Radial Basis Approximations Based BEMD for Enhancement of Non-Uniform Illumination Images

An image can be degraded due to many environmental factors like foggy or hazy weather,low light conditions,extra light conditions etc.Image captured under the poor light conditions is generally known as non-uniform illumination image.Non-uniform illumination hides some important information present in an image during the image capture Also,it degrades the visual quality of image which generates the need for enhancement of such images.Various techniques have been present in literature for the enhancement of such type of images.In this paper,a novel architecture has been proposed for enhancement of poor illumination images which uses radial basis approximations based BEMD(Bi-dimensional Empirical Mode Decomposition).The enhancement algorithm is applied on intensity and saturation components of image.Firstly,intensity component has been decomposed into various bi-dimensional intrinsic mode function and residue by using sifting algorithm.Secondly,some linear transformations techniques have been applied on various bidimensional intrinsic modes obtained and residue and further on joining the transformed modes with residue,enhanced intensity component is obtained.Saturation part of an image is then enhanced in accordance to the enhanced intensity component.Final enhanced image can be obtained by joining the hue,enhanced intensity and enhanced saturation parts of the given image.The proposed algorithm will not only give the visual pleasant image but maintains the naturalness of image also.

多尺度域视频监控图像光照分量智能校正方法

针对视频监控图像中存在的清晰度不足和光照不均匀等问题,提出了多尺度域视频监控图像光照分量智能校正方法。应用背景差分法与差值图二值化法对视频监控图像进行预处理,以减少噪声干扰。通过融合TH变换和BH变换来加强图像多尺度细节特征;利用控制因子控制锐化强度,以凸显细节特征,避免出现图像伪影情况。对图像光照分量进行自适应调节,利用二维伽马函数计算画面亮度平均值,以防止出现过度校正的情况,从而实现智能校正。测试结果表明,采用该方法校正的图像更清晰,画面光照分量均匀,图像失真较少,视觉效果较好。

Real-time Audio &Video Transmission System Based on Visible Light Communication

With the increasing popularity of solid sate lighting devices, Visible Light Communication (VLC) is globally recognized as an advanced and promising technology to realize short-range, high speed as well as large capacity wireless data transmission. In this paper, we propose a prototype of real-time audio and video broadcast system using inexpensive commercially available light emitting diode (LED) lamps. Experimental results show that real-time high quality audio and video with the maximum distance of 3 m can be achieved through proper layout of LED sources and improvement of concentration effects. Lighting model within room environment is designed and simulated which indicates close relationship between layout of light sources and distribution of illuminance.

PRNU Extraction from Stabilized Video:A Patch Maybe Better than a Bunch

This paper presents an algorithm to solve the problem of Photo-Response Non-Uniformity(PRNU)noise facing stabilized video.The stabilized video undergoes in-camera processing like rolling shutter correction.Thus,misalignment exists between the PRNU noises in the adjacent frames owing to the global and local frame registration performed by the in-camera processing.The misalignment makes the reference PRNU noise and the test PRNU noise unable to extract and match accurately.We design a computing method of maximum likelihood estimation algorithm for extracting the PRNU noise from stabilized video frames.Besides,unlike most prior arts tending to match the PRNU noise in whole frame,we propose a new patch-based matching strategy,aiming at reducing the influence from misalignment of frame the PRNU noise.After extracting the reference PRNU noise and the test PRNU noise,this paper adopts the reference and the test PRNU overlapping patch-based matching.It is different from the traditional matching method.This paper conducts different experiments on 224 stabilized videos taken by 13 smartphones in the VISION database.The area under curve of the algorithm proposed in this paper is 0.841,which is significantly higher than 0.805 of the whole frame matching in the traditional algorithm.Experimental results show good performance and effectiveness the proposed strategy by comparing with the prior arts.

