High-rate quantization data hiding robust to arbitrary linear filtering attacks

Rational Dither Modulation (RDM) is a high-rate data hiding method invariant to gain attacks. We propose an extension of RDM to construct a scheme that is robust to arbitrary linear time-invariant filtering attacks, as opposed to standard Dither Modulation (DM) which we show to be extremely sensitive to those attacks. The novel algorithm, named Discrete Fourier Transform RDM (DFT-RDM) basically works in the DFT domain, applying the RDM core on each frequency channel. We illustrate the feasibility of DFT-RDM by passing the watermarked signal through an implementation of a graphic equalizer: the average error probability is small enough to justify the feasibility of adding a coding with interleaving layer to DFT-RDM. Two easily implementable improvements are discussed: windowing and spreading. In particular, the latter is shown to lead to very large gains.