BIST for D/A and A/D converters

The expense of specialized equipment can be a problem in testing high resolution D/A converters. A BIST alternative that tests offset voltage, integral nonlinearity, differential nonlinearity, and gain error without such equipment or the use of a digital signal processor or microcontroller shows promise. We also extend the same technique to test a wide range of A/D converters     

3D and 2D/3D holograms model

The estimating problem of 3D holograms orientation selectivity on angular, orthogonal, and azimuthal sensitivity parameters is formulated and solved. Tenfold increase of density 3D, 2D/3D holograms in comparison with 2D holograms at given selectivity for ones is shown in theory and experimentally.     

Hierarchical Representations of 2D/3D Gray-Scale Images and Their 2D/3D Two-Way Conversion

This article proposes G-octree as an extension of G-quadtree to three dimensions. A G-octree reflects in its construction a hierarchy of gray-scale level value homogeneity, as well as a hierarchy of spatial resolution. The article also develops two-way G-quadtree/Goctree conversion procedures based on the algorithms for the binary case. These procedures provide an integrated processing environment for hierarchically represented 2D/3D gray.scale images. We demonstrate our approach with an application to the color coding of macro-autoradiography images taken from rat brains.     

用C语言编写的模/数与数/模转换程序

在计算机实时控制和处理系统中 ,计算机需要对模拟信号进行采样 ,转换为数字量进行处理 ,然后再根据处理后的结果进行输出控制 ,这就是模 /数与数 /模转换。目前在《微型计算机控制技术》、《微型计算机接口技术原理及应用》等教材中 ,程序的编制均是采用汇编语言进行的。由于汇编语言属于低级语言 ,在数据显示和人机对话方面的编程较为复杂 ,而Ｃ语言既具有低级语言的特点 ,又具有高级语言的优点 ,能克服汇编语言在此方面的不足。下面介绍两个用Ｔｕｒ ｂｏＣ编写的模 /数与数 /模转换的程序。程序均在 386微机上调试通过 ,实验所用的设备…     

用A/D、D/A转换实现模拟信号可编程放大与延时

在信号处理过程中,常需要对信号进行放大和对放大倍数进行调整,有时还需要对信号进行定量的延时,本文用A/D、D/A转换的方法对信号进行放大倍数的调整,以及实现信号的可编程延时.     

用低位D／A转换器实现高位D／A转换

本文介绍一种采用低位Ｄ／Ａ转换器实现高位Ｄ／Ａ转换的方法，并对其分辨率及误差进行了推导。     

基于DSP的定时器在模数和数模转换中的应用

采用计算定时器周期寄存器值的方法设置TMS320C6713 DSP定时器,以精确控制D/A数模转换输出信号的频率或A/D模数转换的采样频率,结合C6713 DSP定时器寄存器和配置定时器的一般步骤,以及中断寄存器和可屏蔽中断发生满足的条件,编写了用两个定时器分别控制D/A和A/D的中断初始化程序,并在C6713 DSP硬件平台上进行了验证;结果表明:计算定时器周期寄存器值的方法正确,能够产生指定频率的信号或以指定频率对信号进行采样,控制方式灵活并且精度较高。     

一种抗D/A和A/D变换的音频水印算法

音频水印的许多应用要求水印能在模拟环境中保留下来，这涉及到水印的D／A和A／D（以下简称DA／AD）变换，然而，音频水印抗DA／AD变换尚末引起人们的充分重视，已有的音频水印算法能抵抗DA／AD的很少，文中通过大量的实验，分析并得出了在DA／AL）过程中影响音频水印的主要因素：波形失真和时间轴线性伸缩，并针对这些因素提出了一个基于DWT的抗DA／AD变换的茸音频水印算法，针对音频水印DA／AD变换过程中时间轴上的线性伸缩和因幅值变化与噪声影响产生的波形失真，作者在算法中分别采取了相应的对策：（1）在检测过程中结合同步码蕈定位和线性伸缩恢复来消除时间轴上线性伸缩带来的影响；（2）针对幅值改变，在DWT域采用了基于三段低频小波系数之间能量关系的嵌人对策；（3）自适应调整嵌入强度来满足抗噪声攻击的要求，实验表明，所提出的音频水印算法具有很强的抗DA／AD攻击性能和抗其它各种通用的音频处理和攻击的能力。     

