Information embedding with reversible stegotext

Abstract

Information embedding is the transmission of an independent data embedded into a host signal via a noisy channel. Reversible information embedding (RIE) extends this model by adding the requirement of decoding the host signal. In some applications however, this requirement is too strong. For example, if the user is interested in decoding the data and further transmitting the stegotext, i.e. the result of the embedding of independent data into the host, then full decoding of the host is not needed, only re-production of the stegotext. This work expands the study of information embedding channels by adding the requirement of retrieving the stegotext at the destination. A single-letter characterization of the achievable rate-distortion region is developed. In particular, it is shown that a rate higher than the RIE rate can be achieved, under the (more relaxed) requirement of stegotext decoding. Two examples are solved, and an iterative algorithm that computes numerically the capacity is provided.