Fragile Watermarking Based on Smoothness for Document Image

A document watermarking algorithm based on smoothness in the equal size square blocks in partitioned document image is proposed. Flippability of a pixel is determined by imposing the Flippability criterion in a 3times3 moving window centered at the pixel. Flippable pixels are replaced with watermarking only in embeddable blocks. Different types of blocks are employed and their ability to increase the capacity is compared. Experiments show that the watermarked document image has good quality and the tampered content can be detected and localized successfully. The proposed scheme can be used for document authentication and detection of integrity.