A chaos-based scramble self-embedding watermarking algorithm was proposed to locate tamper block on the wa- termarked images and improve security of the existing self-embedding fragile watermarking algorithms that could not effec- tively locate tamper block. In proposed algorithm

the binary watermark image was generated from the watermark blocks putted together according to their positions

and the improved security binary watermark scrambled by chaotic systems was embedded into the LSB of the image data. While image authentication

the block of tampered content could be effectively localized according to the predefined threshold. Theoretic analysis and simulation results show that the proposed algorithms may not only improve security

but it also effectively locates tamper blocks whether watermark is altered or not.