1533691
Generalized optimum dynamic bit allocation scheme for source compression
Dynamic bit allocation directly impacts the overall coding performance in block transform (e.g., DCT, Hadamard, etc.) coding, subband coding, and wavelet coding. In very low bit rate coding (such as the evolving MPEG-4 standard), additional factors impacting the bit allocation process need to be identified and properly exploited to achieve optimal coding performance. In the paper, a generalized optimum dynamic bit allocation algorithm is presented. The algorithm is based on the Shannon rate-distortion bound and a weighted distortion criterion using a Lagrange multiplier optimization technique. The results look promising for applications in real-time multimedia communications.<<ETX>>
8062529
H.264-based Multiple Description Video Coder and Its DSP Implementation
In this paper, a novel H.264-based multiple description coding (MDC) framework, called the prediction-based spatial polyphase transform (PSPT) multiple description video coding, is introduced to enhance the error-resilience ability and reduce the computational complexity of the H.264 codec. The proposed PSPT-MDC down-samples each input frame in both the horizontal and the vertical directions, forming four subframes. Instead of directly coding and transporting all the four subframes, two of them are predicted from the other two subframes. The proposed H.264-based PSPT-MDC video codec is then implemented on the TI TMS320C6416 digital signal processor with some optimizations to demonstrate its feasibility and attractive performance, in terms of the decoded video quality and error-resilience capability.
6008738
Noise adaptive soft-switching median filter
Existing state-of-the-art switching-based median filters are commonly found to be nonadaptive to noise density variations and prone to misclassifying pixel characteristics at high noise density interference. This reveals the critical need of having a sophisticated switching scheme and an adaptive weighted median filter. We propose a novel switching-based median filter with incorporation of fuzzy-set concept, called the noise adaptive soft-switching median (NASM) filter, to achieve much improved filtering performance in terms of effectiveness in removing impulse noise while preserving signal details and robustness in combating noise density variations. The proposed NASM filter consists of two stages. A soft-switching noise-detection scheme is developed to classify each pixel to be uncorrupted pixel, isolated impulse noise, nonisolated impulse noise or image object's edge pixel. "No filtering" (or identity filter), standard median (SM) filter or our developed fuzzy weighted median (FWM) filter will then be employed according to the respective characteristic type identified. Experimental results show that our NASM filter impressively outperforms other techniques by achieving fairly close performance to that of ideal-switching median filter across a wide range of noise densities, ranging from 10% to 70%
29981324
Accurate optical flow estimation using adaptive scale-space and 3D structure tensor
Computing optical flow for image sequences is often an essential step to many image processing and computer vision applications. In this paper, a novel, unified optical flow estimation method is developed for simultaneously tackling the aperture problem and multiple motions, and consequently, yielding more accurate optical flow estimation. By integrating Gaussian scale-space with 3D structure tensor, the estimation difficulty encountered in multiple motions resulting from multiple video objects has been handled reasonably well. The obtained normal flow is then treated separately from the real flow, by further applying the least-squares estimation, with the assist of the automatic scale selection mechanism, to produce the estimated real flow. Our proposed automatic scale selection for spatial scale-space is developed from the viewpoint of numerical stability, and the condition number is exploited for adaptively choosing local scales (window sizes). For performance evaluation, we adopted the angular error as the quantitative measurement and used several benchmark image sequences. Experimental results show that the accuracy of our optical flow estimation method is superior to several leading algorithms.
7144957
Modeling two-windows TCP behavior in differentiated services networks
Two important issues in assured services within differentiated services architecture are bandwidth guarantee and fair sharing of unsubscribed bandwidth among TCP flows with and without bandwidth reservations. Although the subscribed bandwidth can be guaranteed by increasing network capacity or deploying strict admission control mechanisms, the costs of such solutions are very high. The issue of fair sharing of excess bandwidth is also not well solved. To address those issues, a modified TCP, named two-windows TCP, has been proposed. The performance of the protocol is evaluated by simulations. But its effectiveness is not validated theoretically under general network conditions, which is important for understanding the benefits and costs of using the protocol. In this paper, an analytical model is developed for the purpose. The model characterizes throughput of individual two-windows TCP flow as a function of contract rate, round trip time, loss rates of In and Out packets. Extensive simulations validate the analytical model. It's shown two-windows TCP is effective not only on solving the issues of bandwidth guarantee and fair sharing of unsubscribed bandwidth, but also on increasing the utilization of bottleneck link bandwidth. Moreover, its performance is robust to network conditions, which is important for wide deployment over Internet.
6762785
A new diamond search algorithm for fast block-matching motion estimation
Based on the study of motion vector distribution from several commonly used test image sequences, a new diamond search (DS) algorithm for fast block-matching motion estimation (BMME) is proposed in this paper. Simulation results demonstrate that the proposed DS algorithm greatly outperforms the well-known three-step search (TSS) algorithm. Compared with the new three-step search (NTSS) algorithm, the DS algorithm achieves close performance but requires less computation by up to 22% on average. Experimental results also show that the DS algorithm is better than the four-step search (4SS) and block-based gradient descent search (BBGDS), in terms of mean-square error performance and required number of search points.
5064603
The ascending star subgraph decomposition of some star forests