Multi-block dependency based watermarking scheme for binary-text image authentication

To improve the ability against different counterfeiting attacks, a watermarking algorithm is proposed for binary-text image (BTI) authentication. To protect the uniform regions in BTI, the watermark information of a fixed-size block is generated according to the content of it and divided into three parts. One part is embedded in the flippable pixels of itself, and the other two parts are respectively embedded in the flippable pixels of other two blocks in BTI, which are randomly chosen based on the secret key. This strategy can not only introduce the block-wise dependence, but also make it possible for the authentication watermark of a uniform block to be embedded in the BTI. In the tamper detection stage, a multi-block based statistic detection method is designed to verify the validity of an image block. Simulation results show that the proposed algorithm can achieve a good imperceptibility and have an ability resisting the maliciously attacks such as collage attack, delete tampering, replace tampering etc.