Orthogonal dirty paper coding for informed data hiding

摘要

A new dirty paper coding technique for robust watermarking is presented based on the properties of orthogonal codes. By relying on the simple structure of these codes, a simple yet powerful technique to embed a message within the host signal is developed. In addition, the equi-energetic nature of the coded sequence, together with the adoption of a correlation-based decoder, ensures that the watermark is robust against value-metric scaling. The performance of the dirty coding algorithm are further improved by replacing orthogonal codes with Gold sequences and by concatenating them with an outer turbo code. To this aim, the inner decoder is modified so to produce a soft estimate of the embedded message and to make it possible the adoption of an iterative multistage decoding strategy. Performance analysis is carried out by means of Monte Carlo simulations proving the validity of the novel watermarking scheme. A comparison with dirty-trellis watermarking reveals the effectiveness of the new system, which, thanks to its very low computational burden, allows the adoption of extremely powerful channel coding strategies, hence ensuring a very high robustness or, even thanks to the optimum embedding procedure, a low distortion.