The quiet zone is a part of the QR code. It is defined in the following way in the QR code spec:
“This is a region 4X wide which shall be free of all other markings, surrounding the symbol on all four sides. Its nominal reflectance value shall be equal to that of the light modules.”
The X mentioned above refers to the width of a dark module (which should be same as the width of a bright module), 4X means width of 4 modules.
The quiet zone is an area that should be taken into account when calculating the print size of your QR code on any printed media. According to the spec a version one QR code will take on print twice the area of the QR code itself due to its quiet zone. Technology however may change this. What if all readers work fluently with 2X quiet zone? Area after all is a central factor when it comes to print – do we have to comply to specs when technology allows us to bend them or even ignore them? Is there a new quiet zone rule that we can stick to and if there is what the relevant new quiet zone area is?
First tests with quiet zone
Here are three QR codes the left one has a 4X quiet zone area and the right one has 1X quiet zone and 2X quiet zone in the middle . Below are tests results of various readers on iPhone and Android devices, I assume that the same readers will perform similarly in other platforms like Blackberries Symbian and Windows phones – where they exist.
As you can see all readers have no problem to scan a 1X quiet zone QR code. So there is no need any more for anything more than 1X quiet zone.
The question is – can we go further? Can we go inside the 1X quiet zone and still get a readable QR code?
Invading the quiet zone
In the left is the same QR code with 1X quiet zone where the quiet zone here is violated once in each direction without destroying original QR code data. In the middle is the same QR code but here the 1X quiet zone is violated around the finder patterns. The right QR code has a quiet zone violation that encircles the finders without violating the quiet zone for the finders themselves.
The last QR code has a high EC to help it recover the corrupted data.
The reader results follow.
When only one reader had a problem to scan the codes in the left and in the right, more than half of them could not read the middle code where the finding patterns quiet zone was violated. It is interesting to see that almost all readers (except one) do not need a fully surrounding 1X quiet zone when the spec requires a 4X surrounding quiet zone.
This means that not only a 1X fully surrounding quiet zone is all what QR code needs today, it means also that this 1X quiet zone must not encircle fully the whole QR code. What is really important is giving the finder patterns a 1X quiet zone and nothing more. Going down from a 4X quiet zone to 1X quiet zone around the finders only is a huge space saving. Use that space to increase your QR code on print or alternatively – your QR code will consume a much smaller printing area!
To make sure that only the finder patterns needs a quiet zone for practically all readers here is an extreme example of QR code where only the finder patterns quiet zone exists.
Checking this code with all the readers above will show the same results we got for the right QR code in previous example. So not only 1X quiet is enough but this 1X quiet zone can be limited only to the finder patterns of the QR code. Not only it saves print area, it also permits new kinds of decorated QR codes.