Robust text watermarking based on average skeleton mass of characters against cross-media attacks

The wide spread of digital documents makes it essential to protect intellectual property and information security. As a key method of digital copyright protection, robust document watermarking technology has attracted much attention in this context. With the rapid development of current electronic devices, the ways of document theft are no longer limited to copy and transmission. Due to the convenient and fast shooting operation of the camera on paper or screen, current text watermarking methods need to be robust to cope with cross-media transmission. To realize the corresponding robust text watermarking, a text watermarking scheme based on the average skeleton mass of characters is proposed in this paper, and the average skeleton mass of adjacent characters is used to represent the watermark information. In this paper, a watermarking scheme is designed to modify character pixels, which can modify glyphs without loss of transparency and provide high embedding capacity. Compared with the existing manually designed font-based text watermarking schemes, this scheme does not need to accurately segment characters, nor does it rely on stretching characters to the same size for matching, which reduces the need for character segmentation. In addition, the experimental results show that the proposed watermarking scheme can be robust to the information transmission modes including print-scan, print-camera and screen-camera.