A New Low Latency Parallel FIR Filter Scheme

A new array type parallel scheme for an FIR digital filter is presented in this paper. The proposed scheme is based on the structure of the carry-save array multiplier where each cell implements the computation of an FIR filter at the bit-level. This structure leads to latency independent of the number of the filter taps. The proposed scheme is pipelined at the bit-level, is systolic at the cell-level and requires less hardware than other schemes based on discrete multipliers.Paraskevas Kalivas received his Diploma and Ph.D. degree in electrical and computer engineering from the National Technical University of Athens, Greece, in 1990 and 2000 respectively.His research interests include computer arithmetic and efficient realization of arithmetic circuits and digital filters.Vassilis Vassilakis received his Diploma in electrical and computer engineering from NationalTechnical University of Athens, Greece, in 1997. He isworking toward the Ph.D. degree in electrical engineering at National Technical University of Athens.His research interests include efficient circuit implemenation of DSP algorithms and java processor architectures.Chris Meletis received his Diploma in electrical and computer engineering from National Technical University of Athens in 1997. Currently, he is working toward the Ph.D. degree in electrical engineering at National Technical University of Athens.His research interests include multirate filter banks, digital filter design and their efficient realization.Kiamal Z. Pekmestzi received his Diploma in electrical engineering from the National Technical University of Athens, Greece, in 1975. From 1975 to 1981, he was a research fellow in the Electronics Department of the Nuclear Research Center Demokritos. He received his Ph.D. in electrical engineering from the University of Patras, Greece, in 1981.From 1983 to 1985, he was a professor at the Higher School of Electronics in Athens. Since 1985, he has been with the National Technical University of Athens, where he is currently a professor. His research interests include computer arithmetic, VLSI digital filters and VLSI design automation.     

具有任意频响的二维FIR数字滤波器设计的闭式最小二乘解

本文研究具有任意频响特性的二维ＦＩＲ数字滤波器的最小二乘设计问题。     

Linear phase FIR approximation of magnitude response |1/ω| for maximal flatness at an arbitrary frequency ω0, 0<ω0<π*

In many signal processing situations, the desired (ideal) magnitude response of the filter is a rational function: (a digital integrator). The requirements of a linear phase response and guaranteed stable performance limit the design to a finite impulse response (FIR) structure. In many applications we require the FIR filter to yield a highly accurate magnitude response for a narrow band of frequencies with maximal flatness at an arbitrary frequency ₀ in the spectrum (0, ). No techniques for meeting such requirements with respect to approximation of are known in the literature. This paper suggests a design by which the linear phase magnitude response can be approximated by an FIR configuration giving a maximally flat (in the Butterworth sense) response at an arbitrary frequency ₀, 0<₀<^*. A technique to compute exact weights for the design has also been given.     

Efficient linear-phase FIR, maximally flat error approximations for the amplitude response |1/ω r |,r,r=1, 2, 3,..., and a versatile realization

In this paper, designs of linear-phase finite impulse response (FIR) filters approximating the ideal frequency responseH (,r) |1/ ^r r=1, 2, 3,..., by using maximally flat error criteria have been proposed. Exact weights required for the realizations have been derived and are shown to be independent of the filter orderN. The suggested designs are particularly suitable for operation in the midband frequency range of 0.10–0.90 radians.     

采用超分辨率重建提升压缩图像质量的方法

针对JPEG的中低码率压缩图像即高压缩率图像存在较严重的块效应以及量化噪声,提出了一种对JPEG标准压缩图像进行优化的重建-采样方法.该方法对JPEG压缩图像采用三维块匹配算法(BM3D)进行去噪,去除图像中存在的块效应和量化噪声,进而提高超分辨率重建的映射准确性,再使用外部库对去噪后图像进行基于稀疏表示的超分辨率重建,补充一定的高频信息,最后对重建后的高分辨率图进行双三次下采样,得到与原始图像大小一致的图像作为最终优化图像.实验结果表明,该方法在中低码率情况下能够有效地提高JPEG压缩图像的质量,对高码率压缩图像也有一定效果.     

Cascade realization of linear phase fir filters with low sensitivity

The errors due to coefficient quantization in a digital filter are sensitive functions of its pole and zero locations. In this paper, a detailed analysis is made of the sensitivity, with respect to the location of zeros, of elemental fourth-order sections, for cascade realization of linear phase FIR filters. New structures are suggested for the realization of the sections with low sensitivity. Performance analysis of these structures in implementation of a few representative filters indicates their suitability for practical applications.     

