A class of adaptive directional image smoothing filters

The gray level distribution around a pixel of an image usually tends to be more coherent in some directions compared to other directions. The idea of adaptive directional filtering is to estimate the direction of higher coherence around each pixel location and then to employ a window which approximates a line segment in that direction. Hence, the details of the image may be preserved while maintaining a satisfactory level of noise suppression performance. In this paper we describe a class of adaptive directional image smoothing filters based on generalized Gaussian distributions. We propose a measure of spread for the pixel values based on the maximum likelihood estimate of a scale parameter involved in the generalized Gaussian distribution. Several experimental results indicate a significant improvement compared to some standard filters.     

Real-time directional stylization of images and videos

This paper describes a real-time non-photorealistic rendering system that automatically produces stylistic effects from photos and videos. The algorithm includes the capture of salient shapes in the image using a smooth direction field and the abstraction of both colors and shapes along the direction field. In addition to the directional stylization, the proposed algorithm has many good properties. First, the temporal coherence is preserved without any extra processing. Second, the level of abstraction can be controlled within constant time complexity. Last but not least, the parallel GPU implementation allows the real-time stylization of online videos. A variety of experimental results demonstrate the effectiveness of the system in producing high-quality abstract illustrations.     

Parallel implementation of sequential morphological filters

Many useful morphological filters are built as more or less long concatenations of erosions and dilations: openings, closings, size distributions, sequential filters, etc. An efficient implementation of these concatenations would allow all the sequentially concatenated operators run simultaneously, on the time-delayed data. A recent algorithm (see below) for the morphological dilation/erosion allows such inter-operator parallelism. This paper introduces an additional, intra-operator level of parallelism in this dilation/erosion algorithm. Realized in a dedicated hardware, for rectangular structuring elements with programmable size, such an implementation allows obtaining previously unachievable, real-time performances for these traditionally costly operators. Low latency and memory requirements are the main benefits when the performance is not deteriorated even for long concatenations or high-resolution images.     

Real-time implementation of airborne inertial-SLAM

This paper addresses some challenges to the real-time implementation of Simultaneous Localisation and Mapping (SLAM) on a UAV platform. When compared to the implementation of SLAM in 2D environments, airborne implementation imposes several difficulties in terms of computational complexity and loop closure, with high nonlinearity in both vehicle dynamics and observations. An implementation of airborne SLAM is formulated to relieve this computational complexity in both direct and indirect ways. Our implementation is based on an Extended Kalman Filter (EKF), which fuses data from an Inertial Measurement Unit (IMU) with data from a passive vision system. Real-time results from flight trials are provided.     

Real-time Java simulations of multiple interference dielectric filters

An interactive Java applet for real-time simulation and visualization of the transmittance properties of multiple interference dielectric filters is presented. The most commonly used interference filters as well as the state-of-the-art ones are embedded in this platform-independent applet which can serve research and education purposes. The Transmittance applet can be freely downloaded from the site http://cpc.cs.qub.ac.uk.

Program summary

Program title: TransmittanceCatalogue identifier: AEBQ_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBQ_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 5778No. of bytes in distributed program, including test data, etc.: 90 474Distribution format: tar.gzProgramming language: JavaComputer: Developed on PC-Pentium platformOperating system: Any Java-enabled OS. Applet was tested on Windows ME, XP, Sun Solaris, Mac OSRAM: VariableClassification: 18Nature of problem: Sophisticated wavelength selective multiple interference filters can include some tens or even hundreds of dielectric layers. The spectral response of such a stack is not obvious. On the other hand, there is a strong demand from application designers and students to get a quick insight into the properties of a given filter.Solution method: A Java applet was developed for the computation and the visualization of the transmittance of multilayer interference filters. It is simple to use and the embedded filter library can serve educational purposes. Also, its ability to handle complex structures will be appreciated as a useful research and development tool.Running time: Real-time simulations     

Finite difference implementation of distributed parameter filters

The numerical problems associated with the full three-dimensional (spatial) distributed parameter filters demand a novel technique that maintains accuracy and efficiency for the complex partial differential Riccati equation governing the filter variance. The filters can be successfully implemented by using numerical operators that can, in various ways, be factored. Use of the finite difference method having this property increases the accuracy and efficiency of the implementation.

This paper outlines a time-splitting technique for the numerical implementation of distributed parameter filters. The paper provides rationales to the square root and U-D factorizations of the distributed parameter filter by means of the time-splitting finite difference method.     

