New approach for QR code watermarking proposed

Researchers in China say they have developed a new watermarking technology for printed QR codes that they say is more robust than existing approaches.

Writing in the journal Neurocomputing (1 November 2015), the team say that anti-counterfeit watermarks designed for digital QR codes are not suitable for printed QR codes because "after going through a print-scan operation a large proportion of [the] information in watermarked QR image will be damaged."

They propose an alternate to current approaches - known as spatial domain watermarking and transform domain watermarking - based on a technology called discrete wavelet transform (DWT) in which the watermarking 'domain' is divided into multiple channels.

The watermark is detected by an algorithm that measures distortion rates between the channels, and the researchers claim the detection rate is greatly improved "without loss of any barcode information."

A robust watermarking system for printed codes is needed because they are increasingly appearing on various printed items such as train and movie tickets, but]" are easy to be forged," they note. 

"How to embed anti-counterfeiting information into printed QR barcode - and how to improve its security performance - has become a crucial technology in researching and application of QR barcode," they conclude.

An abstract of the research paper is available here.