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We introduce a novel, adaptive image representation using spatially varying wavelet packets (WPs), Our adaptive representation uses the fast double-tree algorithm introduced previously (Herley et al., 1993) to optimize an operational rate-distortion (R-D) cost function, as is appropriate for the lossy image compression framework. This involves jointly determining which filter bank tree (WP frequency decomposition) to use, and when to change the filter bank tree (spatial segmentation). For optimality, the spatial and frequency segmentations must be done jointly, not sequentially. Due to computational complexity constraints, we consider quadtree spatial segmentations and binary WP frequency decompositions (corresponding to two-channel filter banks) for application to image coding. We present results verifying the usefulness and versatility of this adaptive representation for image coding using both a first-order entropy rate-measure-based coder as well as a powerful space-frequency quantization-based (SPQ-based) wavelet coder introduced by Xiong et al. (1993).

This paper addresses several aspects related to the distribution of content. The first aim is to provide an overview of the Universal Multimedia Access (UMA) concept. The primary function of UMA services is to provide the best Quality of Service (QoS) or User experience by either selecting/adapting the content format to meet the playback environment, or adapting the content playback environment to accommodate the content. The second purpose of this paper is to describe how the concept of UMA relates to the emerging MPEG standard, Digital Item Adaptation (DIA), which will become Part 7 of the MPEG-21 standard. An update on the standards activity in this area will be presented. Finally, the third purpose of this paper is to describe the impact that DIA will have on transcoding strategies, where we describe topics that we are currently working on and analyze some areas of future research.This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of Mitsubishi Electric Information Technology Center America; an acknowledgment of the authors and individual contributions to the work; and all applicable portions of the copyright notice. Copying, reproduction, or republishing for any other purpose shall require a license with payment of fee to Mitsubishi Electric Information Technology Center America. All rights reserved. ABSTRACTThis paper addresses several aspects related to the distribution of content. The first aim is to provide an overview of the Universal Multimedia Access (UMA) concept. The primary function of UMA services is to provide the best Quality of Service (QoS) or User experience by either selecting/adapting the content format to meet the playback environment, or adapting the content playback environment to accommodate the content. The second purpose of this paper is to describe how the concept of UMA relates to the emerging MPEG standard, Digital Item Adaptation (DIA), which will become Part 7 of the MPEG-21 standard. An update on the standards activity in this area will be presented. Finally, the third purpose of this paper is to describe the impact that DIA will have on transcoding strategies, where we describe topics that we are currently working on and analyze some areas of future research.

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Abstract-We show that the complete information that is available after an image has been encoded is not just an approximate quantized image version, but a whole set of consistent images that contains the original image by necessity. From this starting point, we develop a set of tools to design a new class of encoders for image compression, based on a set decomposition and recombination of image features. As an initial validation, we show the results of an experiment where these tools are used to modify the encoding process of block discrete cosine transform (DCT) coding in order to yield less blocking artifacts.