Periodic stabilization of look-ahead filters in VLSI implementation

A linear look-ahead filter is a model of digital dynamical systems and infinite impulse response filters for fast pipeline processing in very large scale integration (VLSI) implementation of the digital systems. Two essential problems to be dealt with in the design of look-ahead filters are stability and computational complexity of the filter. In this paper, a new periodic scheme is proposed to stabilize the d-step look-ahead filter and provide minimum amount of computation in digital implementation of the filter.     

Real-time visual tracking using complementary kernel support correlation filters

Despite demonstrated success of SVM based trackers,their performance remains a boosting room if carefully considering the following factors:first,the tradeoff between sampling and budgeting samples affects tracking accuracy and efficiency much;second,how to effectively fuse different types of features to learn a robust target representation plays a key role in tracking accuracy.In this paper,we propose a novel SVM based tracking method that handles the first factor with the help of the circulant structures of the samples and the second one by a multi-kernel learning mechanism.Specifically,we formulate an SVM classification model for visual tracking that incorporates two types of kernels whose matrices are circulant,fully taking advantage of the complementary traits of the color and HOG features to learn a robust target representation.Moreover,it is fortunate that the SVM model has a closed-form solution in terms of both the classifier weights and the kernel weights,and both can be efficiently computed via fast Fourier transforms(FFTs).Extensive evaluations on OTB100 and VOT2016 visual tracking benchmarks demonstrate that the proposed method achieves a favorable performance against various state-of-the-art trackers with a speed of 50 fps on a single CPU.     

Parallelized and pipelined hardware implementation of computationally expensive prediction filters

In this paper parallelization and segmentation methodologies are used to obtain a real‐time (RT) implementation of computationally expensive estimators or filters in an FPGA. First, the filter to be applied is briefly described, and afterwards its hardware structure and VHDL implementation are indicated. A comparative study is performed between the FPGA parallelized implementation and the implementation in a sequential processor. The analysis proves that the execution times measured on the FPGA are considerably lower, making that implementation valid for its use in RT systems. Moreover, several experimental results are shown for a visual servoing application in order to evidence the good performance of the proposed algorithms and implementations. Copyright © 2009 John Wiley & Sons, Ltd.     

OSNet: a neural network implementation of order statistic filters

A dedicated neural network model called OSNet which finds the kth largest element in an array of real numbers is proposed. Its overall processing time is constant irrespective of the number of elements in the array and is four times the processing time of a single neuron. Networks of this kind may be used as building blocks for hardware implementation of order statistic filters. Examples of using OSNet for implementing various order statistic filters and for sorting are shown.     

Digital filters for clustered-OFDM-based PLC systems: Design and implementation

This work aims to investigate the design and implementation of digital filters for separating clusters in a clustered-orthogonal frequency-division multiplexing scheme for power line communication systems. In this regard, we formulate the mathematical problem and present a criterion which is capable of searching for digital filters that maximizes data rate. In the following, several finite impulse response and infinite impulse response digital filters are analyzed in order to validate the proposed criterion and to verify the best one which fulfills the given constraints. Furthermore, regarding only the best digital filters obtained, a finite precision and complexity analyses are carried out by using a field-programmable gate array device. Based on numerical results, we show that finite impulse response equiripple minimum phase and infinite impulse response Chebyshev type II digital filters yield the best data rates among the chosen digital filters. Moreover, we point out that equiripple minimum phase digital filters consume more hardware resources than Chebyshev type II digital filters, although the first one deal better with the field-programmable gate array constraints when more bits are used to implement the digital filter. Due to that, finite impulse response digital filters are more indicated to be implemented in a field-programmable gate array device.     

访问权限实时更新的模型与实现

为了保证在动态环境下信息系统的安全性，需要一个良好的访问控制模型，对访问控制策略的实时变化立即作出反映，并采取必要的措施。描述了一种支持访问权限实时更新的访问控制模型和实现，并进行了并发性分析。在这种模型中，访问权限实时更新的并发控制算法简单且易于实现。在并发环境中，多个主体读写数据和修改访问控制策略并互相影响时，可直接应用该模型与算法。     

AVS全I帧视频编码器的FPGA实时实现

AVS视频编码标准是我国自主知识产权的信源编码标准。完成了AVS视频编码器在FPGA平台上的设计与实现。考虑硬件平台的结构特点,采用可重用设计和流水线设计对编码器进行优化,保证了流水线的高效运行以及硬件资源的最优利用。通过ISE软件仿真和Xilinx公司Vritex-4 pro平台验证,最高工作频率可达110 MHz,满足CIF分辨率下I帧在FPGA硬件平台的实时编码要求。     

