Friday, April 26, 2013

Enter the Quiet Zone

From the movie Flash Gordon: "It's a little too quiet around here for me."

The reference to the quiet zone is related to the QR Code build-up. It has nothing to do with the amount of followers of this blog :-)

The quiet zone together with the 3 specific corner patterns make a QR Code recognizable for a 2D bar-code reader application. Other markers in the QR Code are needed for alignment.

This Quiet zone is easier to explain using a inverted picture of a QR Code. As can be seen in the inverted picture, the actual area required for a QR Code is larger and exceeds the area that actually holds the information content.

In order to find the three QR Code locators in the edges a quiet zone is defined. The size of the quiet zone should be 4 elements wide according to the QR Code specification, and it should have the same color as the 'light' elements.

The inverted QR Code is made to highlight the quiet zone, although there are QR Code Reader Apps that can actually scan/read the inverted code, light and dark inversion is not part of the QR Code specification.

Since not all QR Code readers will be able to handle inverted QR Codes it is advised not to use light/dark inverted codes. For this reason the original code is place here as well.

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