On design of a novel class of selective CIC FIR filter functions with improved response

The Cascaded-Integrator-Comb (CIC) filter is a non-recursive (FIR) filter which is multiplier free, consisting only of two building blocks (simple integrator stage and simple comb filter stage) and has a linear phase. This paper summarizes some key points of classical CIC filters and proposes a novel class of CIC FIR filter functions. A novel class of CIC filter functions maintains simplicity of FIR filters by avoiding the multipliers, but shows excellent performances in term of insertion loss in stopband and selectivity with respect to conventional CIC filters. A set of simulations along with illustrative examples is conducted in order to compare the attenuation characteristics of the classical CIC filter functions and the proposed novel class of selective CIC FIR filter functions. For the same level of a constant group delay τ = 45.5 s, a classical CIC filter function has insertion loss of 166.3 dB, and designed novel filter function has a higher level of insertion loss 206.55 dB.     

Optimal McClellan transformation and its application to 2-D FIR digial filter design

A new method to choose the coefficients of the McClellan transformation is developed. The coefficients are obtained by using both analytic and nonlinear optimization approaches. The transformation using the proposed method has much better approximation performance for circular symmetry than the existing methods, especially when the cutoff frequency of the 2-D filter is very large. The proposed method also applies to choose the transformation coefficients to approximate elliptic contours. Two design examples of 2-D FIR digital filters demonstrate the good performance of the proposed method.     

基于针对性字典的压缩图像稀疏超分辨率重建

为了有效地重建压缩低分辨率图像,提出一种基于针对性字典的压缩图像稀疏超分辨率重建算法.首先,根据压缩低分辨率图像的形成特点,对训练库图像进行针对性的下采样压缩编码处理,进行超完备字典的训练;然后,通过训练所得的针对性字典对压缩低分辨率图像进行稀疏表示的超分辨率重建.为进一步恢复图像的高频信息,进行了针对性残差字典训练,并对图像进行高频信息补偿,得到稀疏重建后的图像主观效果更加突出,客观评价参数也得到较大提升.实验结果表明,该算法对压缩图像的超分辨率重建更具针对性,具有良好鲁棒性和高效性.     

Image super-resolution by curve fitting in the threshold decomposition domain

A new curve-fitting scheme is proposed in this paper to produce super-resolution images from a single low-resolution source image. The most unique feature of this method is that the threshold decomposition is performed on the given source image to obtain multiple binary images so that the curve-fitting applied on each resulted binary image can be made very efficient and accurate, thus allowing us to focus on tiny objects and thin structures so as to achieve rather nice visual results even when a large up-scaling factor is used. Two novel techniques are further proposed to improve the visual quality: (1) a spreading technique (applied on some significant pixels detected in each threshold decomposed binary image) is used to remove ladder-like false edges that often appear visually in super-resolution images, and (2) an edge correction (guided by the edge information extracted from the original source image) is used to sharpen all inherent edges. Our results are compared with those achieved by using the state-of-arts techniques, showing the ability of our algorithm to achieve a better visual quality in smooth areas as well as for sharp edges and small objects.     

Prediction Capabilities of Boolean and Stack Filters for Lossless Image Compression

This paper proposes optimal Boolean, stack, and FIR-Boolean hybrid filters for realizing the prediction stage in lossless grey-level image compression. New optimal design procedures for Boolean filters are introduced, where the optimality criterion is the Error Entropy (EE). The use of the EE-optimal and MAE-optimal Boolean and stack filters in the sequential prediction structure is considered, under different instances: global-optimal, block-optimal, adaptive-size-block-optimal and multiresolution. An extensive simulation study is carried out for analyzing and comparing the performances of the newly introduced predictors and various other sequential predictors. The EE-optimal Boolean predictors prove to be the most efficient predictors. More refined filtering structures, such as block-optimal or adaptive-size-block-optimal are suitable for the prediction task when the prediction mask ought to be small. The proposed progressive transmission structure based on optimal Boolean prediction is shown to outperform HINT HINT progressive lossless coding scheme.     

粒子群优化算法在FIR数字滤波器设计中的应用

本文针对有限脉冲响应(FIR)数字滤波器的设计实质上是一个多参数优化问题,提出了一种用粒子群优化算法(PSO)设计FIR数字滤波器的方法.首先将滤波器的设计问题转化为滤波器参数的优化问题,然后利用粒子群优化算法对整个参数空间进行高效并行搜索以获得参数的最优化.FIR数字低通、带通滤波器设计实例证明了该方法的有效性和优越性.     

自适应滤波器并行实现

并行处理是高速实时信号处理领域研究的主要技术,随着信号处理技术的发展,并行处理技术越来越受到人们的重视。本文通过对数字信号进行多项式并行表示,提出了自适应有限冲激响应（ＦＩＲ）滤波器并行实现的几种新方法。作者对这些方法进行了性能分析和比较,狄得了一些有意义的结论。     

Relations between thek-dimensional unconstrained and linear phase FIR Wiener filters

In this note, we show that thek-dimensional linear phase FIR Wiener filter can be obtained from the unconstrained filter with a simple reverse and add operation. The relation between the linear phase and unconstrained phase filters is obtained also in the case of a multichannelk-dimensional system. In this case, the properties of the autocorrelation matrix do not allow the simplifications noted for the single channel case.     

