无参考图像质量评价综述

图像质量对人类视觉信息的获取影响很大, 如何在没有参考图像的情况下准确地评价失真图像的质量是一个关键但又非常困难的问题. 本文回顾了近20年来无参考图像质量评价发展的主要技术. 首先,介绍了这一领域常用的衡量评价算法性能的技术指标,以及几个网上共享的典型图像质量评价数据库; 然后,对各种无参考图像质量评价算法进行详细的分类介绍和特点评析; 最后,基于典型数据库对近几年的一些非特定失真图像质量评价方法进行了性能测试和比较. 目的是为这一领域的研究人员提供一个较为全面的、有价值的文献参考.     

姗姗而来的好戏 松下TH-58PZ700C等离子电视机

“大尺寸，就看等离子”这一松下VIERA等离子电视机的广告词非常生动地体现了等离子电视机在平板电视市场中的宣传策略。然而，面对如日中天的液晶电视不断推陈出新的性能革新及成本降低，等离子电视机越来越显得力不从心，尤其在Full HD全高清热潮来临之际,等离子电视机的生产厂商显然有些反应滞后。如今中国市场已经遍布从37英寸至70英寸以上的全高清液晶电视机型.而与此形成鲜明对比的则是等离子电视机鲜有达到1920×1080分辨率的产品（除了近乎天价的松下65英寸TH-65PV600C）。难道等离子电视机只能坐以待毙？PZ700C系列便是松下给出的最强有力的回答。[编者按]     

面向真实水下图像增强的质量评价数据集

目的 由于光在水中的衰减/散射以及微生物对光的吸收/反射等影响,水下图像通常存在色偏、模糊、光照不均匀以及对比度过低等诸多质量问题。研究人员对此提出了许多不同的水下图像增强算法。为了探究目前已有的水下图像增强算法的性能和图像质量客观评价方法是否适用于评估水下图像,本文开展大规模主观实验来对比不同水下图像增强算法在真实水下图像数据集上的性能,并对现有图像质量评价方法用于评估水下图像的准确性进行测试。方法 构建了一个真实的水下图像数据集,其中包含100幅原始水下图像以及对应的1 000幅由10种主流水下图像增强方法增强后的图像。基于成对比较的策略开展水下图像主观质量评价,进一步对主观评价得到的结果进行分析,包括一致性分析、收敛性分析以及显著性检验。最后将10种现有主流的无参考图像质量评价在本文数据集上进行测试,检验其在真实水下图像数据集上的评价性能。结果 一致性分析中,该数据集包含的主观评分有较高的肯德尔一致性系数,其值为0.41;收敛性分析中,所收集的投票数量与图像数量足够得到稳定的主观评分;表明本文构建的数据集具有良好的有效性与可靠性。此外,目前对比自然图像的无参考图像质量评价方法并不...     

聚焦平板电视技术新进展

等离子、大屏液晶、SED将共同撑起超薄平板电视的天空。从目前的情况来看,率先进入平民化阶段的等离子电视最有希望获得普及。     

基于嵌入式的人脸图像采集显示系统的制作

针对目前嵌入式开发平台上视频显示不流畅的现象,文中提出通过USB 摄像头采集人脸图像的方案。该方 案是基于三星S5PV210 处理器和嵌入式Linux 操作系统,并在其移植了Qt 和OpenCv。文章介绍了以USB 摄像头为视频图像 采集设备,通过OpenCv 进行视频图像采集的过程,以及通过Qt 实现人脸图像实时显示在LCD 屏上的过程,经测试图像能够 在LCD 屏上流畅显示,为实时在嵌入式平台上流畅显示视频图像提供了方案。     

DMA在高清数字电视中的应用及缓冲区管理

随着大规模集成电路技术的发展,高清数字电视的SoC芯片的功能日益强大,集成了各种新的图像处理技术.高清电视SoC芯片对图像帧进行处理,提高图像的整体质量.介绍了DMA在高清数字电视中缓存图像数据过程中的应用.讲解了DMA操作的基本原理,介绍了图像数据在存储器中的存储方式,以及在DMA操作中所用到缓冲区的管理流程.     

