An intelligent control algorithm on the capacity for information hiding in images

In the context of image based covert communication, it is of major importance to estimate and control the maximum information hiding capacity for a specific image. An adaptive algorithm is presented for maximizing the embedding capacity while achieving specified image fidelity. This algorithm, which makes use of the wavelet transform and, meanwhile, considers the masking characteristics of the human visual system (HVS). In contrast to conventional least significant bit (LSB) steganographic methods operating in the spatial domain, masking is accomplished pixel by pixel by taking into account the texture and the luminance content of all the image subbands. Experimental results show that the proposed algorithm is effective to obtain an estimate of the number of bits that can be hidden in still images, and the algorithm can effectively control the amount of the hidden information adaptively to the requirement of imperceptibility in covert communication.