A DWT-based robust semi-blind image watermarking algorithm using two bands

摘要

Robust image watermarking is the process of embedding an invisible watermark in an image with the purpose of keeping the watermark intact after intentional attacks and normal audio/visual processes. A recent DWT image watermarking paper embeds a PRN sequence as a watermark in three bands, excluding the low pass subband, using coefficients that are higher than a given threshold T_1. During watermark detection, all the coefficients higher than another threshold T_2 are chosen for correlation with the original watermark. In this paper, we extend the idea to embed the same watermark in two bands (LL and HH). Our experiments show that for one group of attacks, the correlation with the real watermark is higher than the threshold in the LL band, and for another group of attacks, the correlation with the real watermark is higher than the threshold in the HH band.