Single-image night haze removal based on color channel transfer and estimation of spatial variation in atmospheric light

The visible-light imaging system used in military equipment is often subjected to severe weather conditions, such as fog, haze, and smoke, under complex lighting conditions at night that significantly degrade the acquired images. Currently available image defogging methods are mostly suitable for environments with natural light in the daytime, but the clarity of images captured under complex lighting conditions and spatial changes in the presence of fog at night is not satisfactory. This study proposes an algorithm to remove night fog from single images based on an analysis of the statistical characteristics of images in scenes involving night fog. Color channel transfer is designed to compensate for the high attenuation channel of foggy images acquired at night. The distribution of transmittance is estimated by the deep convolutional network DehazeNet, and the spatial variation of atmospheric light is estimated in a point-by-point manner according to the maximum reflection prior to recover the clear image. The results of experiments show that the proposed method can compensate for the high attenuation channel of foggy images at night, remove the effect of glow from a multi-color and non-uniform ambient source of light, and improve the adaptability and visual effect of the removal of night fog from images compared with the conventional method.

Light and Shadow:Hu Xinyu's 2019 AW Men's Wear Fashion Show

On March 30th 2019, Chinese independent designer, Hu Xinyu presented his own brand’s autumn and winter men’s ready-to-wear line (XINYUHU2019). This work showcased an avantgarde, comfortable and concise design style. He used stripes, geometric patterns and other elements to highlight specific elements and applied techniques of hairy edge, asymmetric collage;he explained the charm of practical aesthetics to the audience.

A General Channel Model for Visible Light Communications in Underground Mines

In underground mines, visible light communication(VLC) system is a promising method to realize effective communication,which supports communication and illumination at the same time. Therefore, adequate research of underlying physical propagation phenomenon should be carried out to realize VLC system in underground mines. To design VLC system and evaluate its performance, accurate and efficient channel models, including large-scale fading and scattering characteristics, are needed to be established. However,the characteristics of the underlying VLC channels about fading and scattering have not been sufficiently investigated yet. In this paper, a path loss channel model, based on the recursive model, is proposed precisely. Its path loss exponent is determined by three different trajectories, which is studied in the mining roadway and working face environment. Besides, the shadowing effect for VLC has been modelled by a Bimodal Gaussian distribution in underground mines. Considering the number of transmitters in line-of-sight(Lo S) as well as non-line-of-sight(NLo S) scenarios,our simulation illustrates the fact that, as the curve fitting technique is employed, the path loss displays a linear behavior in log-domain.The path loss expression is derived, it is related to the distance. Finally, root mean square(RMS) delay spread and Mie scattering in underground mines are analyzed.

Light-scattering model for aerosol particles with irregular shapes and inhomogeneous compositions using a parallelized pseudo-spectral time-domain technique

To improve the modeling accuracy of radiative transfer,the scattering properties of aerosol particles with irregular shapes and inhomogeneous compositions should be simulated accurately.To this end,a light-scattering model for nonspherical particles is established based on the pseudo-spectral time domain(PSTD)technique.In this model,the perfectly matched layer with auxiliary differential equation(ADE-PML),an excellent absorption boundary condition(ABC)in the finite difference time domain generalized for the PSTD,and the weighted total field/scattered field(TF/SF)technique is employed to introduce the incident light into 3 D computational domain.To improve computational efficiency,the model is further parallelized using the Open MP technique.The modeling accuracy of the PSTD scheme is validated against Lorenz–Mie,Aden–Kerker,T-matrix theory and DDA for spheres,inhomogeneous particles and nonspherical particles,and the influence of the spatial resolution and thickness of ADE-PML on the modeling accuracy is discussed as well.Finally,the parallel computational efficiency of the model is also analyzed.The results show that an excellent agreement is achieved between the results of PSTD and well-tested scattering models,where the simulation errors of extinction efficiencies are generally smaller than 1%,indicating the high accuracy of our model.Despite its low spatial resolution,reliable modeling precision can still be achieved by using the PSTD technique,especially for large particles.To suppress the electromagnetic wave reflected by the absorption layers,a six-layer ADE-PML should be set in the computational domain at least.

Automatic detection and removal of static shadows

In case of complex textures,existing static shadow detection and removal algorithms are prone to false detection of the pixels.To solve this problem,a static shadow detection and removal algorithm based on support vector machine(SVM)and region sub-block matching is proposed.Firstly,the original image is segmented into several superpixels,and these superpixels are clustered using mean-shift clustering algorithm in the superpixel sets.Secondly,these features such as color,texture,brightness,intensity and similarity of each area are extracted.These features are used as input of SVM to obtain shadow binary images through training in non-operational state.Thirdly,soft matting is used to smooth the boundary of shadow binary graph.Finally,after finding the best matching sub-block for shadow sub-block in the illumination region based on regional covariance feature and spatial distance,the shadow weighted average factor is introduced to partially correct the sub-block,and the light recovery operator is used to partially light the sub-block.The experimental results show the number of false detection of the pixels is reduced.In addition,it can remove shadows effectively for the image with rich textures and uneven shadows and make a natural transition at the boundary between shadow and light.

