Anti-counterfeiting digital watermarking algorithm for printed QR barcode

Anti-counterfeiting watermarking technology provides a potential way to prevent quick response (QR) barcode from being copied or forged, and many relevant algorithms for digital QR barcode appeared recently. However, as for printed QR barcode, there is no actual research achievement published. This paper studies anti-counterfeiting techniques for printed QR barcode. The primary performance parameter, decoding rate of QR barcode as well as detection rate of digital watermark, is defined and discussed. A multi-channel robust watermarking scheme based on discrete wavelet transform (DWT) is proposed. In the watermarking scheme, the DWT domain is divided into non-overlapping rectangular areas as called watermarking channels. Channel watermark as well as anti-counterfeiting watermark is embedded into each watermarking channel. At the stage of anti-counterfeiting watermark extracting, the distortion rates of the watermarking channels are estimated by channel watermark. Based on the distortion rates, anti-counterfeiting watermark is computed by a well-designed linear estimation algorithm, whose validity is theoretically proved by analyzing anti-counterfeiting watermark bit error. The experimental results show that the detection rate of anti-counterfeiting watermark is greatly improved with the proposed scheme, and that we can correctly extract anti-counterfeiting watermark from printed QR image by choosing reasonable parameters.