We introduce a simple spatially adaptive statistical model for wavelet image coefficients and apply it to image denoising. Our model is inspired by a recent wavelet image compression algorithm, the ...estimation-quantization (EQ) coder. We model wavelet image coefficients as zero-mean Gaussian random variables with high local correlation. We assume a marginal prior distribution on wavelet coefficients variances and estimate them using an approximate maximum a posteriori probability rule. Then we apply an approximate minimum mean squared error estimation procedure to restore the noisy wavelet image coefficients. Despite the simplicity of our method, both in its concept and implementation, our denoising results are among the best reported in the literature.
We explore joint source-channel coding (JSCC) for time-varying channels using a multiresolution framework for both source coding and transmission via novel multiresolution modulation constellations. ...We consider the problem of still image transmission over time-varying channels with the channel state information (CSI) available at (1) receiver only and (2) both transmitter and receiver being informed about the state of the channel, and we quantify the effect of CSI availability on the performance. Our source model is based on the wavelet image decomposition, which generates a collection of subbands modeled by the family of generalized Gaussian distributions. We describe an algorithm that jointly optimizes the design of the multiresolution source codebook, the multiresolution constellation, and the decoding strategy of optimally matching the source resolution and signal constellation resolution "trees" in accordance with the time-varying channel and show how this leads to improved performance over existing methods. The real-time operation needs only table lookups. Our results based on a wavelet image representation show that our multiresolution-based optimized system attains gains on the order of 2 dB in the reconstructed image quality over single-resolution systems using channel optimized source coding.
We address the problem of real-time video streaming over wireless LANs for both unicast and multicast transmission. The wireless channel is modeled as a packet-erasure channel at the IP level. For ...the unicast scenario, we describe a novel hybrid Automatic Repeat reQuest (ARQ) algorithm that efficiently combines forward error control (FEC) coding with the ARQ protocol. For the multiple-users scenario, we formulate the problem of real-time video multicast as an optimization of a maximum regret cost function across the multicast user space. The proposed solution efficiently combines progressive source coding with FEC coding. We present a theoretical analysis of the unicast and multicast cases, as well as experimental results that demonstrate the performance advantages of the proposed algorithms over existing methods.
Improving media services on P2P networks Lienhart, R.; Holliman, M.; Yen-Kuang Chen ...
IEEE internet computing,
2002-Jan.-Feb., 2002-01-00, 20020101, Letnik:
6, Številka:
1
Journal Article
Recenzirano
The Media Accelerating Peer Services system extends P2P infrastructures to improve multimedia services across heterogeneous computing platforms. In this article, we present an architecture and ...resource management and adaptation framework that transcends existing infrastructures to accommodate and accelerate multimedia peer applications and services. We also propose key technology components that support seamless adaptation of resources to enhance quality of service and the building of better tools and applications that utilize the peer-computing network's underlying power.
Factor graph framework for semantic video indexing Ramesh Naphade, M.; Kozintsev, I.V.; Huang, T.S.
IEEE transactions on circuits and systems for video technology,
2002-Jan., 2002, 2002-01-00, 20020101, Letnik:
12, Številka:
1
Journal Article
Recenzirano
Video query by semantic keywords is one of the most challenging research issues in video data management. To go beyond low-level similarity and access video data content by semantics, we need to ...bridge the gap between the low-level representation and high-level semantics. This is a difficult multimedia understanding problem. We formulate this problem as a probabilistic pattern-recognition problem for modeling semantics in terms of concepts and context. To map low-level features to high-level semantics, we propose probabilistic multimedia objects (multijects). Examples of multijects in movies include explosion, mountain, beach, outdoor, music, etc. Semantic concepts in videos interact and appear in context. To model this interaction explicitly, we propose a network of multijects (multinet). To model the multinet computationally, we propose a factor graph framework which can enforce spatio-temporal constraints. Using probabilistic models for multijects, rocks, sky, snow, water-body, and forestry/greenery, and using a factor graph as the multinet, we demonstrate the application of this framework to semantic video indexing. We demonstrate how detection performance can be significantly improved using the multinet to take inter-conceptual relationships into account. Our experiments using a large video database consisting of clips from several movies and based on a set of five semantic concepts reveal a significant improvement in detection performance by over 22%. We also show how the multinet is extended to take temporal correlation into account. By constructing a dynamic multinet, we show that the detection performance is further enhanced by as much as 12%. With this framework, we show how keyword-based query and semantic filtering is possible for a predetermined set of concepts.