煤矿掘进工作面低照度视频增强技术研究

针对煤矿掘进工作面视频光照较低、亮度不均、纹理模糊、噪声较多等问题,提出一种煤矿掘进工作面低照度视频增强算法。首先,利用卷积的可分离性将视频图像进行一维水平卷积与垂直卷积,再利用完美反射法实现视频图像自动白平衡,并使用图像混合增强技术提高视频图像整体亮度。然后,基于大气散射模型与暗通道先验方法,通过递归分割将图像分割为高光区、中间调和暗调区,并求取对应区间通道像素最大值,将其3者均值作为大气光照估计值,引入调节因子对透射率进行调整优化,并使用拉普拉斯锐化操作,增加图像高频成分、抑制图像低频成分,提高图像对比度。最后,基于改进的大气散射模型对掘进工作面低照度视频进行去雾处理。实验结果表明,视频增强算法能够对煤矿掘进工作面低照度视频进行实时增强、去雾处理,避免了视频图像暗淡、失真、模糊和突变等问题。相较于Retinex算法、ALTM算法和暗通道先验算法,视频增强算法大幅度提高了视频图像的信息熵、标准差和平均梯度,且具有较好的实时处理速度,能够为掘进工作面视频的目标识别、目标跟踪、目标监测和图像分割等后续处理提供优质、可靠的支撑。

一种矿用本安型音视频记录仪

设计了一种矿用本安型音视频记录仪。设备基于5G SOC处理器,采用感光传感器+白光/红外激光补光+本质安全电路方案,在低照度、全黑或密闭空间的环境下,能采集、压缩、存储、显示4K高清视频图像,同时将采集的音视频数据进行实时远传;记录仪具有低照度环境下成像质量高、拍摄距离远、功耗小等特点,支持TCP/IP、UDP、RTP、ONVIF、GB28181等协议,除了作为井下信息记录外,还可以辅助应急指挥部及时展开救援行动。测试结果表明:记录仪黑暗环境下图片分辨率为10688×6012,视频分辨率为2560×1440,可视距离达20 m,数据丢包率约为0.068%,时延约为15.85 ms,可实现持续视频摄录9 h或持续视频回传4 h。

基于亮度融合的低照度视频弱变化检测算法

低照度视频图像弱变化检测算法可提升安防工作的可靠性,有利于安防人员快速处理存在的风险。提出一种基于亮度融合的弱变化检测算法。对视频的每一帧图像,首先提取图像不同空间的亮度分量,设计一种亮度融合的策略,对亮度分量进行融合。将融合后的亮度分量进行形态学重建,克服噪声影响。然后使用自适应的对数比对融合后的亮度分量进行处理得到差异图,对差异图使用迭代的全变分去噪,进一步克服残余噪声。最后对差异图使用二阶段聚类方法,进一步提升变化检测精度。实验结果表明,提出算法的平均检测精度为0.770,误差为31个像素点,与对比算法相比,提升了20%以上的精确度;平均运行时间为0.16 s,时间短于对比算法2倍以上。

Static Scene Illumination Estimation from Videos with Applications

We present a system that automatically recovers scene geometry and illumination from a video, providing a basis for various applications. Previous image based illumination estimation methods require either user interaction or external information in the form of a database. We adopt structure-from-motion and multi-view stereo for initial scene reconstruction, and then estimate an environment map represented by spherical harmonics （as these perform better than other bases）. We also demonstrate several video editing applications that exploit the recovered geometry and illumination, including object insertion （e.g., for augmented reality）, shadow detection, and video relighting.

Low and non-uniform illumination color image enhancement using weighted guided image filtering

In the state of the art,grayscale image enhancement algorithms are typically adopted for enhancement of RGB color images captured with low or non-uniform illumination.As these methods are applied to each RGB channel independently,imbalanced inter-channel enhancements(color distortion)can often be observed in the resulting images.On the other hand,images with non-uniform illumination enhanced by the retinex algorithm are prone to artifacts such as local blurring,halos,and over-enhancement.To address these problems,an improved RGB color image enhancement method is proposed for images captured under nonuniform illumination or in poor visibility,based on weighted guided image filtering(WGIF).Unlike the conventional retinex algorithm and its variants,WGIF uses a surround function instead of a Gaussian filter to estimate the illumination component;it avoids local blurring and halo artifacts due to its anisotropy and adaptive local regularization.To limit color distortion,RGB images are first converted to HSI(hue,saturation,intensity)color space,where only the intensity channel is enhanced,before being converted back to RGB space by a linear color restoration algorithm.Experimental results show that the proposed method is effective for both RGB color and grayscale images captured under low exposure and non-uniform illumination,with better visual quality and objective evaluation scores than from comparator algorithms.It is also efficient due to use of a linear color restoration algorithm.

