Multiple-watermarking scheme for the European article-number bar code using adaptive phase-shift keying

This paper reviews the theory of the European article-number barcode (EAN-13) and describes the use of the bar-code pattern as watermarks for embedding into a cover image. The mechanisms that are used to construct a multiple-bar-code watermarking scheme, including the discrete Fourier transform (DFT), adaptive phase-shift keying (APSK), amplitude boost (AB), nearest-phase selection (NPS), and barcode pattern size shrinking (BPSS), are also discussed. Compared with other watermarking techniques, our proposed method has four advantages: (a) We develop a BPSS mechanism to shrink the bar-code size and increase the amount of bar code to be embedded into the cover image. (b) We use the APSK mechanism to determine the phase modulation strength automatically according to the signal magnitude. This decreases the degradation of the cover image enormously. (c) Two strategies-AB and NPS - are used in the scheme. AB enhances the robustness, and NPS improve the imperceptibility. (d) A bar-code pattern error-correcting mechanism is adopted to correct the extracted watermarks. It enhances the robustness greatly. In order to demonstrate the effectiveness of the proposed scheme, simulations under various conditions were conducted. The results show that the proposed scheme can sustain most common attacks, including JPEG compression, rotation, resizing, cropping, painting, noising, and blurring. (c) 2007 Society of Photo-Optical Instrumentation Engineers.