一种基于查找表的FIR成型滤波实现装置

脉冲数字成型滤波器属于有限冲激响应(FIR)滤波器的一种,常规做法是通过传统的乘累加(MACs)方法来实现,即通过对输入信号与单位冲激响应进行线性卷积。但是,随着成型滤波器系数的增加,这种卷积运算势必会占用大量的MAC单元以及延迟单元,导致现场可编程门阵列(FPGA)硬件资源紧张,系统延迟增大,设备成本增加。本文联合了FIR成型滤波器群延时特征以及基带数字调制符号特性,提出了一种新的查找表(LUT)结构的FIR滤波方法,并且在FPGA上实现。软硬件仿真结果表明,这一方法无论从精确度和资源利用上都具有一定的优势。     

A Novel Diversity-Controlled Genetic Algorithm for Rapid Optimization of Bandpass FRM FIR Digital Filters Over CSD Multiplier Coefficient Space

The conventional frequency response masking (FRM) approach is one of the most well-known techniques for the design of sharp transition band finite impulse response (FIR) digital filters. The resulting FRM digital filters permit efficient hardware implementations due to an inherently large number of zero-valued multiplier coefficients. The hardware complexity of these digital filters can further be reduced by representing the remaining (non-zero) multiplier coefficient values by using their canonical signed-digit (CSD) representations. This paper presents a novel diversity-controlled (DC) genetic algorithm (GA) for the discrete optimization of bandpass FRM FIR digital filters over the CSD multiplier coefficient space. The resulting bandpass FIR digital filters are permitted to have equal or unequal lower and upper transition bandwidths. The proposed DCGA is based on an indexed look-up table of permissible CSD multiplier coefficients such that their indices form a closed set under the genetic operations of crossover and mutation. The salient advantage of DCGA over the conventional GA lies in the external control over population diversity and parent selection, giving rise to a rapid convergence to an optimal solution. The external control is achieved through the judicious choice of a pair of DCGA optimization parameters. An empirical investigation is undertaken for choosing appropriate values for these control parameters. The convergence speed advantages of the DCGA are demonstrated through its application to the design and optimization of a pair of bandpass FRM FIR digital filters with equal or arbitrary lower and upper transition bandwidths. In both cases, an increase of about an order of magnitude in the speed of convergence is achieved as compared to the conventional GAs.     

Forward and Reverse Converters and Moduli Set Selection in Signed-Digit?Residue?Number?Systems

This paper presents an investigation into using a combination of two alternative digital number representations; the residue number system (RNS) and the signed-digit (SD) number representation in digital arithmetic circuits. The combined number system is called RNS/SD for short. Since the performance of RNS/SD arithmetic circuits depends on the choice of the moduli set (a set of pairwise prime numbers), the purpose of this work is to compare RNS/SD number systems based on different sets. Five specific moduli sets of different lengths are selected. Moduli-set-specific forward and reverse RNS/SD converters are introduced for each of these sets. A generic conversion technique for moduli sets consisting of any number of elements is also presented. Finite impulse response (FIR) filters are used as reference designs in order to evaluate the performance of RNS/SD processing. The designs are evaluated with respect to delay and circuit area in a commercial 0.13 μm CMOS process. For the case of FIR filters it is shown that generic moduli sets with five or six moduli results in designs with the best area × delay products.

Method for FIR filters design with compressed cosine using Chebyshev's norm

This paper considers a new method for FIR filters design. The method uses an L_∞ optimality norm. To achieve a better approximating effect, a new modulating function which compresses the oscillations of the cosine is proposed. A parameter sets the gradient of the modulating function, with respect to the oscillations’ compression. The approximating polynomial is carried out using Remez’ exchange algorithm. An optimal polynomial with lowest possible (four) degree, that approximates an ideal filter's response with high precision is proposed. With the proposed method a FIR filter with arbitrary specifications can be designed. Design examples of FIR filters with a minimization of calculation are performed. The obtained filter's responses are close to the ideal response. The design examples demonstrate that the proposed approach may be a good alternative in several applications.     

Design of smallest size two-dimensional linear-phase FIR filters with magnitude error constraint

This paper presents an online procedure that produces the smallest feasible size of two-dimensional FIR filters with prescribed magnitude error constraint. The procedure uses the mean square normalized error of constrained and unconstrained least-square filters to produce the initial and the subsequent sizes that converge to the smallest feasible one in a few iterations, where the constrained least-square filters are defined as the least-square filters satisfying the magnitude error constraint. The procedure finally returns a smallest size filter that satisfies the magnitude error constraint and has least total squared magnitude error. Design examples of diamond-shaped, rectangular, and elliptic filters are provided, and comparisons with an exhaustive search are given.