Upper-limit luminance for the surface-color mode appearance

A series of experiments were carried out to reveal determinants for the mode of color appearance by measuring the upper-limit luminance of a color chip for the surface-color mode. We used a CRT color monitor to present test and surround stimuli in the surface-color mode. The stimuli were composed of a three-by-three array of color chips on a gray background with a white frame. The observer increased the luminance of a center test color until it just ceased to appear in the surface-color mode. Our results show that this upper-limit luminance was different among test colors, but their brightnesses, calculated from the luminance and brightness/ luminance values, were almost the same and were slightly below the brightness of the white frame. The existence of the surrounding color chips affected the results, but their sizes and spatial arrangements did not. When all of the luminances of the surrounds changed equally, the upper-limit luminances of the test colors for the surface-color mode appearance changed by the same ratio. This result indicates that the brightness of a target was a determinant for selecting the mode of color appearance and that the brightest surround stimulus acted as a cue for determining the judgment.     

Bioinspired Color Materials Combining Structural,Dye, and Background Colors

Human beings have developed many dyes and pigments and use them for printed and display materials to share information. Today's information society is not possible without these color materials. Some living organisms utilize body color for information exchange and protection by skilfully combining dye, structural, and background colors to realize a body color change based on circumstances. In this study, inspired by the extraordinary body color changes of living things, a composite color material combining photochromic dyes, a black substance, a spherical colloidal crystal exhibiting a structural color, and a background color is prepared. In addition to combining a dye color and a structural color that changes upon light irradiation, the contribution of the different effects of the background color on each coloring property allows the construction of a color material that can reversibly change into various colors under different conditions.     

四季联想与治愈系色彩的智能生成

目的 由于对四季的联想有心理治愈的效果，所以以智能化方法生成四季治愈系色彩构成，并结合最典型的四季风物，展开对公交客车外饰配色的创新设计。方法 首先，通过实验获取四季治愈系色彩的基本数据，以获取的四季治愈系色彩为依据，构建四季治愈系色彩的蒙赛尔色彩空间，并对四季治愈系色彩进行可视化呈现;其次，通过对大量色彩数据的“除燥处理”，智能化生成了四季治愈系的色彩构成;最后，选出最典型的四季联想风物，利用格式塔图形原理将典型风物外形与四季治愈系色彩结合，对公交客车外饰进行四季治愈系配色。结论 实验结果说明:四季公交客车外饰配色设计能够联想四季感起到治愈效果，以公交客车四季外饰配色为案例的设计方法具有广泛的应用前景。     

Increments and decrements in color constancy

The present study examines whether increment-decrement asymmetries reported in a number of recent center-surround situations occur in more complex images as well. Subjects saw the CRT simulation of a whole uniformly illuminated array of foreground surfaces presented against a large background surface and, for a number of different viewing contexts, made achromatic settings over a wide range of luminance values. Three results emerged. First, subjects' achromatic loci did not fall on a single straight line in color space but rather fell on two separate lines intersecting at some point in this space. Second, the intersection points were not identical to but dependent largely on background color and showed only small effects of foreground colors. Third, cone signals that were decremental relative to the intersection point were more responsive to illuminant changes than cone signals that were incremental, the latter additionally showing some variation with foreground colors. The results are interpreted in terms of increment-decrement asymmetries. They suggest that these asymmetries occur in more complex images as well.     

基于K-means聚类的马王堆帛画色彩特征分析与应用

目的 提取马王堆帛画特征色彩,分析帛画色彩间配色关系,为文创产品设计的配色过程提供指导,在设计中更加准确地展现帛画的文化特色。方法 首先使用优化后的K-means聚类算法提取出帛画的特征色彩,生成帛画的标准色卡;然后利用图像中的色彩占比数据和色彩邻接关系,建立色彩网络模型,确定色彩主辅色搭配;最后利用CorelDRAW插件color shuffle自动生成多个配色种群,使用模糊综合评价方法验证帛画特征色彩提取的可行性与运用色彩网络模型辅助配色的可操作性。结论 使用K-means聚类方法提取出的帛画标准色卡应用于设计时具有色彩代表性,构建色彩网络模型和插件辅助配色能够提高设计师的配色效率,为文创产品的配色设计过程提供了新的思路。     

QR码直接扩容技术

目的针对黑白QR码信息嵌入能力不足以及大容量信息存储的需求,提出一种QR码直接扩容技术。方法黑白QR码只有2种颜色的编码模块,每个编码模块存储1比特数据;彩色QR码拥有2n种颜色的编码模块,每个编码模块存储n比特数据,使QR码存储容量直接扩增n倍。基于HSV颜色空间模型,采用三元组配色模型进行编码模块的配色,以降低彩色编码模块间的混叠效应。采用图像对比度增强和K-Means聚类算法处理彩色编码模块的颜色偏离。结果通过对拥有16种颜色编码模块的彩色QR码数据存储性能进行分析可知,存储相同容量的数据信息,彩色QR码比黑白QR码的版本更低,QR码符号更小,实现了QR码存储容量的直接扩增。结论采用QR码直接扩容技术可实现存储容量的倍数扩增;采用K-Means聚类算法可大幅度降低彩色QR码编码模块之间的混叠效应,显著提高彩色QR码译码的正确率。     

Induction effects for heterochromatic brightness matching, heterochromatic flicker photometry, and minimally distinct border: implications for the neural mechanisms underlying induction

Brightness induction refers to the finding that the apparent brightness of a stimulus changes when surrounded by a black versus a white stimulus. In the current study, we investigated the effects of black/white surrounding stimuli on settings made between red and green stimuli on three different tasks: heterochromatic brightness matching (HBM), heterochromatic flicker photometry (HFP), and minimally distinct border (MDB). For HBM, subjects varied the relative luminance between the red and green stimuli so that the brightness of the two colors appeared equal. For the two other tasks, matches were made based on minimizing red/green flicker (HFP) or the saliency of a red/green border (MDB). For all three tasks, the presence of black/white surrounding stimuli significantly altered red/green settings, demonstrating the existence of induction effects. These results are discussed in terms of which underlying color pathways (L+ M versus L-M) may contribute to induction effects for the different tasks.     

