Data hiding in multimedia - theory and applications

Multimedia data hiding or steganography is a means of communication using subliminal channels. The resource for the subliminal communication scheme is the distortion of the original content that can be tolerated. This thesis addresses two main issues of steganographic communication schemes: 1. How does one maximize the distortion introduced without affecting fidelity of the content? 2. How does one efficiently utilize the resource (the distortion introduced) for communicating as many bits of information as possible? In other words, what is a good signaling strategy for the subliminal communication scheme? Close to optimal solutions for both issues are analyzed. Many techniques for the issue for maximizing the resource, viz, the distortion introduced imperceptibly in images and video frames, are proposed. Different signaling strategies for steganographic communication are explored, and a novel signaling technique employing a floating signal constellation is proposed. Algorithms for optimal choices of the parameters of the signaling technique are presented. Other application specific issues like the type of robustness needed are taken into consideration along with the established theoretical background to design optimal data hiding schemes. In particular, two very important applications of data hiding are addressed - data hiding for multimedia content delivery, and data hiding for watermarking (for proving ownership). A robust watermarking protocol for unambiguous resolution of ownership is proposed

On The Implementation Of 2-Band Cyclic Filterbanks

The concept of cyclic filter banks was introduced independently in Ref. [1] and [2], though in [1], a different nomenclature was used. "Cyclic filter banks" is a superset of the traditional non-cyclic filter banks, and readily suggest implementation of subband filtering through DFT. In this paper we show that the DFT implementation is also advantageous for the conventional FIR filter banks. The discussions in this paper concentrate on the more frequently used 2-band decompositions. However, extensions to M bands is not difficult. 1. INTRODUCTION A concise theory of cyclic filter banks was presented in Ref [2]. In the traditional M-band, FIR perfect reconstruction (PR) filter banks, all the M filters are orthogonal to linear shifts by M.In cyclic filter banks on the other hand, the filters are orthogonal to cyclic shifts. As filters orthogonal to linear shifts are also orthogonal to cyclic shifts, cyclic filter banks have more degrees of freedom than the traditional FIR PR filter bank..