An anti-geometric digital watermark algorithm based on histogram grouping and fault-tolerance channel

Nowadays there exist many kinds of robust image watermark algorithms. However, most of them are invalid even when the carrier suffers from slight geometric attacks. To address the problem, an anti-geometric attack digital watermark algorithm based on the statistical characters of image histogram is proposed. The fault-tolerant channel is introduced to weaken or eliminate the interference caused by geometric distortion to the image when the watermark is embedded. To do this, the algorithm compares and adjusts image pixel distribution in the fixed grayscale intervals dynamically. Experiments show that our algorithm has low computational cost, good invisibility and perfect robustness in against rotating, translating, scaling and common noise attacks. Meanwhile the embedded watermark can be easily and exactly fetched.