A geometrical attack resistant image watermarking algorithm based on histogram modification

摘要

In order to avoid geometric distortions in watermark embedding, a geometrical attack resistant image watermarking algorithm is proposed based on histogram modification. The watermark information is embedded into the host image by modifying the number of the gray samples of the image histogram. In a fixed gray range, every three consecutive bins are divided into a group for embedding one-bit watermark, through modifying the sample value of a bin to another of the adjacent bin to realize the watermark insertion. Moreover, to avoid duplicate modification and improve the transparency, only one bin is modified every two neighbor bins, the modified histogram is mapped into the watermarked image. For watermark detection, it is in fact an inverse process of watermark embedding. Watermark is extracted through calculating and judging the relationship of the number of samples of the three successive bins. The experimental results show that the algorithm is robust to both geometrical attacks and those conventional signal processing attacks.