Abstract:

A new divergent block-dependent watermarking method is proposed to authenticate the integrity of the image and localize the image tampers. The divergent block-dependent watermarking method is prior to conventional block-dependent watermarking method with improved security and localization accuracy. the original image is firstly divided into non-overlapping blocks, and then the block watermark is independently generated. the characteristics of the image block is mapped into the initial value of a chaotic map, and the block watermark is generated by iterating the chaotic map from the initial value. In the meantime, a block related to several blocks is made by sorting chaotic sequences to form the divergent block-dependent structure. Then the block watermark is inserted into the least significant bits of the related blocks to obtain the watermarked image. The experiments show that the proposed divergent block-dependent watermarking method can resist to the counterfeiting attack, and localize the tampers correctly and accurately.

Key words: Image authentication, fragile watermarking, block dependent, tamper localization, chaos system