Switching directional BLUs for full‐resolution auto‐stereoscopic 3D/2D and 2D/3D LCDs

Directional backlight unit (BLU) design concept was applied to realize full‐resolution field alternate auto‐stereoscopic liquid crystal displays (LCDs) with built‐in 3D/2D and 2D/3D. The application‐oriented BLU design requires priority in realizing 2D mode or 3D mode. The switching characteristic of BLU with two confronting illuminating sets was applied to build 2D mode into 3D display and 3D mode into 2D display. An LCD with 2D mode as primary function requires higher double‐sided luminance uniformity than 3D mode. On the other hand, an LCD with 3D mode requires higher single‐sided luminance uniformity than 2D mode. For increasing the double‐sided luminance uniformity for 2D mode as a primary function of the display, the former BLU design was realized by using uniform prismatic structure, that is, using uniform bilateral prismatic structure with a cross section of isosceles triangle on the back surface of the light‐guide plate. For increasing single‐sided luminance uniformity for 3D mode as a primary function of the display, the latter was realized by using graded angle design, that is, unilateral prisms with a cross section of a scalene triangle on the back surface of the light‐guide plate. The LCDs of small‐sized‐handheld game devices and still cameras were fabricated using the 3D/2D and 2D/3D displays.     

2D/3D image registration using regression learning

In computer vision and image analysis, image registration between 2D projections and a 3D image that achieves high accuracy and near real-time computation is challenging. In this paper, we propose a novel method that can rapidly detect an object’s 3D rigid motion or deformation from a 2D projection image or a small set thereof. The method is called CLARET (Correction via Limited-Angle Residues in External Beam Therapy) and consists of two stages: registration preceded by shape space and regression learning. In the registration stage, linear operators are used to iteratively estimate the motion/deformation parameters based on the current intensity residue between the target projection(s) and the digitally reconstructed radiograph(s) (DRRs) of the estimated 3D image. The method determines the linear operators via a two-step learning process. First, it builds a low-order parametric model of the image region’s motion/deformation shape space from its prior 3D images. Second, using learning-time samples produced from the 3D images, it formulates the relationships between the model parameters and the co-varying 2D projection intensity residues by multi-scale linear regressions. The calculated multi-scale regression matrices yield the coarse-to-fine linear operators used in estimating the model parameters from the 2D projection intensity residues in the registration. The method’s application to Image-guided Radiation Therapy (IGRT) requires only a few seconds and yields good results in localizing a tumor under rigid motion in the head and neck and under respiratory deformation in the lung, using one treatment-time imaging 2D projection or a small set thereof.     

A 2D/3D model-based object tracking framework

This paper presents a robust framework for tracking complex objects in video sequences. Multiple hypothesis tracking (MHT) algorithm reported in (IEEE Trans. Pattern Anal. Mach. Intell. 18(2) (1996)) is modified to accommodate a high level representations (2D edge map, 3D models) of objects for tracking. The framework exploits the advantages of MHT algorithm which is capable of resolving data association/uncertainty and integrates it with object matching techniques to provide a robust behavior while tracking complex objects. To track objects in 2D, a 4D feature is used to represent edge/line segments and are tracked using MHT. In many practical applications 3D models provide more information about the object's pose (i.e., rotation information in the transformation space) which cannot be recovered using 2D edge information. Hence, a 3D model-based object tracking algorithm is also presented. A probabilistic Hausdorff image matching algorithm is incorporated into the framework in order to determine the geometric transformation that best maps the model features onto their corresponding ones in the image plane. 3D model of the object is used to constrain the tracker to operate in a consistent manner. Experimental results on real and synthetic image sequences are presented to demonstrate the efficacy of the proposed framework.     

2D/3D Isometric Transformation Using Spring-Mass System

２Ｄ／３ＤＩｓｏｍｅｔｒｉｃＴｒａｎｓｆｏｒｍａｔｉｏｎＵｓｉｎｇＳｐｒｉｎｇ＿ＭａｓＳｙｓｔｅｍＦａｎＪｉｎ１ＭａｔｈｅｗＭ．Ｆ．Ｙｕｅｎ２ＱｉｆｕＷａｎｇ１ＺｈｏｕＪｉ１１ＴｈｅＣＡＤＣｅｎｔｅｒｏｆＴｈｅＨｕａｚｈｏｎｇＵｎｖｉｅｒｓｉｔｙｏｆ...     