Measurements of NO_2 mixing ratios with topographic target light scattering-differential optical absorption spectroscopy system and comparisons to point monitoring technique

A topographic target light scattering-differential optical absorption spectroscopy （＇IbTaL-DOA~） system is de- veloped for measuring average concentrations along a known optical path and studying surface-near distributions of atmospheric trace gases. The telescope of the ToTaL-DOAS system points to targets which are located at known dis- tances from the measurement device and illuminated by sunlight. Average concentrations with high spatial resolution can be retrieved by receiving sunlight reflected from the targets, A filed measurement of NO2 concentration is performed with the ToTaL-DOAS system in Shijiazhuang in the autumn of 2011. The measurement data are compared with con- centrations measured by the point monitoring technique at the same site. The results show that the ToTaL-DOAS system is sensitive to the variation of NO2 concentrations along the optical path.

The effects of radio frequency atmospheric pressure plasma and thermal treatment on the hydrogenation of TiO_(2) thin film

The effects of radio frequency(RF)atmospheric pressure(AP)He/H_(2)plasma and thermal treatment on the hydrogenation of TiO_(2)thin films were investigated and compared in this work.The color of the original TiO_(2)film changes from white to black after being hydrogenated in He/H_(2)plasma at160 W(gas temperature~381℃)within 5 min,while the color of the thermally treated TiO_(2)film did not change significantly even in pure H_(2)or He/H_(2)atmosphere with higher temperature(470℃)and longer time(30 min).This indicated that a more effective hydrogenation reaction happened through RF AP He/H_(2)plasma treatment than through pure H_(2)or He/H_(2)thermal treatment.The color change of TiO_(2)film was measured based on the Commission Internationale d’Eclairage L*a*b*color space system.Hydrogenated TiO_(2)film displayed improved visible light absorption with increased plasma power.The morphology of the cauliflower-like nanoparticles of the TiO_(2)film surface remained unchanged after plasma processing.X-ray photoelectron spectroscopy results showed that the contents of Ti3+species and Ti-OH bonds in the plasma-hydrogenated black TiO_(2)increased compared with those in the thermally treated TiO_(2).X-ray diffraction(XRD)patterns and Raman spectra indicated that plasma would destroy the crystal structure of the TiO_(2)surface layer,while thermal annealing would increase the overall crystallinity.The different trends of XRD and Raman spectra results suggested that plasma modification on the TiO_(2)surface layer is more drastic than on its inner layer,which was also consistent with transmission electron microscopy results.Optical emission spectra results suggest that numerous active species were generated during RF AP He/H_(2)plasma processing,while there were no peaks detected from thermal processing.A possible mechanism for the TiO_(2)hydrogenation process by plasma has been proposed.Numerous active species were generated in the bulk plasma region,accelerated in the sheath region,and bumped toward the TiO_(2)film,which will react with the TiO_(2)surface to form OVs and disordered layers.This leads to the tailoring of the band gap of black TiO_(2)and causes its light absorption to extend into the visible region.

宜家产品数字化交互体验设计研究--以家具产品互动光影体验设计为例

随着智能科技的不断革新,宜家也开启了数字化转型发展,产品的数字化交互体验成为了转型发展中的重要目标任务,这给宜家家具产品在体验维度方面也带来了扩展与变化。通过分析相关用户行为数据与体验设计理论,结合宜家家具产品光影互动交互体验设计实践案例,分析了宜家产品数字化特性,探讨了构建宜家产品数字化体验的四个体验维度,对宜家产品数字化体验设计流程与方法进行了归纳总结,构建提出了宜家产品数字化交互体验特征维度模型,为宜家产品数字化体验转型提供了解决方法与路径。

陆地生态系统碳监测卫星自主任务规划研究

低轨遥感卫星往往以全球或全国范围内的特定地物为探测目标。为提高卫星在轨运行的自主性,文章提出了一种面向地物目标属性的遥感卫星自主任务规划方法。首先外推出预报点90 min后的星下点经纬度,并根据星载地图和太阳高度角,得到预报点的阳照/阴影、陆地/海洋、境内/境外属性。对地物目标属性信息进行平滑处理后,根据各载荷的地物目标属性,识别出各载荷的工作任务时间段,可实时实现提前约1个轨道圈的载荷自主任务规划。

