Watermarking Algorithm Based on Informed Coding and Informed Embedding

Informed coding and informed embedding have received considerable attention as a method of digital watermarking with side information in resent years. We designed a new type of codes called structured dirty-paper trellis in which each message is replaced by amount of alternative vectors. This method is very efficient to prevent brightness scaling. A Viterbi decoder is used in the detecting part to find out the highest correlation path. The correct message will be detected no mater how the brightness has been changed for it has no relativity with brightness. In embedding part, watermarking message is adapted by SNR. The original image is divided into several blocks which are transformed by DCT and the adaptive parameter is calculated based on SNR for each block, then watermarking components with different strength are inserted into some middle- frequency coefficients. The experimental results demonstrate that the watermarks generated with the proposed algorithm in this paper have good imperceptibility and robustness.