基于双边滤波的HDR图像色调映射算法

高动态范围(HDR)图像是一种表达了超过一般显示器所能表示的真实场景中亮度大范围变化的图像类型,能够很好地区分场景的明暗区域,呈现更多的细节信息.为了能够在低动态范围显示器上显示HDR图像,需要进行动态范围压缩.采用一种基于双边滤波的HDR图像动态范围压缩算法,首先计算每个像素点亮度值,然后对其进行双边滤波处理,最后进行对比度的压缩并生成最终的图像.实验结果表明,该算法合成的HDR图像整体明暗效果较好,细节信息丰富.     

基于移动最小二乘的高分辨HDR图像色调映射算法

HDR图像由于能够同时很好地保存图像亮区和暗区的信息而受到越来越多的关注,但是没有办法在普通的显示设备上进行很好的显示.所以出现了很多对于HDR图像进行色调映射的算法.但是,对于高分辨率HDR图像的色调映射,目前还缺乏比较有效的方法.本文提出了一种针对高分辨率HDR图像色调映射的有效方法.该方法先利用移动最小二乘法提取图像的光照分量,然后对其进行压缩后再恢复图像的彩色信息.实验表明所提方法能够快速处理任意分辨率的HDR图像,而且同时能够很好地在普通显示设备上显示图像亮区和暗区的细节信息.     

一种基于色调/饱和度/亮度彩色空间的灰度变换算法

考虑到灰度变换技术直接应用于RGB彩色图像增强容易引起彩色失真的缺陷,提出了一种自适应灰度变换算法,将原始RGB图像和RGB三分量灰度变换后的图像转换到色调／饱和度／亮度彩色空间,重组两者的色调分量和亮度分量,再对原始图像的饱和度分量进行补偿处理,从而保持了原始图像的色彩．本算法充分继承了灰度变换算法的优点,扩展了原始图像的有效灰度范围,提高了整体对比度,增强了细节．此外,算法的计算量极小,不需要设定任何参数,可用于自适应实时彩色图像处理．     

参数控制的混合色调映射方法

为解决高动态图像的真实影像再现问题,提出了一种基于参数控制的混合色调映射方法.对图像进行全局预处理,保持整幅图像的亮度和对比度;采用参数控制的混合算子获取图像的局部对比度和细节;采用双边滤波解决色调映射过程中产生的光晕问题.仿真实验表明,该方法压缩了原始高动态图像的动态范围,保持了整体亮度,增强了局部细节而去除光晕效应影响,比现有的Sigmoid算法在各个参数上有显著提高.      

具有细节补偿和色彩恢复的多尺度Retinex色调映射算法

针对带色彩恢复的多尺度Retinex色调映射算法(MSRCR)在分离图像光照信息时未保留部分细节信息,导致结果图像出现细节模糊和颜色失真的问题,提出了一种具有细节补偿和色彩恢复的多尺度Retinex色调映射算法(MSRCD).该算法利用Retinex理论的基本原理将高动态范围图像分为反射层和光照层,先使用双边滤波从图像光照层中提取出细节信息进行补偿,然后从图像的反射层中分离出基本层信息并进行自适应调整,压缩其动态范围,最后通过色彩校正还原图像颜色.实验结果表明,与MSRCR算法及基于双边滤波的算法相比,MSRCD算法的处理结果保留了更丰富的细节信息,色彩逼近于真实场景且避免了光晕的产生.     

采用主成分分析与梯度金字塔的高动态范围图像生成方法

针对由多曝光低动态范围(LDR)图像融合生成高动态范围(HDR)图像对采集设备要求高且不适用于动态场景的问题,提出一种采用主成分分析(PCA)与梯度金字塔的HDR图像生成(HDR-PGG)方法。首先用改进的S曲线全局映射和Retinex局部色调映射对PCA变换后的亮度图像进行处理,以避免光晕和泛灰,并结合PCA逆变换获取多曝光LDR图像;其次利用多曝光LDR图像的对比度、饱和度、曝光度和亮度信息构造标量权重图,确保生成的HDR图像亮暗区域分明且细节清晰;最后,利用梯度金字塔生成HDR图像。实验结果表明,当视觉差异大于75%时,由HDR-PGG方法生成的HDR图像的平均像素分布概率比拉普拉斯金字塔和梯度金字塔算法降低了10.84%和30.75%,其平均相对熵与噪声程度比值分别提高了0.542 1和0.508 9。     

基于协同滤波的多尺度色调映射

高动态范围(HDR)图像是一类包含丰富的图像细节、具有较高明暗对比度、接近真实场景色彩的图像.HDR图像具有广阔的研究前景和实际应用价值.与传统图像相比,这类图像具有很高的动态范围,因而HDR图像在一般显示设备上难以得到比较满意的显示效果.为了克服这一问题,本文提出一个基于协同滤波的多尺度色调映射模型,该模型先利用滤波方法将HDR图像分解为不同细节尺度的图像层,再对各个图像层的动态范围进行不同程度的调整,从而同时达到压缩动态范围和增强细节的效果.实验表明该模型能较好地在一般显示设备重现原场景,具有较好的视觉效果.     

双能X射线高动态范围安检图像压缩算法

为使拥有高动态范围的双能X射线安检图像在普通显示器上显示时不丢失细节,提出了一种基于多尺度局部保边(local edge-preserving,LEP)滤波的自适应色调映射算法.该算法对原始图像进行多尺度LEP滤波,得到1个基础层和3个细节层.随后对基础层进行对数自适应色调映射,并对3个细节层进行Sigmoid函数自适应增强.将处理后的各层图像相加,并进行直方图均衡化调整以去除噪声、提高图像对比度.该算法同时对高、低能X射线图像进行处理,并在处理后根据高、低能图像各自的特点进行融合,最终得到保留丰富信息的低动态范围双能X射线图像.实验表明,该算法在信息熵、对比度提升指数及峰值信噪比三方面都有提高,能够有效改善图像质量.     

基于色调映射和暗通道融合的弱光图像增强

针对阴天或夜晚等弱光条件下拍摄的图像具有亮度低、对比度低和细节模糊等问题,提出了一种基于色调映射和暗通道融合的弱光图像增强方法.首先,根据弱光及其反转图像的特点,提出面向弱光图像的透射率估计方法,进而获得场景深度信息,并将其融入色调映射函数设计;同时利用暗通道图像区分光源区域,以修正色调映射函数参数,使其能够根据场景深度自适应调整图像亮度;另一方面,增强后的暗通道图可有效突出图像的细节信息,将经过色调映射后的V通道图像和暗通道图进行加权融合,得到最后的增强结果.实验结果表明,本文方法不仅显著改善图像亮度、增强对比度、恢复出更多的图像细节,还能有效去除块效应和晕轮伪影,视觉效果理想.     

基于图像分割和融合的图像去雾算法研究

为了解决传统的暗通道先验去雾方法产生的细节丢失和亮度偏低等问题,本研究提出了一种基于图像分割和融合的去雾算法。首先对输入图像使用亮度反转的MSRCR预处理来进行色彩保真;其次用阈值分割法提取图像的特征信息并获得掩膜,根据特征信息设计自适应的Gamma校正方法,提升对比度和亮度,并使用暗通道先验方法保持去雾后的细节;最后将处理后的图像进行掩膜融合。在真实世界的数据集上仿真结果表明,本研究所提算法在去雾后能保留更多的细节且提高亮度。与几种经典的算法相比,本研究所提算法在去雾后的图像有较好的色彩保真度,保留了更多的细节,去雾效果好且亮度更自然。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.