改进型大气散射模型下的双光幕约束雾图复原算法

当雾霾退化场景处于光照不均匀的条件下时,部分场景细节不仅会由于雾气遮盖导致可见度降低,同时会因为光照阴影使得部分区域不可见。针对这一问题,提出一种基于改进型大气散射模型的双光幕边界约束的雾天图像复原算法。分析传统大气散射模型的成像原理,利用其退化机理结合Retinex理论对模型进行改进;引入均值不等关系与高斯衰减函数,通过预估特征值的方法对大气光幕进行估计,并设定上下边界对其进行约束;依照改进型大气散射模型求取场景入射光,并利用亮通道先验求取有雾图像亮通道对场景入射光进行补偿;改进局部大气光的获取方法,提出基于中通道的局部大气光估计方法,结合所求大气光幕与场景入射光代入改进型大气散射模型获得无雾图像,并使其与图像纹理层进行融合得到最终的复原结果。根据对实验结果的定性与定量分析,所提算法不仅可以有效复原出场景光照不均的有雾图像,针对其余场景下的雾霾场景也可得到较好的复原效果,且复原场景清晰,明亮度适宜。

氛围之上:北京上地·元中心景观设计创作复盘

【目的】气氛美学之于景观设计创作是一个当代命题,又可与中国传统意境美学互为参照,氛围设计逐渐发展成为一种需要不断建构和修正的景观理论。【方法/过程】以北京上地·元中心科技园景观从概念到落地呈现的设计创作为研究对象,重点解析其中最具代表性的“圆舞曲之庭”和“后工业基因城市绿带”两个重点部分的设计演进过程。【结果/结论】以实证回溯的方式复盘讨论了在本次设计实践中将“氛围”作为总体前置的景观设计控制方法的路径择取、空间应变和价值拓展。

基于天空区域分割的快速去雾算法研究

针对传统暗通道先验去雾算法在处理户外含雾图像时,出现天空区域颜色失真和处理速度慢的问题,提出一种可自适应识别天空区域的快速去雾算法。在天空分割方面,选用图像中细节特点明显的亮度分量为研究对象,结合最大类间方差法(OTSU)和动态参数建立自适应识别天空区域算法模型,得到最佳分割阈值,分割出有雾图像的天空区域和非天空区域,并根据天空区域计算出大气光值。在提高处理速度方面,在使用引导滤波优化透射率过程中引入图像下采样算法,保证复原后图像质量的同时减少算法耗时。最后经过与多种经典算法对比,文中算法在视觉效果上细节更加自然,SSIM、PSNR和MSE的综合指标均超过其他算法,并且处理速度较快。主观和客观评价结果均表明,文中算法在视觉效果和时间效率方面都优于其他几种算法,具有一定的实用价值。

基于自适应大气光值补偿的改进暗通道煤矿井下图像去雾算法(特邀)

视频监控是保障工业生产和人员安全的重要手段。但在一些特殊领域,监控图像常会受到粉尘散射的影响而产生雾化现象、导致图像质量退化。此外,由于这些生产环境在照明、目标景物方面具有特殊性,常用的暗通道去雾算法存在色彩偏移、过暗、光晕等现象。以煤矿井下监控图像为目标,针对井下粉尘、水雾导致图像模糊、照度低、色彩信息不丰富的问题,提出一种改进的快速暗通道算法。该算法对大气光值进行基于像素自身颜色信息的自适应补偿校正,以减小色偏的产生,并针对井下图像提出了自拟合的亮度和饱和度增强函数。除对井下图像进行处理外,还将该算法用于常用去雾图像数据集,结果表明该算法对多种场景在有效去雾的同时很好地矫正了色偏及光晕现象,并提高了亮度和色彩饱和度。该算法为井工煤矿等产业以及生活场景的去雾提供了一种新的手段。

基于变异鸡群优化透射率估计的去雾算法

在大雾天气下,收集的图片存在清晰度降低和颜色畸变等问题。为获得高质量的去雾图像,文中提出了一种混合暗通道去雾算法。该算法使用Retinex算法去除照射分量的干扰,采用变异鸡群优化算法获得引导滤波所需的导向图片来优化大气透射率,并应用改进的暗通道先验算法来获得去雾图像。相较于其他暗通道先验去雾算法,该方法的平均标准差降低了28.3%,平均峰值信噪比增长了10.3%,平均熵增加了8.0%。测试了同一个场景中不同雾霾程度下的图片,结果显示图片清晰,细节信息保留完整,且评价标准数值基本保持稳定。测试结果表明,所提算法具有较高的鲁棒性和良好的色彩保真能力。