Effect of non-uniform illumination on performance of solar thermoelectric generators

Solar thermoelectric generators （STEGs） are heat engines which can generate electricity from concentrated sunlight. The non-uniform illumination caused by the optical concentrator may affect the performance of solar thermoelectric generators. In this paper, a three- dimensional finite element model of solar thermoelectric generators is established. The two-dimensional Gaussian distribution is employed to modify the illumination profiles incident on the thermoelectric generator. Six non-uniformities of solar illumination are investigated while keeping the total energy constant. The influences of non-uniform illumination on the temperature distribution, the voltage distribution, and the maximum output power are respectively discussed. Three thermoelectric generators with 32, 18 and 8 pairs of thermocouples are compared to investigate their capability under non-uniform solar radiation. The result shows that the non-uniformity of the solar illumination has a great effect on the temperature distribution and the voltage distribution. Central thermoelectric legs can achieve a larger temperature difference and generate a larger voltage than peripheral ones. The non-uniform solar illumination will weaken the capability of the TE generator, and the maximum output power decrease by 1.4% among the range of non-uniformity studied in this paper. Reducing the number of the thermoelectric legs for non-uniform solar illumination can greatly increase the performance of the thermoelectric generator.

电子计算机终端作业职业危害因素探讨

本文对长期从事VDT作业人员进行了调查。调查内容包括工作场所的微小气候(气温、相对湿度、风速、气压)、照明、噪声、空气离子、CO_2和细菌总数。还对57名VDT作业者和49名对照者进行了健康检查。结果表明,VDT作业场所噪声强度、空气中阳离子浓度较对照组高,照度低于标准,阴离子浓度比对照组低。VD T作业者主诉(头痛、头晕、记忆力减退、眼睛疲劳、关节酸痛、胸闷、乏力较对照组多。血小板中5-羟色胺含量较对照组明显增高。主要的职业危害因素有离子浓度改变,持续较高的噪声和较低的照度。

一种基于物理反射模型颜色不变性的阈值分割算法

提出了一种适用于视频监控场景的基于物理反射模型的阈值分割算法,该算法主要解决背景颜色识别受光强非均匀分布、高光效应影响的问题.算法步骤主要包括:首先基于Phong反射模型推导出漫反射分量颜色不变性并根据这一判定条件计算得到漫反射分量系数;其次,利用微分法则实现对模型镜面反射分量系数和镜面反射强度指数的估计;最后,根据建立的物理反射模型实现背景阈值分割.大量实验分析结果表明,文中提出的算法利用视频监控的物理反射模型和大量统计信息,能够更好地解决受光强非均匀分布和高光效应影响的颜色识别问题.

光照色调颜色恒常性算法研究

提出了一种新的适合于实时处理视频图像颜色识别的光照色调颜色恒常性算法。该算法主要解决在视频颜色识别中 ,由于近点光源的发散作用和在复杂背景影响下所造成的目标对象在图像局部各点上的颜色识别问题。在彩色感知的光学原理和数学模型基础上推导出了光照校正算法 ,并利用色调校正实现颜色恒常性。通过试验分析评估了各种识别算法 ,如光照校正、色调校正、光照色调校正、以及线性回归算法对颜色的校正效果 ,最后将测得的颜色差值和色调差值进行对比 ,证明了本算法对点光源散射作用引起的光照变化具有良好的校正作用 ,并证明了其算法理论推导的合理性。该算法的运算复杂度为 O(n) 。

一种亮度融合的视频增强方法

为了提高低照度视频的视觉效果,常常利用高质量白天亮度来增强夜间(低照度)视频。本文提出了一种亮度融合的视频增强方法。首先为了获取白天背景,采用了平均K帧的方法,然后使用Retinex理论,提取了白天背景和夜间视频帧的亮度,同时为了增强夜间移动物,采用帧差法提取了夜间视频帧的移动物,最后利用相同场景的白天背景亮度融合夜间帧的视频增强方法,为了改善夜间移动物体的感知度,提出了基于高斯滤波器的方法平滑移动物边界,使得增强结果更自然。实验结果表明了该算法在提高视觉质量上的有效性,且优于传统的方法。

