微处理器的快速开方计算方法

在基于微处理器的自动控制系统中对有效值进行等量计算时,针对利用传统开方算法计算存在速度慢、效率低,对实时控制算法和结果产生不利影响的缺点,提出了一种基于迭代思想的新型开方算法。该算法在使用时先确定计算初值,然后只需进行简单的整数除法等运算即可快速完成开方计算,计算结果具有较高的精度,大幅减少计算周期,提高了计算效率。且该算法不受微处理器内部资源限制,适用于普通8位、16位单片机和DSP等,支持整数开方和浮点开方计算。     

多结构元多路加权形态边缘检测算法研究

边缘检测是图像特征提取与模式识别的基础。形态学边缘检测因其算法简单,噪声抑制和边缘保持能力已成为研究热点。但很多算法采用单一结构元素,很难对弱边界进行有效处理。基于此,利用多结构元思想构造多结构元抗噪型数学形态学边缘检测器,很好地抑制了噪声和提取到弱边缘。     

基于灰度梯度和反正切函数拟合的亚像素边缘检测算法

在数字图像处理和机器视觉中,边缘检测是一个基本问题和关键环节,因此,精确地检测图像边缘是非常必要的。本文提出了一种基于灰度梯度和反正切函数拟合的亚像素边缘检测算法。首先,通过Canny算子粗略提取输入图像的边缘;然后对初步得到的边缘像素逐点提取灰度梯度方向,以提取的梯度方向为坐标轴正方向建立灰度梯度直角坐标系;最后利用最小二乘法,采用反正切函数拟合图像边缘的灰度梯度,获得亚像素边缘位置。利用Microsoft Visual Studio 2008平台进行实验,结果表明：与基于小波变换及基于Zernike矩的亚像素边缘检测方法相比,本文所提算法定位精度较高,检测速度较快,能够更完整地检测出图像的平滑边缘。     

一种新的基于直接最小二乘椭圆拟合的肤色检测方法

肤色检测是计算机视觉中的一个重要问题,本文提出了一种新的基于直接最小二乘椭圆拟合的肤色检测方法,其基本思想是根据肤色样本分布区域的边界数据点采用曲线拟合的方法得到肤色分布区域的边界方程。在实现时,为了解决直接在笛卡儿坐标系中提取肤色样本分布区域边界数据的困难,算法采用了一种新的解决思路,即首先把训练肤色样本在色度空间的统计分布转化为图像的形式,然后再利用边缘检测方法得到肤色分布区域的边界数据。根据所得的边界数据点用直接最小二乘椭圆拟合方法便可得到肤色分布区域的椭圆边界,方法简单直观。实践表明,该算法能完成对各种不同环境条件下所拍摄图像的肤色分割,效果理想,其性能明显优于常用的域值界定法和单高斯模型法。     

Floating-point division and square root using a Taylor-series expansion algorithm

Hardware support for floating-point (FP) arithmetic is a mandatory feature of modern microprocessor design. Although division and square root are relatively infrequent operations in traditional general-purpose applications, they are indispensable and becoming increasingly important in many modern applications. Therefore, overall performance can be greatly affected by the algorithms and the implementations used for designing FP-Div and FP-Sqrt units. In this paper, a single-precision fused floating-point multiply/divide/square root unit based on Taylor-series expansion algorithm is proposed. We extended an existing multiply/divide fused unit to incorporate the square root function with little area and latency overhead since Taylor's theorem enables us to compute approximations for many well-known functions with very similar forms. The implementation results of the proposed fused unit based on standard cell methodology in IBM 90 nm technology exhibits that the incorporation of square root function to an existing multiply/divide unit requires only a modest 18% area increase and the same low latency for divide and square root operation can be achieved (12 cycles). The proposed arithmetic unit exhibits a reasonably good area-performance balance.     