基于高斯模型与自适应大气光幕的图像去雾算法

单幅图像去雾被广泛应用于户外光学图像采集设备,针对现有算法去雾不彻底、偏色的问题,提出了一种基于高斯模型与自适应大气光幕的去雾算法。首先,通过离散余弦变换分离出有雾图像的低频分量,并且利用低频分量和大气光幕的线性关系结合高斯函数,提出一个自适应大气光幕求取模型,获得初始大气光幕;随后,结合伽马校正构造一个含有未知参数的优化函数,并对大气散射模型施加平均饱和度先验,获得最终的自适应大气光幕;最后,通过大气散射模型获得清晰无雾图像。实验表明,该算法与一些经典和先进算法相比较,具有很强的泛用性,复原结果清晰、颜色自然,在一些客观评价指标上也优于其他对比算法。

油画的韵律:印象派大师莫奈的光影表达

本篇文章深入研究了19世纪法国的印象派画家“印象派之父”克洛德·莫奈的油画作品,光影表达是他的作品画面中的最大特点,本文以莫奈在油画界中所产生的艺术成就与贡献入手,结合莫奈的绘画特征与作品,分析其画面中的光与影,重点探讨他如何通过光影的变化、色彩的丰富和对自然的感知,创造出富有韵律感的画面,以及这种表达如何在印象派运动中发挥了重要作用。

基于WRF模式高光谱分辨率测温激光雷达系统分析

为了解析大气瑞利-布里渊散射光谱并获取0 km~16 km的大气垂直温度廓线,采用基于菲索干涉仪结合光电倍增管阵列的高光谱分辨率测温激光雷达(HSRL)对不同季节环境下的温度反演能力及系统误差进行了理论分析,得到了利用大气瑞利-布里渊散射光谱在结合Tenti S6模型进行拟合的情况下,不同的大气模型对温度廓线拟合的影响结果。结果表明,使用US76大气模型结合Tenti S6模型,经10000次脉冲积分后,在0 km~16 km范围内的最大随机误差为1.1 K;使用天气预报模式(WRF)提供的温压场代替US76模型的温压场进行模拟,随机误差随季节略有不同,春季不超过0.65 K,夏季不超过0.98 K,秋季不超过0.59 K,冬季不超过0.63 K;使用WRF模式进行HSRL系统探测能力评估结果优于使用US76的评估结果,若精选不同天气类型,该方法还可以拓展到评估不同季节下HSRL的随机误差,体现了将WRF模式用于HSRL评估的优势。该研究为HSRL测温系统在不同季节下的工作能力评估提供了参考。

大气湍流和大气闪烁对激光通信性能的影响分析

分析大气湍流和大气闪烁对激光通信性能的影响,最大程度提升激光通信质量。以构建的大气湍流下激光通信信道传输模型为基础,分析大气湍流引起激光通信光束折射率分布不均匀情况导致激光光束光强分布出现涨幅产生的大气闪烁现象,并计算大气光强闪烁指数,结合激光通信系统接收信号瞬时信噪比的概率密度函数,分析大气湍流和大气闪烁对激光通信中断概率、平均误码率、平均信道容量的影响;实验结果显示:降低传输距离和天顶角、增加接收端孔径和平均信噪比可降低大气湍流时大气闪烁对激光通信性能的影响;低阶激光光束面对强大气湍流的光束大气闪烁指数变化更显著,可通过提升激光光束阶级提升激光通信质量;且OAM光束相对于高斯光束可更好地抵抗大气湍流和大气闪烁对激光通信性能产生的影响。

结合自适应融合和双边界光幕估计的图像去雾

针对图像去雾算法存在的细节丢失、颜色失真、去雾不彻底等问题,提出一种利用通道估计光幕上下边界、自适应融合大气光的去雾算法。首先,根据有雾图像最小通道估计大气光幕上边界,以雾图B通道为主、RG通道差补偿结合线性变换得到大气光幕下边界,对上下边界进行逼近优化,经过小波变换融合两边界;其次,分别用RGB三通道的平均值和亮度中通道获取不同的粗糙大气光,以亮度均值为调节因子自适应融合;最后,结合去雾模型复原出无雾图像。实验结果表明,所提算法复原的图像去雾彻底、清晰自然、能保留较多图像细节,具有良好的有效性和鲁棒性。

基于不均匀光照校正和优化透射率的夜间去雾

针对夜间有雾天气场景下的光照不均匀、图像不清晰问题,提出了一种基于夜间不均匀光照校正和优化透射率的去雾算法。首先针对光照不均匀问题,使用基于伽马函数的图像自适应校正算法,消除不均匀光照对图像的影响;其次,由于夜间图像大部分颜色较暗,通过改进局部大气光获得大气光值;利用Sigmoid函数融合亮通道与暗通道得到粗透射率,经过联合双边滤波细化,再对光源处透射率进行优化,并使用伽马函数增强得到最终透射率;然后根据大气散射模型得到初步恢复图像;最后经过引导滤波细化,得到最终图像。实验结果表明所提算法在夜间场景中能有效去雾,且能较好的保持图像颜色对比度。