一种投影显示图像颜色失真校正方法

颜色校正是提高投影显示图像视觉效果及内容感知理解程度的重要环节,针对此,提出了一种基于颜色空间变换和亮度响应函数(ITF)的颜色校正方法。设计一幅16×16的灰度渐变棋盘格作为标定图像,进行采样;利用测光表测量环境光,以调整相机拍摄参数;根据投影仪-相机系统映射关系矩阵,求解匹配采样点对;建立亮度响应曲线的经验参数模型,利用最小二乘法估计曲线参数;依据亮度响应曲线的反函数建立颜色查找表,从而实现投影显示图像的颜色失真校正。在LCD投影仪上进行了该算法的可行性和效果测试,实验结果表明:该算法校正后的投影画面质量较好,且实现简单。     

多投影仪组合显示的自反馈亮度校正

针对目前的亮度校正方法存在的问题,提出了闭环的自反馈亮度校正方法。该方法首先计算一个初始模板;然后在反馈过程中,使用模板对白色图像进行亮度衰减,根据相机获取的投影图像,以及屏幕与投影仪坐标的对应关系,用一定的模板修正规则来修正每个投影仪对应的亮度校正模板;重复反馈过程,直到达到亮度一致的约束条件。该方法避免了亮度响应曲线的复杂又耗时的测量工作,通过迭代反馈来不断修正亮度校正模板,最终使得亮度校正后的图像投影后逼近亮度一致。自反馈亮度校正方法中计算的初始亮度校正模板过渡更均匀,消除了模板中的三角带问题;采用的模板更新方法能够使迭代反馈过程更快地收敛。实验证明,该方法能够有效地解决自由立体投影显示系统中的亮度校正问题。     

DE-GMAW焊接系统的非线性建模及参数估计

为了更好地研究和控制可消耗的双电极熔化极气体保护电弧焊接系统(DE-GMAW),针对该系统建立了一个多输入多输出(MIMO)的非线性模型,并采用递推最小二乘法原理对模型参数进行了估计.阶跃信号下交叉验证结果表明,所得模型很好的反映了其系统特性,可以用来进行控制系统的设计与系统本身的分析理解.     

多投影仪自由立体显示的GPU几何及亮度校正技术

由多个投影仪拼接显示的自由立体显示系统有很大的显示区域,能够产生更好的立体显示效果.针对可伸缩高分辨率多投影仪自由立体显示的系统特性和屏幕特性,通过分析各种几何校正和亮度校正算法,采用二次几何校正方法解决了自由立体显示中斜投影造成的部分特征点不在屏幕上的问题;提出了基于GPU的亮度自适应多模板校正方法,并通过GPU程序...     

改进的非线性系统最小二乘算法

本文给出了可以统一处理线性系统，非线性系统参数辨识的改进最小二乘算法，包括批量形式及递推形式，它是文１，２中算法的综合及推广，改进了收敛速度，能克服病态，算法简单，易于应用，并且给出了算法的收敛性证明。     

非线性系统最小二乘估计的目标补偿算法

本文提出了求解非线性系统最小二乘估计问题的一种新的分解协调方法,该方法通过对各子问题的目标直接引入适当的补偿项进行协调,具有协调计算简单,子问题仍为最小二乘形式等优点,文中对该方法收敛性进行了较为详细的研究,仿真和实际应用表明,它的收敛速度快,优于整体算法和目标协调法。     

数学模型在测温系统中的应用

利用数值分析中的最小二乘法,采用n次(6次)多项式拟合出温度传感器的温度(t)与电阻(R)的代数关系。由于采用n次拟合,可以使系统温度的测量误差降低到0.2℃以下,达到许多实际场合的要求。系统采用FPGA芯片为控制核心,用硬件描述语言(VHDL)实现编码算法,以TSC传感器作为温度传感器,ADC0809作为模数转换器件,用LCD和数码管同时显示当前的实时温度。     

一类非线性随机系统的自适应控制

本文在文献「１，２」的基础上，对一类仿射非线性随机系统的最小二乘（ＬＳ）自适应控制问题进行了分析，给出了稳定性及收敛速度结果，在这里，我们仅要求非线性函数具有线性增长速度，而无需任何其它结构假设。     

多雷达组网系统空间误差分布 与配准算法仿真

空间配准是多目标跟踪系统中的关键环节.本文针对实际的多雷达组网系统,详细分析了造成观测误差的空间误差源分布情况,并对误差进行了分类.在此基础上,深入研究了各类误差配准算法,结合工程实际,推导了基于测地坐标系的目标航迹转换方程;利用最小二乘配准算法推导了广义最小二乘算法,仿真结果表明了算法的有效性.但当量测噪声相对系统偏差较大时,估计结果会变差,因而减小初始校准误差是提高系统观测精度的最重要环节.     

