7298536
A multistage fast motion estimation scheme for video compression
This paper presents a novel multistage motion estimation (ME) scheme called content adaptive search technique (CAST). The proposed scheme consists of four stages: motion vector field (MVF) prediction, block-based segmentation, motion parameter extraction, and adaptive search strategy. Through pre-processing the MVF of the previous reference frame in the first three stages, CAST extracts the motion parameters for each region. The 4th stage is a combination of various techniques including MV prediction, search area decision and an adaptive fast search algorithm that is adjusted by a mathematical model for the block distortion surface (BDS). Experiment shows that the proposed scheme improves the visual quality, while yielding a faster speed, comparing with the other predictive ME algorithms.
16523105
Region-based rate control and bit allocation for wireless video transmission
In this paper, we propose a joint source-channel region-based rate control algorithm for real-time video transmissions over wireless systems. During the video transmission, the channel throughput available to the video encoder in the wireless systems is inherently variable, due to the retransmission of the error packets using the automatic repeat request (ARQ) error control. The variable data rate of the wireless system is characterized by the packet-level Gilbert two-state Markov Model, the parameters of which are extracted from the statistical properties of the channel information obtained from the wireless channel simulator. The proposed algorithm adopts a fast but effective block-based segmentation method to extract the regions of interest. Unlike traditional bit allocation methods used in the region/content-based rate control, the algorithm exploits the most effective criteria "coding qualities" as quantitative factors to directly control bit allocation among different regions so as to achieve better visual quality in the regions of interest. The computational complexity of the algorithm is low making it suitable for real-time applications. Compared with the MPEG-4 rate control algorithm, our algorithm can effectively enhance the perceptual quality for the regions of interest and significantly reduce the number of frame skipping; thereby, improve the smoothness of the video.
9615760
Asynchronous rate control for multi-object videos
Object-based coding can potentially achieve a higher degree of compression and better visual quality. The objects in a scene are not always synchronous, that is, they have different temporal resolutions. In some applications, it is more efficient to transmit asynchronous objects with different temporal rates so as to achieve a better tradeoff between temporal and spatial resolutions. This requires to balance the qualities of individual objects while ensuring an overall visual quality with a given bit rate. This paper proposes a rate control algorithm for multiple video object encoding, which is suitable for both synchronous and asynchronous transmissions. The algorithm aims to maximize scene quality with an accurate bit rate, while efficiently handling buffer fullness. Using an efficient bit allocation strategy, the algorithm achieves accurate target bit rates, provides good coding quality, and decreases buffer overflow/underflow. The proposed algorithm also allows flexible priority adjustment among multiple objects to ensure overall better visual perception. Designed primarily for asynchronous objects, the algorithm treats the synchronous objects as a special case. Experimental results demonstrate that, when giving suitable asynchronous video object planes rates, the proposed algorithm achieves good temporal-spatial tradeoff while yielding accurate rate regulation and effective buffer control.
47269670
Motion estimation for content adaptive video compression
A multistage motion estimation scheme is proposed. The scheme extracts video characteristics by first performing an online video analysis separately for foreground and background regions. Motion parameters are extracted and passed to the next stage. The next stage includes a mathematical model for the block distortion surface (BDS) that enables the algorithm to accordingly adjust its search technique. The search is performed on a precise search area adaptive to the statistical property of the motion vector prediction error. Due to its self-tuning property, not only does the proposed scheme adapt to scenes by yielding better visual quality but it also yields a lower computational complexity, compared with the other predictive motion estimation algorithms on standard benchmark sequences
4666459
Synchronous and asynchronous multiple object rate control for MPEG-4 video coding
Video scenes containing multiple objects can potentially achieve higher degree of compression and better visual quality with individual coding for each object. Video objects are not always synchronous, implying each object may have a separate temporal resolution. This paper proposes a rate control algorithm for multiple video object encoding. Using a novel bit allocation strategy, the algorithm achieves accurate target bit rate, provides good visual quality, and decreases buffer overflow/underflow. Experimental results for both synchronous and asynchronous multiple video object encoding demonstrate that, when compared with the existing rate control scheme recommended by the MPEG-4 standard, the proposed algorithm provide better temporal-spatial tradeoff with more accurate rate regulation.
28479256
On the simulation, modeling, and performance analysis of an 802.16E mobile broadband wireless access system
2008945
Finger Force Direction Recognition by Principal Component Analysis of Fingernail Coloration Pattern
A method based on principal component analysis of the fingernail coloration pattern is presented to infer fingertip force direction during planar contact. Images from 7 subjects were registered and normalized to each other. Results show that the fingernail coloration patterns are similar for the 7 subjects, but the feature centroids vary. It is concluded that there are common features for all people. But accurate detection of fingertip force direction requires individually calibrated centroids
15422371
Priority assessment of software requirements from multiple perspectives
The development of complex software systems involves collecting software requirements from various stakeholders. Often stakeholder perceptions conflict during the requirements elicitation phase. An effective technique to resolve such a conflict is needed. We presented a framework that prioritizes software requirements gathered from multiple stakeholders by incorporating inter-perspective relationships, which is not addressed by existing priority assessment techniques. We use a relationship matrix to analyze the impact between requirements and facilitate the integration process which assesses their priorities based on their relationships from multiple perspectives. It allows the development team to resolve conflicts effectively and concentrate their valuable time and resources on the critical few requirements from multiple perspectives that directly contribute to high customer satisfaction.
205906582
Polygonal approximation using genetic algorithms
A polygon approximation method based on genetic algorithms is proposed in this paper. In the method, a chromosome is used to represent a polygon and is represented by a binary string. Each bit, called a gene, represents a point on the object curve. The objective function is defined as the integral square error between the given curve and the approximated polygon. Three genetic operators namely selection, crossover and mutation, have been constructed for this specific problem. The proposed method when compared with three existing methods can obtain superior approximation results with less error norm with respect to the original curves.
14112050
Distributed particle simulation method on adaptive collaborative system
Abstract This paper presents a distributed N-body method based on an adaptive collaborative system model. The collaborative system is formed by the distributed objects on a distributed system. The system can be reconfigured during the computation to fully utilize the computing power of the networked hosts. The method is implemented in Java and RMI to support distributed computing in heterogeneous environment. A distributed tree structure is designed for communication-efficient computation of N-body method. The performance test shows satisfactory speedup and portability of the method on both homogeneous and heterogeneous clusters. The collaborative system model can be used in various applications and it is expandable to wide-area environment.