Information Theoretic Bounds For Data Hiding In Compressed Images

Abstract

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 addition of the message signal in a suitable transform domain rather than the spatial domain can significantly increase the channel capacity. We compare the capacities achievable with different decompositions like DCT, DFT, Hadamard, and subband transforms. INTRODUCTION Data hiding or Steganography, is a rapidly growing field with potential applications for copyright protection (watermarking), hiding executables for access control of digital multimedia data, embedded captioning, secret communications, etc. It is therefore of significant interest to have a theoretical estimate of the number of bits that can be hidden in multimedia data. In this paper we provide an information-theoretic approach to estimate the number of bits that can be hidden in still images. Let I be the original (cover) image, to which ..