非线性偏最小二乘建模方法及在近红外光谱建模上的应用

偏最小二乘算法(PLS)是常用的线性光谱建模方法。针对汽油在线调合中具有非线性特点的辛烷值、干点等属性应用PLS方法建立模型误差较大问题,本文提出了残差-递阶偏最小二乘的建模方法,该方法对已经提取成分后的自变量中剩余的信息再提取主成分,并将该主成分作为新的自变量参与回归建模。仿真验证结果表明:残差-递阶偏最小二乘方法建立的模型中验证集的样本数据误差均在正负0.2之间。残差-递阶偏最小二乘方法与偏最小二乘、递阶偏最小二乘叫-PLS)两种方法比较,残差-递阶偏最小二乘建立的模型有的更高的精度和模型适应性。     

The advantage of positive text-background polarity is due to high display luminance

Reading text from computer screens is better when text is printed in dark letters on light background (positive polarity) than when it is printed in light letters on dark background (negative polarity). An experiment is presented that tests whether this positive polarity advantage is due to the fact that overall display luminance is typically higher for positive than for negative polarity displays. To this end, text-background polarity and display luminance were manipulated independently. No positive polarity advantage was observed when overall display luminance of positive and negative polarity displays was equivalent. There was only an effect of display luminance, with better performance for the higher-luminance displays. This suggests that the positive polarity advantage is in fact due to the typically higher luminance of positive polarity displays. Readability of text presented on computer screens (e.g. on websites) is better when the overall display luminance level is high, as in positive polarity displays (dark letters on light background). Display polarity per se does not affect readability.     

分镜式亮度色度传感器光学系统研究

传统的彩色亮度计一般采用光探测器结合马达旋转三色滤色片构成色度传感器;本文提出的分镜式亮度传感光学系统,采用了分镜式三色分离成像结构,使由红绿蓝滤光片组获得的三色信号和探测器直接组合形成色度传感器,由于减少了运动部件,因此改善了仪器可靠性、稳定性,降低了系统功耗。     

Improvement of luminance and luminous efficacy in PDPs

Abstract— The dependence of PDP luminance and efficacy on the input power was investigated for several Xe‐Ne gas mixtures. The input power was varied in two ways: namely, by changing the dielectric‐layer capacitance (thickness) and by changing the sustain voltage. A distinctly different behavior was found; for increasing capacitance the efficacy decreases markedly, whereas for increasing sustain voltage the efficacy increases. A design window comprising the combination of a high Xe concentration and a high sustain voltage was suggested. In this window, a high luminance and a high efficacy are concurrent. A 4‐in. test panel with 10% Xe in Ne has been realized showing a white luminance of 2040 cd/m² and an efficacy of 2.3 lm/W for continuous sustaining at 50 kHz with a sustain voltage of 225 V.     

Effects of spatial luminance nonuniformities on visual-task performance and subjective uniformity

The objectives of the experiment described in the paper were the determination of the effects of nonuniformities on operator performance and perception, and the validation of current recommended standards. Subjects performed two tasks in the presence of nonuniformities: an objective visual search task, and a subjective magnitude-estimation task for the determination of perceived uniformity. The results indicated that the nonuniformities did not appreciably affect search performance, and that current recommendations are appropriate, although the magnitude-estimation task results indicated that the subjects were sensitive to the nonuniformities. The subjective impressions of perceived uniformity results follow the contrast threshold function of the visual system.     