We propose a new paradigm for implementations of audio array processing algorithms on a network of distributed general-purpose computers. In contrast to currently existing DSP processor-based ...solutions, our approach offers new possibilities for advanced array signal processing by enabling the usage of general-purpose computing platforms with their superior computational and storage resources. We demonstrate that synchronization of sensors is essential for acoustic blind source separation (BSS) algorithms, and we propose a synchronization scheme that enables BSS on distributed, wirelessly networked computers and can easily be implemented on existing hardware.
The effects of the selective 5-HT1A agonists 8-OH-DPAT and flesinoxan and the selective 5-HT2 antagonists ritanserin and ketanserin on immobility time in rats bred for predisposition to catalepsy ...have been studied. Treatment with 8-OH-DPAT as well as flesinoxan caused a marked dose-dependent decrease in immobility time. Ritanserin and ketanserin did not affect immobility time at any dose tested. It was suggested that 5HT1A rather than 5-HT2 serotonin receptors are involved in the catalepsy and that an hereditary predisposition to catalepsy may be the result of an inherited alteration in 5-HT1A receptors.
Block cyclic redundancy check (CRC) codes represent a popular and powerful class of error detection techniques used almost exclusively in modern data communication systems. Though efficient, CRCs can ...detect errors only after an entire block of data has been received and processed. In this work, we exploit the "continuous" nature of error detection that results from using arithmetic codes for error detection, which provides a novel tradeoff between the amount of added redundancy and the amount of time needed to detect an error once it occurs. We demonstrate how this continuous error detection framework improves the overall performance of communication systems, and show how considerable performance gains can be attained. We focus on several important scenarios: 1) automatic repeat request (ARQ) based transmission; 2) forward error correction (FEC frameworks based on (serially) concatenated coding systems involving an inner error-correction code and an outer error-detection code; and 3) reduced state sequence estimation (RSSE) for channels with memory. We demonstrate that the proposed CED framework improves the throughput of ARQ systems by up to 15% and reduces the computational/storage complexity of FEC and RSSE by a factor of two in the comparisons that we make against state-of-the-art systems.
This paper deals with the application to denoising of a very simple but effective "local" spatially adaptive statistical model for the wavelet image representation that was previously introduced ...successfully in a compression context. Motivated by the intimate connection between compression and denoising, this paper explores the significant role of the underlying statistical wavelet image model. The model used here, a simplified version of the one proposed by LoPresto, Ramchandran and Orchard (see Proc. IEEE Data Compression Conf., 1997), is that of a mixture process of independent component fields having a zero-mean Gaussian distribution with unknown variances /spl sigma//sub s//sup 2/ that are slowly spatially-varying with the wavelet coefficient location s. We propose to use this model for image denoising by initially estimating the underlying variance field using a maximum likelihood (ML) rule and then applying the minimum mean squared error (MMSE) estimation procedure. In the process of variance estimation, we assume that the variance field is "locally" smooth to allow its reliable estimation, and use an adaptive window-based estimation procedure to capture the effect of edges. Despite the simplicity of our method, our denoising results compare favorably with the best reported results in the denoising literature.
This poster will present findings from a study of a shopping assistant prototype with simulated augmented reality information. The goal of the study was to find out the acceptable level of delay in ...presentation of augmented information and the acceptable rate of error of the information presented. Twelve participants interacted with a Samsung Omnia™ smartphone that presented a wine shopping scenario under several levels of delay in showing product information. Participants indicated their willingness to wait for each delay they experienced. Participants also answered a survey about which types of products they would want a shopping assistant application to assist with.
