A watermarking method for printed QR code based on module expansion

Abstract

With the development of the Internet and smart terminals, Quick Response (QR) code and its related applications become increasingly popular. Though there are plenty of advantages for the usage of QR code, but its security issue is always a problem that can not be overlooked. Aiming for embedding message into QR code, a Module Expansion (ME) based method is proposed in this paper. The core idea of ME is to expand a module to its neighbor if these two modules are in different colors. Experimental results show that (1) our capacity for embedding is about half of that for encoding of the same QR code, which is much higher comparing to the state-of-the-art methods, (2) for the QR codes of versions under 20, the average time cost for embedding and extraction is around 51 ms and 59 ms respectively, (3) the success ratio of message extraction under noise attack and print-and-scan process are both higher than 80%. The proposed method can be used in QR code applications such as the anti-counterfeiting for encoded message of a printed QR code, and others for which message sharing is needed.