QR code in the following figure. Your QR Code Reader App will not be able to decipher the code.
The QR Code on the right is unreadable since there is no quiet zone around the QR Code.
Use scale able QR Codes in vector format
Please use EPS QR Codes or download them in any other vector format like .pdf or .svg when printing a QR Code. This ensures that your QR Codes will always stay sharp, no matter which size they have. Other formats like .png may produce a blurred or pixelated outcome when printed. If you insist using the .png format please download the QR Code in a high resolution.
Use vector QR Code to avoid blurring or pixelation
Size does matter
Please be aware of the minimum size of a QR Code. Even if most modern smartphones may read a QR Code with a length less than 5mm this will not be the case for 100% of all phones out there.
Use a size of 20×20 mm for a QR Code to be readable by any smartphone
Logo in a QR Code
If you want to embed a logo into the QR code, always use the error correction level H. With that level a maximum area of 30% of the QR code may be overlaid with a logo.
Preferably use squared logos and center them in the QR code. In the margins of a QR code some important pixels are placed which are necessary for the QR Code Reader app to decode the QR Code and therefore they cannot be overwritten. Even if you stick to the maximum size of the logo, please test the QR Code with multiple QR Code Reader apps for readability. If the QR code cannot be decoded, reduce the size or change the aspect ratio of the logo. The safest version, however, is still a purely black and white QR code.
A maximum of 30% of the QR code can be overwritten with a logo so that it still be readable
Beware of Inverted (Negative) QR Codes
Sometimes a QR Code is better suited to an illustration, if the colors are chosen inversely. That means, that the black pixels of the QR Code are colored white and the background is kept in a dark color. In principle, such inverse or negative QR Codes can be decoded by various QR Code Readers, nevertheless with caution. The QR Code on the right side in the figure could was unreadable for 2 out of 5 tested QR Code readers apps.
Not all QR Code Readers are able to decode inverted QR Codes like shown on the right.
QR Code Reader that decode negative QR Codes
| i-nigma (3G Vision) | yes |
| Qrafter (Kerem Erkan) | yes |
| Quick Scan (iHandy Inc.) | no |
| Scan (Scan Inc.) | yes |
| ZXing (Zing Team) | no |
Avoid Reflective Surfaces
Note especially that when a QR code is affixed behind a glass, reflections may occur, so that the camera can have problems when decoding the QR Code. Print the QR Code beforehand, mount the code at the place where it will be in production and do scanning tests to ensure readability.
Use Dynamic QR Codes!
When you have printed QR Codes on thousands of flyers, posters or in magazines, the worst thing is to find out, that the QR Code redirects to a broken website. In case you have used dynamic QR Codes, you can change the target URL anytime without printing the QR Codes again. To save your budget and nerves: Avoid static QR Codes in your campaigns and always test your QR Codes before going in production!
Further Reading