实时动态信息发布系统实现及发展

实时动态信息发布系统正是在这种背景环境下诞生的一种新型的媒体发布应用系统。实时动态信息发布系统是一种通过数字化音、视频多媒体处理,通过网络实现远程多点分布式播放和集中管理控制的系统,播放的信息是实时动态系统;一个操作员可以集中建立、编辑和分配内容给网络环境中的数量庞大的显示终端,即实现一台服务器集中管理,向多个不同场所地点的显示终端发布实时动态的多媒体信息。     

Real-time automatic recognition of omnidirectional multiple barcodes and DSP implementation

Barcodes have been extensively adopted in daily life, such as in merchandise labels, inventory control, storage/retrieval systems and inspection. Computer-vision-based barcode recognition can definitely facilitate barcode reading, especially for multiple barcodes and free orientation and in complex scenarios. This work, presents an automatic barcode detection and recognition algorithm for multiple and rotation invariant barcode decoding. The proposed system comprises three stages. First, the barcode is extracted by coarse-to-fine segmentation in four steps: background small clutter reduction, candidate barcode segmentation, barcode verification and barcode rotation and regularization. To enhance the barcode region, thin and small background noise clusters are eliminated using Max–Min Differencing. The approach combines several image-processing schemes, namely Gaussian smoothing filtering, connected component analysis, orientation homogeneity, moment analysis and iterative thresholding. The second stage decodes the barcode by scanning multiple traversal lines, thus preventing decoding errors due to minor barcode defects. Finally, the proposed system is implemented and optimized on a DM6437 DSP EVM board. Experimental results indicate that the proposed approach can locate multiple and omnidirectional barcodes, even with a complex background and minor distortion. The recognition rates for 10,395 lottery barcodes and 388 merchandise barcodes are 99.74 and 90.7%, respectively. The proposed system is promising and has been successfully adopted in commercial applications of lottery reading and verification of winning numbers.     

基于稀疏卷积特征和相关滤波的实时视觉跟踪算法

为提高分层卷积相关滤波视觉跟踪算法的实时性能,提出一种稀疏卷积特征的实时目标跟踪算法。首先,在分析不同层卷积特征的基础上,采用等间隔采样的方式提取每个卷积层的稀疏卷积特征;然后,对每个卷积层特征的相关滤波响应值进行加权组合,得到目标预测的位置;最后,采用稀疏的模型更新策略进一步提高算法的运行速度。在OTB-2015新增的50组数据上对所提算法进行测试,实验结果表明,该算法的平均距离精度为82.2%,比原分层卷积特征跟踪算法提高了5.25个百分点,对目标姿态以及遮挡等变化具有较好的鲁棒性。该算法的平均跟踪速度为32.6帧/s,是原分层卷积特征跟踪算法的近3倍,能达到实时跟踪的效果。     

The design and implementation of multiplierless nonrecursive linear phase discrete time filters

This paper develops techniques for the design and implementation of linear phase discrete time filters that are implemented using only delays, adds and subtracts. Sometimes called discrete time linear phase transport processors, these filters have finite length integer valued impulse responses. The design technique developed in this paper determines an optimal integer valued impulse response that minimizes the mean square error in the filter's passband and stopband while bounding the impulse response values to a specified value. The implementation technique developed in this paper generates a structure that can realize integer valued impulse responses using only delays, adds and substracts.     

Design and implementation of embedded computer vision systems based on particle filters

Particle filtering methods are gradually attaining significant importance in a variety of embedded computer vision applications. For example, in smart camera systems, object tracking is a very important application and particle filter based tracking algorithms have shown promising results with robust tracking performance. However, most particle filters involve vast amount of computational complexity, thereby intensifying the challenges faced in their real-time, embedded implementation. Many of these applications share common characteristics, and the same system design can be reused by identifying and varying key system parameters and varying them appropriately. In this paper, we present a System-on-Chip (SoC) architecture involving both hardware and software components for a class of particle filters. The framework uses parameterization to enable fast and efficient reuse of the architecture with minimal re-design effort for a wide range of particle filtering applications as well as implementation platforms.     

基于定点DSP的MP3实时解码器的设计与实现

FD216是智原科技公司出品的一款结构与ADI公司的ADSP-2181相类似且指令集相兼容的高性价比16位定点DSP芯片。利用智原科技公司提供的开发工具包,可以方便地将C算法移植到FD216中。详细介绍了在FD216评估板上用嵌入式C语言和汇编语言混合编程的方法设计并实现基于定点DSP的MP3实时解码器的整个流程。