Abstract
This first decade of twenty-first century is witnessing revolution in the form of memory and network speeds as well as computing efficiencies. Simultaneously, the platform and client diversity base is also expanding, with powerful workstations on one extreme and handheld portable devices, like smart-phones on the other. The range of networks, even if we narrow it down, may end up at optical fiber to EDGE. Still versatile are the clients whose needs evolve with every passing moment. The technological revolution notwithstanding, dealing the accompanying diversity is always a serious challenge that must certainly require some scalable strategies. When it comes to scalability, one is compelled to think of the multiresolution characteristic of wavelets as far as multimedia data is concerned. With the wavelets comes the JPEG2000 standard which has added newer dimensions to the concept of scalability. The scalability challenge is more glaring in the case of applications where disparate and large data is involved. An example application is the area of 3D visualization that requires more than one set of the data. Here, issues like data security, data authentication and data unification then emerge. All these form part and parcel of the field of data hiding. The emergence of the wavelet oriented JPEG2000 codec has brought with it the challenge of when, where and how to hide the data for watermarking or steganography while keeping in view the requirements of hiding capacity, robustness and imperceptibility. Even before the advent of the codec, wavelet transformations were commonplace in the field of signal processing. For the last few years, several techniques to embed data inside a host signal in the wavelet transform domain have been proposed. Few of the methods are compatible with the JPEG2000 standard and that is why one comes across methods exclusively proposed for the codec after the latter's inception. In today's world, data hiding is not limited to just watermarking, steganography or authentication but some nontraditional prospects are also there. One such area is the field of 3D visualization wherein data hiding can be employed as a tool for the synchronous and scalable unification of the disparate data in the JPEG2000 coding pipeline. The rest of this chapter is arranged as follows. Section 2 is dedicated to the background concepts wherein a brief account of the wavelet transformations is being given, followed by the presentation of the salient features of the JPEG2000 codec. After introducing information hiding concepts, Section 3 focuses on the when and where to embed in the JPEG2000 coding pipeline, which leads us to introduce a context level classification of the JPEG2000-based data hiding methods presented in the literature in Section 4. In Section 5 we present an application of the JPEG2000-based data hiding for a scalable and synchronous 3D visualization in a client/server environment. Section 6 sums up this chapter.