利用β函数映射与帧间信息融合的低照度视频图像增强方法

在视频监控、视讯会议系统等应用领域,由于环境光照较低或背景光过强,常导致视频图像很多细节丢失,此时需要用视频增强技术来改善视频质量。本文提出了一种基于β函数映射与帧间信息融合的低照度视频图像增强方法。该方法在图像的照度层实现对比度增强,首先将视频图像从RGB空间转换到HSI色彩空间,提取其照度分量;然后用归一化非完全β函数的映射关系得到增强后的照度成分,β函数的参数通过本文提出的评价函数得到;最后,重建图像,完成视频图像的增强。与其他对比度增强方法相比,本文方法的增强效果好,且计算复杂度较小。文中给出了计算机仿真实验结果。

基于监督颜色恒常性的低照度亮度校正算法

提出了一种新的监督颜色恒常性算法,主要解决在机器视觉识别中由于色温变化所带来的光照校正问题。利用人类视觉对比度分辨率的限制规律,采用抛物线函数作为亮度增益函数,将图像亮度映射于实验确定的最佳识别范围。实验结果表明,该算法能够获得较理想的视觉校正效果,有效地提高识别率;不需要进行颜色空间转换,计算耗时少。

视频增强算法及其应用

针对传统视频增强算法中整体过度增强而忽略局部特征增强的缺陷,提出了一种有效的基于快速光照分割及分区映射的视频增强算法。首先从视频图像中提取运动目标和分离静态背景,通过快速分割方法将视频图像背景分成高光区、中等亮度区及暗光区,然后利用分区映射对不同亮度区分别进行增强。为了加强观察者对动态目标区域的视觉感知,基于区域亮度平均方法对运动区域作了进一步增强,以解决动态目标与增强背景不协调等现象。算法能够获得比传统视频增强技术更好的感知和亮度保持效果,可以直接运用到实时视频处理应用中。

低照度下视频图像保细节直方图均衡化方法

传统的直方图均衡化方法是通过对直方图中像素出现频率低的灰度等级进行合并实现的,表征图像细节的灰度等级往往被过度合并而使图像细节信息丢失。为解决上述问题,提出了一种改进的直方图均衡化方法,在对两个灰度是否合并进行判断时,根据两灰度等级的距离分别赋与按照一定步长递增的权重系数,避免了灰度等级的过度合并,较好地保留了图像的细节。同时提出了一种非线性灰度级映射变换方法,提高了图像的对比度和整体亮度。实验结果表明,新算法具有明显的改进效果。

低照度视频技术在综采工作面监控系统的应用

为实现综采工作面全景、动态、高清晰度的远程视频监控,将低照度视频技术应用于综采工作面监控系统,介绍了低照度视频技术应用原理和井下图像数据处理方法,并结合色调映射函数等光学计算公式,得到视频监视的镜头视场角参数。通过现场应用验证,应用低照度视频技术的综采工作面监控系统具有实时性好、流畅性佳和清晰度高等优势,能实现在综采工作面复杂、恶劣环境下采煤机、液压支架等设备的远程监控等功能。

一种去光照干扰方法在行人检测中的应用

在基于图像差分的行人检测算法中,光照的变化对提取图片中的行人干扰非常大,一般的自适应背景更新方法很难消除光照快速变化带来的影响。为了解决这一问题,设计了一种基于直方图分布特征相似性的光照变化干扰去除方法,分析了光照干扰前后两幅图片局部区域的直方图分布特征相似性原理,给出了图像直方图分布特征相似性测量方法及评价参数——标准差。通过对光照频繁变化环境下相邻两帧图片进行差分实验,结果表明,该方法能够克服光照突然变化的干扰且鲁棒性好,能够准确分割出运动目标和抑制大幅度光照变化带来的干扰。