Study Of QR Codes Watermark Technology Based On Simulated Annealing And DWT

Current Quick Response Code has three problems. Firstly, the code rule of QR code has not been properly used when digital watermarking technology is applied to its encryption. Secondly, the maximum amount of embedded watermark information is limited and the robustness is poor. Thirdly, it takes a long time to extract the watermark information. In order to solve the above problems, this thesis studies the features of QR codes chart and coding rules, combining the watermark embedding location with the direction of chain code and LSB (Least Significant Bits) algorithm. Then new QR code watermark embedding and extracting algorithms are suggested, based on SA (simulated annealing algorithm) and DWT (discrete Wavelet Transform) watermarking technology.By combining the LSB algorithm, the direction of the chain codes and basic units of QR codes, we design a scheme for the embedding location and representation of watermark. Then, an algorithm is suggested based on SA and location distribution scheme, through which multiple fingerprint feature information could be embeddable by competitive program. The advantage lies in that it not only achieves the encryption of the watermark embedded position, but also ensures the full use of the fingerprint feature information and rational sampling.When extracting the watermark information, we firstly identify the basic information of QR code, then map out the original image with the basic information based on QR coding rules. Finally, the watermark embedding area is found by image difference of the original image with the watermark image. Our experiments show that the watermark algorithm has a high level of confidentiality, fast extraction speed, high accuracy and resistant to most of the typical attacks. But we have to say that its resistant capability of shear attack is poor.To improve the resistant capability of shear attack, Chapter four proposes an improved scheme by combining the space domain of watermarking algorithm with DWT (wavelet transform) watermarking technology. The algorithm firstly does a DWT transform in the space domain processed watermark image. Then, the processed image is treated as watermark embedded into the HH component obtained by its DWT transform. In this way, the algorithm achieves a nested encryption of the watermark information. The experiments’ results show that our watermarking algorithm has strong capability of shear attack-resistance, and the mutual interference of the watermark is small.