Modelling of chromatic contrast for retrieval of wallpaper images

Colour remains one of the key factors in presenting an object and, consequently, has been widely applied in retrieval of images based on their visual contents. However, a colour appearance changes with the change of viewing surroundings, the phenomenon that has not been paid attention yet while performing colour‐based image retrieval. To comprehend this effect, in this article, a chromatic contrast model, CAMcc, is developed for the application of retrieval of colour intensive images, cementing the gap that most of existing colour models lack to fill by taking simultaneous colour contrast into account. Subsequently, the model is applied to the retrieval task on a collection of museum wallpapers of colour‐rich images. In comparison with current popular colour models including CIECAM02, HSI and RGB, with respect to both foreground and background colours, CAMcc appears to outperform the others with retrieved results being closer to query images. In addition, CAMcc focuses more on foreground colours, especially by maintaining the balance between both foreground and background colours, while the rest of existing models take on dominant colours that are perceived the most, usually background tones. Significantly, the contribution of the investigation lies in not only the improvement of the accuracy of colour‐based image retrieval but also the development of colour contrast model that warrants an important place in colour and computer vision theory, leading to deciphering the insight of this age‐old topic of chromatic contrast in colour science. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 361–373, 2015     

光传送网中的关键光器件

光器件是光传送网的基础单元之一，本主要综述光传送网中的关键光器件：光源与光探测器、光波分复用/解复用器、光放大器、色度色散与偏振模补偿器及光开关等。比较了各种光器件的主要技术方案，特别针对的是已实用化的技术方案。最后讨论了光器件的尺寸小型化、微型化以及多功能集成等发展趋势，介绍了光器件的集成方式如：传统分立光器件的集成，平面光波导集成，以及混合集成等。     

光纤色散测量概述

介绍了三种最为成熟的光纤色散测量方法:时延法、相移法和干涉法,并从色散测量原理、测量装置、适用范围以及优缺点等几方面进行了论述.时延法测量精度不高,目前较少采用;相移法测量精度高,但测量仪器价格昂贵,测量成本高;干涉法既能满足一定的测量精度要求(时间分辨率可达1ps),又控制了测量成本,是普遍采用的测量方法.     

高速光通信系统中的色散问题及其补偿研究

当光纤通信系统单信道速度升级到40Gbit/s及以上时，色度色散（CD）和偏振模色散（PMD）已经成为严重影响系统性能的主要因素。本文主要从补偿的必要性、关键技术、主要方法和解决方案等方面分别对CD和PMD及其补偿进行了较详细的研究。     

Transmission Fiber Chromatic Dispersion Dependence on Temperature: Implications on 40 Gb/s Performance

In this letter, we will evaluate the performance degradation of a 40 km high‐speed (40 Gb/s) optical system, induced by optical fiber variations of the chromatic dispersion induced by temperature changes. The chromatic dispersion temperature sensitivity will be estimated based on the signal quality parameters.     

基于Luv色度坐标图像分割方法的孔洞参数计算

针对成像测井解释中孔洞参数定量计算的准点，提出用基于Luv色度坐标进行图像分割的方法来定量计算孔洞的面积、面孔率等相关参数。采用该方法得到的孔洞结果目标区域完整，可以方便地计算出孔洞面积和面孔率等参数。     

Chromatic induction: Opponent color or complementary color process?

In present convention, chromatic induction (simultaneous and successive contrast) is usually held to be an opponent color process. Fifty years ago, it was an accepted complementary color process. The latter was never disputed yet apparently overlooked, and is here shown to be the more accurate account by inspecting afterimages and published data on simultaneous and successive hue induction. © 2007 Wiley Periodicals, Inc. Col Res Appl, 33, 77–81, 2008     

计算机配色技术应用于木材染色初探

介绍了计算机测色配色系统的原理,研究了建立木材染色基础数据库的方法,提出了注意事项,并分析了自动配色过程中产生色差的原因及解决方法。     

Chromatic luminance,colorimetric purity,and optimal aperture‐color stimuli

Chromatic luminance (i.e., luminance of a monochromatic color) is the source of all luminance, since achromatic luminance arises only from mixing colors and their chromatic luminances. The ratio of chromatic luminance to total luminance (i.e., chromatic plus achromatic luminance) is known as colorimetric purity, and its measurement has long been problematic for nonspectral hues. Colorimetric purity (p_c) is a luminance metric in contrast to excitation purity, which is a chromaticity‐diagram metric approximating saturation. The CIE definition of p_c contains a fallacy. CIE defines maximum (1.0) p_c for spectral stimuli as monochromatic (i.e., optimal) stimuli, and as the line between spectrum ends for nonspectrals. However, this line has <0.003 lm/W according to CIE colorimetric data and is therefore effectively invisible. It only represents the limit of theoretically attainable colors, and is of no practical use in color reproduction or color appearance. Required is a locus giving optimal rather than invisible nonspectral stimuli. The problem is partly semantic. CIE wisely adopted the term colorimetric purity, rather than the original spectral luminance purity, to permit an equivalent metric for spectrals and nonspectrals, but the parameter of equivalence was never clear. Since 1 p_c denotes optimal aperture‐color stimuli for spectrals, arguably 1 p_c should denote optimal stimuli consistently for all stimuli. The problem reduces to calculating optimal aperture‐color stimuli (“optimal” in energy efficiency in color‐matching) for nonspectrals, shown to comprise 442 + 613 nm in all CIE illuminants. This remedy merely requires redefinition of 1 p_c for nonspectrals as the line 442–613 nm, and gives meaningful p_c values over the hue cycle allowing new research of chromatic luminance relations with color appearance. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 469–476, 2007