Contributions to image and video coding for reliable and secure communications.

摘要

In this thesis, we address algorithms in the areas of image and video coding that aim at assuring reliable and secure communications. This work can be divided into 4 different parts: (i) two-dimensional dependent quantization, (ii) region of interest coding, (iii) multiple description coding, and (iv) watermarking.; The first contribution of the thesis is dedicated to the problem of two-dimensional dependent quantization. Traditional greedy-search algorithms are popular due to their low complexity and low memory consumption, but they are far from optimal due to their dependency in coding. To resolve this problem, we develop an allocation technique that can enable efficient selection of the quantization parameter for each coding unit such that the required memory size and computation time can be significantly reduced, as compared to the exhaustive search approach.; The second part of this thesis studies rate-distortion (RD) modeling for wavelet-based codecs and analytical bit allocation based on the proposed RD model. The proposed algorithm efficiently allocates different numbers of bits to different parts of an image. The proposed scheme provides good estimates of the desired operating parameters with low complexity, e.g., without requiring an explicit generation of all possible RD operating points.; The third portion of the thesis is devoted to the problem of error-resilient coding of images. We present Multiple Description Coding (MDC) as a data compression algorithm that provides efficient loss data recovery technique for robust communication over erasure channels. The performance analysis and simulation results show that the proposed technique provides graceful degradation in the presence of channel erasures. In addition to good error resilience, our approach also provides simple adaptation to the changes in channel behavior by taking into account the proposed RD model during the optimization.; The last part focuses on video watermarking, and shows the development of a security mechanism for digital movie distribution. We determine where to cast and how to insert the watermark such that (i) the watermarked movie will be perceptually indistinguishable from the original one and (ii) the extracted watermark will exist in the watermarked (and attacked) movie.