交会对接仿真电视图像TMO算法主观评价

通过对实时渲染仿真交会对接电视图像的主观评价,指出调和映射处理(TMO)算法的修正是提高仿真场景逼真度的方法.基于交会对接仿真电视图像TMO算法应用,分别针对S-curve算法、自适应对数算法和Reinhard算法设计了基于静态图像对比的亮度调和因子评价实验和基于动态场景对比的算法应用距离段评价实验,并对实验结果的均值、标准差以及HSD值进行了计算与分析;上述3种算法亮度调和因子分别为6.0,0.6和2.2,依次应用于远距离,中、近距离和靠拢距离时仿真电视图像有最佳评价和显示效果.实验结果表明,采用同种TMO算法处理的交会对接仿真图像动态场景真实感效果优于静态图像;在交会对接不同距离段内,仿真场景需要采用不同的TMO渲染方法.     

基于EZW的嵌入式图像编码算法的研究

嵌入式零树小波(EZW)编码算法是基于小波变换的一种图像压缩方法,它可以实现渐进编解码,进行有损或无损压缩,具有较高的压缩比和图像恢复质量.在研究嵌入式零树小波编码算法及原理的基础上,描述了算法的应用过程,阐述了具体的实现思路.结合多组图像数据对算法的过程进行测试,对其性能进行了评价.评价结果说明算法在原来方法的基础上进行了一些有效的改进,获得了更高的编码性能.     

等离子电视机已“死”？

2006年1～6月全球40英寸以上大屏幕电视机市场中等离子电视机的份额为47％，微显背投电视机为26％，液晶电视机仅为17％。等离子电视机产品在全球热销时，在国内市场的占有率却节节下降，甚至有了等离子电视机即将被液晶电视机“消灭”的传赢[编者按]     

基于解析稀疏表示的图像模糊无参考快速评价算法

针对模糊图像的质量评价,提出了一种基于解析稀疏表示的图像模糊快速评价算法。考虑到模糊会造成图像中高频信息的损失,因此所提出的方法通过衡量图像中的能量来评价图像的模糊程度。首先利用解析稀疏表示字典将待评价图像进行分解,并通过稀疏表示系数计算图像的能量,以作为图像模糊程度的指标。为了消除图像内容对评价结果的影响,采用图像块的方差和来对图像的能量进行归一化。然后利用视觉显著性进行加权,使得模糊质量分数与主观评价结果更加一致。最后在四个通用的图像质量数据库上对算法的性能进行测试。实验结果表明该算法的性能优于现有算法,且计算复杂度较低。     

A real-time image processor with combining dynamic contrast ratio enhancement and inverse gamma correction for PDP

Inverse gamma correction must be performed before displaying the received video signal because alternating current plasma display panel (AC PDP) has a linear output luminance response to a digital-valued input. At the same time contrast ratio enhancement is necessary for improving the image quality of display devices. The histogram equalization (HE) is an important contrast ratio enhancement method. But sometimes HE can produce unrealistic effects in images. In this paper, a new method of combining dynamic contrast ratio enhancement and inverse gamma correction for AC PDP is proposed. The dynamic contrast ratio enhancement and the inverse gamma correction are realized simultaneously in the proposed method. Furthermore the over-enhancement caused by the traditional HE can be avoided. A real-time image processor with the proposed method was designed and implemented. Simulations and experimental results on a 50-in. AC PDP show that the image quality of AC PDP can be improved obviously.     

Floating single sustain drive method for AC plasma display panel

This paper presents a method for driving an AC plasma display panel (PDP). This method separates the circuit ground for the sustain pulse generator from the system ground during the sustain period, so it is named the floating single sustain method. The problems observed in previous single sustain methods are solved by separating the ground systems. A drive waveform and circuit for the floating single sustain method are proposed, and a cost-effective method of connecting the drive circuit to the electrodes of a PDP is presented. Experimental results on a 42-in. WVGA single-scan PDP show that the proposed waveform and circuit are well suited for driving the PDP; all problems observed in the previous single sustain method are solved and the power consumption due to the sustain power leakage to the data drive circuit is eliminated.     

Testing of PolPA-based usage control systems

The implementation of an authorization system is a critical and error-prone activity that requires a careful verification and testing process. As a matter of fact, errors in the authorization system code could grant accesses that should instead be denied, thus jeopardizing the security of the protected system. In this paper, we address the testing of the implementation of the Policy Decision Point (PDP) within the PolPA authorization system that enables history-based and usage-based control of accesses. Accordingly, we propose two testing strategies specifically conceived for validating the history-based access control and the usage control functionalities of the PolPA PDP. The former is based on a fault model able to highlight the problems and vulnerabilities that could occur during the PDP implementation. The latter combines the standard technique for conditions coverage with a methodology for simulating the continuous control of the PDP during the runtime execution. Both strategies are implemented within a testing framework supporting the automatic generation and execution of security test suites. Results produced by the application of this testing framework to a real case study are presented.     