用Prewitt算子细化边缘

传统的边缘检测算予一般都只能得到比较宽的边缘,这为以后的图像处理带来了一定的困难。本文通过对图像边缘特征的分析,提出了一种新的边缘细化方法——Prewitt算子细化边缘。实验表明,这种方法能在保持原有信息的前提下,给出令人满意的细化结果。     

基于DSP的基本函数快速计算

在许多数字信号处理中,一般都会有实时性的要求,在满足计算精度条件下,函数的运算速度非常重要。在DSP上实现基本函数的计算方法有多种,通过设计一个简单的查表电路,可以用查表法快速计算函数值,此电路也使函数表的空间扩展不受DSP存储器空间限制。另外,还给出了三角函数、自然对数和平方根函数表的制作方法以及用查表法求基本函数值的过程。     

Decimal SRT Square Root: Algorithm and Architecture

Given the popularity of decimal arithmetic, hardware implementation of decimal operations has been a hot topic of research in recent decades. Besides the four basic operations, the square root can be implemented as an instruction directly in the hardware, which improves the performance of the decimal floating-point unit in the processors. Hardware implementation of decimal square rooters is usually done using either functional or digit-recurrence algorithms. Functional algorithms, entailing multiplication per iteration, seem inadequate to use for decimal square roots, given the high cost of decimal multipliers. On the other hand, digit-recurrence square root algorithms, particularly SRT (this method is named after its creators, Sweeney, Robertson, and Tocher) algorithms, are simple and well suited for decimal arithmetic. This paper, with the intention of reducing the latency of the decimal square root operation while maintaining a reasonable cost, proposes an SRT algorithm and the corresponding hardware architecture to compute the decimal square root. The proposed fixed-point square root design requires n+3 cycles to compute an n-digit root; the synthesis results show an area cost of about 31K NAND2 and a cycle time of 40 FO4. These results reveal the 14 % speed advantage of the proposed decimal square root architecture over the fastest previous work (which uses a functional algorithm) with about a quarter of the area.     

Valley operator for extracting sketch features: DIP

A new valley operator is presented for extracting sketch features which contain valleys and edges subject to local intensities. It is a very simple operator using local probabilities in a 3×3 local window. Experimental results show its excellent performance compared with existing valley or edge operators     

平方根变步长lp范数LMS算法的稀疏系统辨识

针对稀疏未知系统的辨识问题,提出了一种基于lp(0相似文献   

Edge detection in medical images using a genetic algorithm

An algorithm is developed that detects well-localized, unfragmented, thin edges in medical images based on optimization of edge configurations using a genetic algorithm (GA). Several enhancements were added to improve the performance of the algorithm over a traditional GA. The edge map is split into connected subregions to reduce the solution space and simplify the problem. The edge-map is then optimized in parallel using incorporated genetic operators that perform transforms on edge structures. Adaptation is used to control operator probabilities based on their participation. The GA was compared to the simulated annealing (SA) approach using ideal and actual medical images from different modalities including magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound. Quantitative comparisons were provided based on the Pratt figure of merit and on the cost-function minimization. The detected edges were thin, continuous, and well localized. Most of the basic edge features were detected, Results for different medical image modalities are promising and encourage further investigation to improve the accuracy and experiment with different cost functions and genetic operators     

A class of square root and division free algorithms andarchitectures for QRD-based adaptive signal processing

The least squares (LS) minimization problem constitutes the core of many real-time signal processing problems, such as adaptive filtering, system identification and adaptive beamforming. Recently efficient implementations of the recursive least squares (RLS) algorithm and the constrained recursive least squares (CRLS) algorithm based on the numerically stable QR decomposition (QRD) have been of great interest. Several papers have proposed modifications to the rotation algorithm that circumvent the square root operations and minimize the number of divisions that are involved in the Givens rotation. It has also been shown that all the known square root free algorithms are instances of one parametric algorithm. Recently, a square root free and division free algorithm has also been proposed. In this paper, we propose a family of square root and division free algorithms and examine its relationship with the square root free parametric family. We choose a specific instance for each one of the two parametric algorithms and make a comparative study of the systolic structures based on these two instances, as well as the standard Givens rotation. We consider the architectures for both the optimal residual computation and the optimal weight vector extraction. The dynamic range of the newly proposed algorithm for QRD-RLS optimal residual computation and the wordlength lower bounds that guarantee no overflow are presented. The numerical stability of the algorithm is also considered. A number of obscure points relevant to the realization of the QRD-RLS and the QRD-CRLS algorithms are clarified. Some systolic structures that are described in this paper are very promising, since they require less computational complexity (in various aspects) than the structures known to date and they make the VLSI implementation easier     