2D/3D image registration on the GPU

We present a method that performs a rigid 2D/3D image registration efficiently on the Graphical Processing Unit (GPU). As one main contribution of this paper, we propose an efficient method for generating realistic DRRs that are visually similar to x-ray images. Therefore, we model some of the electronic post-processes of current x-ray C-arm-systems. As another main contribution, the GPU is used to compute eight intensity-based similarity measures between the DRR and the x-ray image in parallel. A combination of these eight similarity measures is used as a new similarity measure for the optimization. We evaluated the performance and the precision of our 2D/3D image registration algorithm using two phantom models. Compared to a CPU + GPU algorithm, which calculates the similarity measures on the CPU, our GPU algorithm is between three and six times faster. In contrast to single similarity measures, our new similarity measure achieved precise and robust registration results for both phantom models.     

Reactive 2D/3D garment pattern design modification

This paper presents a new 3D garment simulation result update algorithm for the 2D garment pattern design modification. The proposed algorithm enables the 3D garment fitting simulation result directly to react to the modification in the 2D patterns. The algorithm performs a topological invariant deformation of the 2D pattern mesh after the boundary of the 2D pattern undergoes a topological consistent modification. The length of each of the edges in the mesh defined as the equilibrium state parameter is updated and then directly used in the 3D garment fitting simulation to update the original simulation result. The advantage of the proposed algorithm is that the mesh topology of the 2D garment pattern is preserved and thus simplifies the numerical scheme by maintaining the consistency of the matrix equation. With this approach, the 3D garment fitting simulation does not need to repeat the entire simulation for every modification and can react to the 2D pattern modification efficiently and speedily.     

基于弹簧质点模型的二维/三维映射算法*

提出了一种用于服装设计的二维/三维映射算法.该算法基于弹簧质点变形模型,服装裁剪片二维到三维映射及三维到二维映射可以在该模型中得到统一的实现.在服装裁剪片二维到三维的映射过程中,二维裁剪片被放置在人体模型附近的初始位置,在缝合力的作用下,裁剪片自动变形并缝合到人体模型上.在服装裁剪片三维到二维映射的过程中,三维裁剪片被初始映射到指定的平面内,在弹性变形力的作用下,逐步变形并得到最终的二维裁剪片.在进行服装裁剪片二维到三维映射的过程中,考虑了干涉检验的问题.     

一种具有RST不变性的2D/3D轨迹相似性度量

具有旋转、缩放、平移不变性的轨迹相似性度量是实现精准手语识别、相似轨迹检索等的关键环节,常规的相似性度量往往不满足这一要求,特别是不具备旋转不变性。提出一种具有旋转、缩放、平移不变性的轨迹相似性度量方法,该方法首先对轨迹进行滤波、归一化、等间距重采样等预处理操作,然后对任意两条待比较的轨迹估计最优旋转矩阵,从而消除旋转对距离度量的干扰。该方法对二维、三维轨迹数据均适用,计算复杂度为[ON],与曲率、挠率等不变量相比,该方法对轨迹噪声不敏感。     

用DAQ卡实现A/D与D/A转换的同步进行

随着计算机技术和电子电工测量技术的发展 ,在测控系统中使用PC进行信号测试和分析成为一个新的发展方向 ,由此产生了一种新型测量仪器———虚拟测量仪器。所谓虚拟测量仪器就是以微机为测量平台 ,用虚拟仪器软件模拟实际仪器操作界面 ,通过人机交互完成对信号的采集、调理、分析处理和结果显示输出等功能。实现虚拟测量仪器的关键 ,一个是硬件数据采集设备 ,完成现场信号的采集、调理和缓存 ;另一个就是对数据进行分析处理并模拟仪器仪表面板的软件。本项目采用了VisualC + +来编制虚拟系统应用程序 ,采集卡的驱动程序用Windows环境下动…     

VC++中利用DLL技术实现A/D和D/A转换

DLL编程在软件开发中发挥着重要的作用,程序中使用DLL有显著的优点。在编写三容系统的控制程序时,为了实现数据采集和控制信号输出,用DLL技术实现了A/D和D/A转换,控制程序达到了很好的控制效果。同时介绍了DLL的使用和编程方法,并给出了示例代码。