New metacode coding concept for improving PDP gray‐scale quality

Abstract— Today, methods for power management of plasma display panels (PDP) have been developed in order to provide a maximum peak white for a given picture content with stable power consumption. However, the quality of the gray‐scale portrayal with such concepts is far from the actual CRT standards. We have developed a new PDP encoding concept called Metacode to improve gray‐scale quality during all power and contrast adjustment towards CRT level.     

Equivalent circuit model and characteristic parameters for AC PDP discharge cells

In this paper, an equivalent circuit model for discharge cells of alternating current plasma display panel (AC PDP) is developed. In this model, a voltage controlled switch is introduced to describe the breakdown process of the gas discharge. And two zener diodes are introduced to describe the sustain process of the gas discharge. Three internal discharge characteristic parameters, the breakdown voltage of discharge gap, the minimum sustain voltage of discharge gap and the discharge cell capacitance ratio, are proposed. The formulas for expressing external discharge characteristic parameters by internal discharge characteristic parameters are derived. The experimental method for measuring internal characteristic parameters is developed and the measurement results for a macro discharge cell are presented.     

A reduction method of dynamic false contour utilizing the frame‐rate‐control method with suppression of the side effect on PDPs

Abstract— The plasma‐display panel (PDP) is a type of flat‐panel display that can display a high‐quality image. However, when moving images are displayed, annoying disturbances such as false contour noise occurs. This noise is called dynamic false contour (DFC). To achieve a higher‐quality image, DFC has to be reduced. Therefore, a new method to reduce DFC is proposed. To find a way to reduce DFC, a new evaluation value for it has been defined: the evaluation value of dynamic false contour (EVDFC). This value is defined on the basis of a person's subjective evaluation. By applying this value, the cause that generates DFC can be identified. On the basis of these studies, a new method for reducing DFC by applying frame‐rate control (FRC) with suppression of the side effect is proposed. This improved method can be used to provide high‐quality images.     

移动应用众包测试质量影响因素分析

针对移动应用众包测试质量影响因素复杂多样致使测试质量难以评估的问题，提出一种基于皮斯尔曼相关系数分析的质量影响因素分析方法。首先，通过对测试平台、任务、人员三方面的分析获取潜在质量影响因素；然后，利用斯皮尔曼相关系数分析法计算潜在因素与测试质量的关联程度并筛选出强关联因素；最后，通过多元逐步回归法建立强关联因素与测试质量间的线性评价关系。实验结果表明，与传统专家人工评价方式相比，所提方法在面向大量测试任务质量评价时，能够保持更小的评价误差波动，可以准确地筛选出移动应用众包测试质量关键影响因素。     

A virtual pixel technique for doubling the PDP resolution of moving images

A virtual pixel technique increases the resolution of spatially discrete pixilated display devices when the eye moves relative to the screen. By using this technique, an effective PDP resolution can be doubled for moving images. For instance, 1280‐horizontal‐pixel data can be displayed on a VGA PDP having only 640 horizontal pixels. The positions and sizes of the virtual pixels are controlled by choosing light‐emission timings and durations of the actual pixels as their images move across the retina.     

移动云计算环境中基于代理的可验证数据存储方案

现有云计算可验证数据存储协议无法直接应用于终端存储和计算能力有限的移动计算环境。针对该问题,提出移动计算环境下基于代理的可验证云存储协议,在终端和云服务器之间引入一个半可信的安全计算代理,利用代理来帮助移动终端用户完成计算密集的操作,从而使得可验证数据存储方案可用于移动计算环境。提出一个具体的可验证数据存储协议,形式化证明了所提协议满足随机预言机模型下的选择明文攻击(CPA)安全,量化分析结果表明协议设计适用于移动计算环境,符合设计目标。     

基于灰色理论的软件测试质量评价方法

针对软件测试质量如何评价的问题,指出软件测试适合灰色理论应用,根据软件测试一般过程建立了软件测试质量模型,提出了基于灰色关联分析的软件测试质量评价方法.结果表明:该方法理论上先进,技术上可行,评价结果客观,为解决软件测试质量评价提供了一种新方法.