基于数学形态学的灰度图像车牌字符提取算法

在深入研究数学形态学的基础上,提取了一种灰度图像车牌字符提取算法。该算法构造4种结构元素,采用数学形态学的膨胀和腐蚀算子依次求出梯度算子对车牌字符进行边缘检测处理和迭代阈值分割,最后结合数学形态学的区域填充方法弥合字符中的空隙。与传统边缘检测算子相比较,实验结果表明该算法具有较强的提取字符能力和良好的抗噪能力,并保护了字符的边缘。其计算量小,在保证处理效果的同时,保证了处理速度,具有一定的可用性和可行性。     

自适应平方根球型无迹卡尔曼滤波算法

针对传统无迹卡尔曼滤波器存在跟踪精度低、数值稳定性差、鲁棒性弱等缺点, 提出了一种基于球型无迹变换的自适应平方根UKF滤波算法（Adaptive Square Root UKF Filtering Algorithm Based on Spherical Unscented Transform, ASRS-UKF）。该算法在标准的平方根UKF算法上,首先改用了球型无迹变换对权系数以及sigma点进行计算选取;其次改进了平方根UKF中平方根矩阵的分解方法;同时在预测误差协方差矩阵中引入了自适应衰减因子。最后,通过将该算法同平方根UKF以及强跟踪UKF算法进行仿真对比,结果表明,ASRS-UKF算法在减少计算量、加快计算速度的同时还提高了滤波精度和稳定性,而且对于系统模型匹配不佳的情况下,仍具有良好的跟踪性能。     

对大整数n=pq分解的一个有效的搜索算法

本文通过构造一个简单的基于调差思想的搜索算法和一个快速的开方算法对满足一定条件的大整数n=pq(p、q为大素数 )进行快速分解 .从而指出基于因子分解的密码体制中存在着相当多的弱密钥 ,而且很难避免选取这些弱密钥 .这对于我们分析基于因子分解的公钥体制的安全性是很有意义的     

An optimal multiedge detector for SAR image segmentation

Edge detection is a fundamental issue in image analysis. Due to the presence of speckle, which can be modeled as a strong, multiplicative noise, edge detection in synthetic aperture radar (SAR) images is extremely difficult, and edge detectors developed for optical images are inefficient. Several robust operators have been developed for the detection of isolated step edges in speckled images. The authors propose a new step-edge detector for SAR images, which is optimal in the minimum mean square error (MSSE) sense under a stochastic multiedge model. It computes a normalized ratio of exponentially weighted averages (ROEWA) on opposite sides of the central pixel. This is done in the horizontal and vertical direction, and the magnitude of the two components yields an edge strength map. Thresholding of the edge strength map by a modified version of the watershed algorithm and region merging to eliminate false edges complete an efficient segmentation scheme. Experimental results obtained from simulated SAR images as well as ERS-1 data are presented     

Improved Bidirectional-Mode Expansion Propagation Algorithm Based on Fourier Series

In this paper, an improved version of a 2-D bidirectional eigenmode expansion propagation algorithm based on Fourier series expansion for modeling optical field distribution in waveguide devices is presented. The algorithm is very simple, numerically robust, and inherently reciprocal. It does not require root searching in the complex plane. Proper truncation rules are used to ensure good convergence properties for TM-polarized waves. Perfectly matched layers as absorbing boundary conditions can be implemented in a very simple way using complex coordinate stretching. The approach represents a transition between purely modal and Fourier expansion methods for modeling guided-wave photonic structures.     

图像边缘检测技术研究

边缘检测技术是图像处理和计算机视觉等领域最基本的技术,如何快速、精确的提取图像物体的边缘信息一直是国内外研究的热点,介绍了几种的经典边缘检测算子,对其性能和算法特点进行了分析。运用Matlab进行了算法的仿真,并对其结果进行了研究和探讨。     

多结构抗噪膨胀-腐蚀型数字灰度图像边缘检测的研究

传统的边缘检测方法对噪声敏感,抑制噪声能力差,经典的形态学边缘检测方法虽然具有较好的去噪能力,但不能反映全部的边缘特性.为此本文提出了一种改进的多结构抗噪膨胀腐蚀型数字灰度图像边缘检测算子.通过仿真结果比较,该算了在检测图像真实边缘和抗噪性能上均优于传统的边缘检测算子.