title: Capacity estimates for data hiding in compressed images.
abstract: In this paper, we present an information-theoretic approach to obtain an estimate of the number of bits that can be hidden in still images, or, the capacity of the data-hiding channel.We show how the addition of the message signal or signature in a suitable transform domain rather than the spatial domain can significantly increase the channel capacity. Most of the state-of-the-art schemes developed thus far for data-hiding have embedded bits in some transform domain, as it has always been implicitly understood that a decomposition would help. Though most methods reported in the literature use DCT or wavelet decomposition for data embedding, the choice of the transform is not obvious.We compare the achievable data-hiding capacities for different decompositions like DCT, DFT, Hadamard, and subband transforms and show that the magnitude DFT decomposition performs best among the ones compared.
authors.affiliation: IDT Corp., Newark, NJ 07102, USA. ramkumar@corp.idt.net
authors.forename: M
authors.initials: M
authors.lastname: Ramkumar
authors.forename: A N
authors.initials: AN
authors.lastname: Akansu