15539720
Extrapolated impulse response filter and its application in the synthesis of digital filters using the frequency-response masking technique
Techniques based on the frequency-response masking (FRM) approach are known to be highly effective for reducing the number of multipliers and adders in linear-phase finite-impulse response (FIR) filters. The basic FRM structure comprises a band-edge shaping filter and two masking filters. It is observed that the impulse response of the band-edge shaping filter of an FRM structure exhibits a quasi-periodic property. Previous study showed that lowpass or highpass digital FIR filters, whose impulse responses are quasi-periodic, can be synthesized using extrapolated impulse response technique, which leads to structure with much reduced arithmetic complexity. In this paper, an implementation of the extrapolated impulse response filter is presented. An FRM technique incorporating extrapolated impulse response band-edge shaping filter is introduced. An iterative optimization procedure is proposed to design the FRM sub-filters. It is demonstrated using an example taken from the literature that our new technique produces a saving of over 20% in the number of multipliers used. r 2004 Elsevier B.V. All rights reserved.
15594560
FRM-Based FIR Filters with Minimum Coefficient Sensitivities
A method for optimizing FRM-based FIR filters with optimum coefficient sensitivity is presented. This technique can be used in conjunction with nonlinear optimization techniques to design very sharp filters that do not only have very sparse coefficient values but also very low coefficient sensitivity.
2854649
Frequency-response-masking technique incorporating extrapolated impulse response band-edge shaping filter
Techniques based on the frequency-response masking (FRM) approach are known to be highly efficient for achieving drastic reduction of the number of multipliers and adders in narrow transition band linear-phase finite-impulse response (FIR) filters. Basic FRM structure comprises a band-edge shaping filter and two masking filters. It is observed that the impulse response of the band-edge shaping filter of FRM shows quasi-periodic property. Previous study demonstrated that the quasi-periodic property of the impulse responses of lowpass or highpass digital FIR filters can be exploited to reduce the complexity of the filter by using extrapolated impulse response technique. Extrapolating the idea, the band-edge shaping filter in FRM may be designed by the extrapolated impulse response technique. In this paper, an FRM technique incorporating extrapolated impulse response band-edge shaping filter is introduced. An iterative optimization procedure is proposed to design the FRM subfilters. An example taken from the literature is used to illustrate that the number of multipliers produced by our technique is less than 80 percent of earlier results.
7801331
FPGA implementation of digital filters synthesized using the frequency-response masking technique
The effective length of a filter designed using the frequency-response masking technique is very high and requires a very large number of delay elements. In this paper, we present some useful techniques for reducing the data transfer between the FPGA and external memory when the random logic are implemented using FPGA and the delay elements are implemented using external memory such as DRAM.
17955850
Signed power-of-two allocation scheme for the design of lattice orthogonal filter banks
In signed power-of-two (SPT) coefficient digital filter design, it is well known that a better frequency response performance can be achieved if the number of SPT terms for each coefficient is not limited to a fixed number but instead, is allowed to vary subject to a given number of total SPT terms for the filter. Many SPT term allocation schemes have been developed for distributing the number of SPT terms to the coefficients. In this paper, an SPT term allocation scheme is developed for the design of lattice orthogonal filter banks. The SPT terms are allocated to coefficients one at a time to minimize the frequency response errors due to rounding the coefficients to SPT numbers. Examples show that the proposed allocation scheme is eminently suitable for the design of SPT coefficient lattice filter banks. It is superior to those reported in the literature.
10354510
Using familiar single-user editors for collaborative editing
A number of real-time group editors have been developed as vehicles for investigating various technical issues in computer-supported cooperative work (CSCW). Excellent as they are in serving academic purposes, those research prototypes are not (and will probably not be) widely used by ordinary users for "serious" group editing activities. The reason is primarily that they are generally not as powerful or usable as single-user editors that people are already familiar with. In this paper, we propose an approach which converts existing single-user editors to group editors without modifying their source code. As a result, different editors such as Word and GVim can be shared by a group of distributed users to edit the same document simultaneously. Users can use familiar single-user editors for collaborative editing which are allowed to be heterogeneous. Towards this end we have been working on a research project called intelligent collaboration transparency or ICT to address related technical issues. Our work compared to existing application-sharing systems especially in that it is able to interoperate heterogeneous single-user applications. We report our latest progress on this project.
17708725
An extended fault class hierarchy for specification-based testing
Kuhn, followed by Tsuchiya and Kikuno, have developed a hierarchy of relationships among several common types of faults (such as variable and expression faults) for specification-based testing by studying the corresponding fault detection conditions. Their analytical results can help explain the relative effectiveness of various fault-based testing techniques previously proposed in the literature. This article extends and complements their studies by analyzing the relationships between variable and literal faults, and among literal, operator, term, and expression faults. Our analysis is more comprehensive and produces a richer set of findings that interpret previous empirical results, can be applied to the design and evaluation of test methods, and inform the way that test cases should be prioritized for earlier detection of faults. Although this work originated from the detection of faults related to specifications, our results are equally applicable to program-based predicate testing that involves logic expressions.
123116880
Shadow Graphs and 3D Texture Reconstruction
We present methods for recovering surface height fields such as geometric details of 3D textures by incorporating shadow constraints. We introduce shadow graphs which give a new graph-based representation for shadow constraints. It can be shown that the shadow graph alone is sufficient to solve the shape-from-shadow problem from a dense set of images. Shadow graphs provide a simpler and more systematic approach to represent and integrate shadow constraints from multiple images. To recover height fields from a sparse set of images, we propose a method for integrated shadow and shading constraints. Previous shape-from-shadow algorithms do not consider shading constraints while shape-from-shading usually assumes there is no shadow. Our method is based on collecting a set of images from a fixed viewpoint as a known light source changes its position. It first builds a shadow graph from shadow constraints from which an upper bound for each pixel can be derived if the height values of a small number of pixels are initialized correctly. Finally, a constrained optimization procedure is designed to make the results from shape-from-shading consistent with the height bounds derived from the shadow constraints. Our technique is demonstrated on both synthetic and real imagery.
11448321
Video metamorphosis using dense flow fields
Metamorphosis is generally known as the continu- ous evolution of a source into a target. There is frame-to-frame camera or object motion most of the time when either the source or the target is an image sequence. It would be desirable to make smooth morphing transitions simultaneously along with the origi- nal motion. In this paper, we describe a novel semi-automatic mor- phing technique for image sequences. The proposed technique ef- fectively exploits temporal coherence and automatic image match- ing. One-to-one dense mappings between pairs of corresponding frames are obtained by applying a compositing procedure and a hi- erarchical image matching technique based on dynamic program- ming. These dense mappings can be initialized by sparse frame- to-frame feature correspondences obtained semi-automatically by integrating a friendly user interface with a robust feature tracking algorithm. Experimental results show that our approach to video metamorphosis can produce superior results.
4001661
Configuring common personal software: a requirements-driven approach
We investigate the personalization capabilities of common personal software systems. We use a typical e-mail client as an example of such a system, and examine the configuration screens it offers to its users. We discover that each configuration value reflects each of the ways with which the user goals can be satisfied. Thus, we construct a goal model in which alternative ways for satisfying high level goals are matched with alternative system configurations. This way, automatic configuration of the system by reasoning about the overlaying goal model can be achieved. We find that the vast majority of the configuration options that refer to system functionality can be configured using this method, facilitating thereby the personalization tasks for users with no technical background, and ensuring, at the same time, consistency and meaningfulness in the configuration result.