Gao Qi1,Li Renhou1,Wang Huiqin2,Dang Hongmei1,Liu Lianshan1
(1.School of Electronics and Information Engineering,Xi'an Jiaotong University,Xi'an 710049,China;2.Institute of Information and Control,Xi'an University of Architecture & Technology,Xi'an 710055,China)
Abstract:A spread spectrum digital image watermarking algorithm was proposed， in which Gold codes were applied to the structure design of watermark. By exploiting the characteristics that Gold codes have more independent codes, the binary image watermark was modulated with multi-bit binary information regarded as an unit,and then adaptively embedded into low frequency components of the original image in discrete cosine transform domain. Thus,the longer spread spectrum sequences could be used and the robustness accordingly enhanced by utilizing the Gold codes.To reduce the size requirements of the original image,the approximate orthogonality between the Gold codes was considered and the code division multiple access technique was used to compress the data of the modulated watermark signal in the proposed algorithm. Experimental results show that this scheme, compared with algorithms that use m-sequence or orthogonal sequence-pair,is more robust against the typical image processing attacks such as adding noise,filtering and lossy compression.
Keywords:digital watermarking;Gold codes;code division multiple access;discrete cosine transform