Visual ergonomics of video-display-terminal workstations: Field measurements of luminance for various display settings

Electronic visual displays have shown a rapid technological evolution in the last two decades. With reference to the ergonomic requirements for video display terminal (VDT) workstations (ISO 9241), at an international level, attention is focused on the human–system interaction. With reference to visual ergonomics, the aim of this study is to assess luminance conditions through in-field measurements in order to evaluate: luminance and contrast ratios, luminance and contrast non-uniformities. The assessment was applied to widespread flat screen displays and repeated for fourteen combinations of Contrast–Brightness. The analysis carried out by the Authors shows the importance of realizing a simple and quick procedure to determine the performance levels of displays used in VDT workstations. The proposed assessment could be used as a practical tool for staff assigned to assess the risks arising from VDT use in the workplace within the Occupational Health and Safety Assessment Procedure.     

视频监控系统中的非线性校正算法

在基于数字图像处理技术的视频监控系统中,车辆信息和道路信息是最为重要的参数,但由于摄像机内外参数的不同将导致图像不同程度的非线性失真,影响正确的交通参数的获得和交通现象的正确判断。基于图像网格的非线性校正算法对此能进行有效的校正,为交通视频监控提供较为准确的信息参数。实验结果表明该算法有较高的精度,并在视频监控系统中有较好地应用。     

The design and optimization of lens array for LED backlight in LCD imaging engine of helmet‐mounted display

The light‐emitting diode has become the mainstream lightsource for backlight in the liquid crystal display imaging engine of helmet‐mounted display. The paper proposes a secondary‐optics‐based design to increase the luminance and obtain a uniform illumination. Based on a point lightsource, a single double‐freeform‐surface lens is firstly designed. Then an optimization is performed according to the theory of edge‐ray to improve the uniformity for planar source. As a result, the uniformity reaches 83.4% in a circular illumination with a diameter of 8 mm. Then the lens is cut and four rectangular lenses are combined to form a lens array. But the combination leads to a non‐uniformity. So a method of optimizing the light energy distribution on the target surface is proposed. Finally, the designed lens array is manufactured. The practical measurement results show that the luminance increases by 96.4% compared with the traditional backlight and that the non‐uniformity slightly decreases by 0.86%. The lens array designed in this paper presents high practicability for applications in helmet‐mounted display.     

Applications of Level 2 BLAS in the NAG library

We describe work done to improve the performance of NAG Library routines for nonlinear equations and nonlinear least squares problems on vector-processing machines. Calls to the Level 2 BLAS routines for matrix-vector operations were introduced wherever possible, so that further efforts to tune the code could be concentrated within the Level 2 BLAS, and advantage can be taken of optimized implementations of the Level 2 BLAS when they become available. Performance measurements from a CRAY-1S, an AMDAHL VP1100, and a CDC CYBER 205 are presented to illustrate the effectiveness of this strategy.     

Survey of actual viewing conditions at home and appropriate luminance of LCD‐TV screens

Abstract— To understand actual viewing conditions at home is important for TV design. And the preferred luminance level of LCD TVs under actual viewing conditions is also important in order to obtain both good picture quality and low power consumption. The actual viewing conditions of households and the preferred luminance levels was investigated. In a field test of 83 households, the display luminance, screen illuminance, and viewing locations were measured on site. In laboratory experiments, young and elderly subjects adjusted the luminance of an LCD‐TV screen to their preferred levels under different screen illuminance levels, angular screen sizes, and average luminance levels (ALL) of the images. As a result, two equations, which represent the preferred luminance level of LCD‐TV screens corresponding to different viewing conditions for young and elderly subjects were obtained. When the ALL of the images was 25% and the screen illuminance and angular screen size were set at 100 lx and 20°, respectively, the preferred luminance was 1 60 cd/m² for the young subjects and 248 cd/m² for the elderly subjects. By using the setting of the preferred luminance of an LCD TV under actual viewing conditions, it is possible to conserve energy consumption.     

非线性系统辨识的改进双对角化最小二乘算法

本文提出了一种新的有效的非线性系统最小二乘辨识算法－－改进的双对角化最小二乘（ＭＢＬＳ）算法，在存在舍入误差的条件下，给出了算法的收敛性证明，事实上，算法的收敛性几何不受舍入误差的影响，算法是大范围数值稳定的，仿真结果说明了新算法的有效性。