色貌模型在跨媒体图像复制中的应用研究

目的 研究CIECAM02和iCAM色貌模型颜色空间的均匀性,以及应用于不同观察条件下的图像复制效果。方法 利用均匀颜色数据集测试色貌模型颜色空间的均匀性,并通过视觉评价实验来测试2个色貌模型的图像复制效果。结果 CIECAM02的色貌空间具有更好的色差均匀性,iCAM的色貌空间具有更好的色相、明度和彩度均匀性。在不同观察条件下的图像复制中,CIECAM02有更好的表现。结论 iCAM的颜色空间适合于颜色色貌属性的计算,而CIECAM02的颜色空间更适合于颜色色差的计算,在不同观察条件下的图像复制中,CIECAM02有更稳定的表现,但并不是对所有图像都有更好的表现。     

Text binarization in color documents

This article presents a new method for the binarization of color document images. Initially, the colors of the document image are reduced to a small number using a new color reduction technique. Specifically, this technique estimates the dominant colors and then assigns the original image colors to them in order that the background and text components to become uniform. Each dominant color defines a color plane in which the connected components (CCs) are extracted. Next, in each color plane a CC filtering procedure is applied which is followed by a grouping procedure. At the end of this stage, blocks of CCs are constructed which are next redefined by obtaining the direction of connection (DOC) property for each CC. Using the DOC property, the blocks of CCs are classified as text or nontext. The identified text blocks are binarized properly using suitable binarization techniques, considering the rest of the pixels as background. The final result is a binary image which contains always black characters in white background independently of the original colors of each text block. The proposed document binarization approach can also be used for binarization of noisy color (or gray‐scale) document images. Several experiments that confirm the effectiveness of the proposed technique are presented. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 16, 262–274, 2006     

陕西凤翔木版年画色彩保护研究

目的针对陕西凤翔木版年画颜色在光的作用下变灰、变暗、变淡、褪色等现象,把凤翔木版年画抽象、主观的色彩及色彩搭配进行量化的数据转化并分类保存。方法通过分光光度计将采集的陕西凤翔木版年画颜色转化为精确的孟塞尔色卡相对应的L*a*b*色度值,进行主观比对;确定凤翔木版年画的专有色卡数据,分析凤翔木版年画的配色规律。结论建立了针对陕西凤翔木板年画的专有色卡,进行颜色数据整理及分析,总结出凤翔木版年画颜色配比量化的数据资料,从根本上解决了凤翔木版年画非物质文化遗产颜色的记录、保存、复原以及实现颜色的二次利用等问题。     

Evidence for an independent luminance channel

There is a discrepancy between several studies that have shown the human luminous-efficiency function to vary with surround color and a recent study that failed to find this dependence. Data are presented that show that this discrepancy can be explained by differences in the matching techniques. Luminous efficiency measured by direct heterochromatic brightness matching does depend on surround color, whereas luminous efficiency measured by the flicker method does not. The independence of luminous efficiency as measured by flicker is evidence for an independent luminance channel.     

Estimating illuminant color based on luminance balance of surfaces

To accomplish color constancy the illuminant color needs to be discounted from the light reflected from surfaces. Some strategies for discounting the illuminant color use statistics of luminance and chromaticity distribution in natural scenes. In this study we showed whether color constancy exploits the potential cue that was provided by the luminance balance of differently colored surfaces. In our experiments we used six colors: bright and dim red, green, and blue, as surrounding stimulus colors. In most cases, bright colors were set to be optimal colors. They were arranged among 60 hexagonal elements in close-packed structure. The center element served as the test stimulus. The observer adjusted the chromaticity of the test stimulus to obtain a perceptually achromatic surface. We used simulated black body radiations of 3000 (or 4000), 6500, and 20000 K as test illuminants. The results showed that the luminance balance of surfaces with no chromaticity shift had clear effects on the observer's achromatic setting, which was consistent with our hypothesis on estimating the scene illuminant based on optimal colors.     

Influence of luminance and resolution on the perceived quality of black-and-white images on soft displays

Abstract

The perceived quality of an image displayed on a computer monitor depends on a number of different factors that can affect viewers' preferences. Two of these are the luminance of the monitor display and the resolution of the image. The effect of luminance is of interest for applications such as on-line access of images where the computer displays used for viewing these images could have different luminance settings. A relationship between cathode-ray tube (CRT) display luminance and resolution has been shown in previous studies. It was therefore interesting to investigate whether there is a relationship between image resolution and CRT display luminance on perceived image quality. Image resolution is related to the image file size, which is an important factor for applications such as on-line access of images. This work used a CRT display to study the effect of the above-mentioned factors on the perceived quality of the displayed image. Three sets of black-and-white images, each set with a different resolution, were presented to observers at three brightness settings of the computer monitor. Results are discussed regarding the effect of monitor display luminance and image resolution on perceived image quality and the interaction between them. Evaluation of results is further extended to the influence of the different backgrounds of the images. The scene content of the images was also shown to affect the viewers' judgement.     

一种带颜色自动识别功能的卷材纠偏控制方法

为了使纠偏控制器能对卷材按颜色的方式进行纠偏,提出了使用颜色传感器TCS230代替目前纠偏控制器上广泛使用的光电传感器,采用两传感器互补交错布置的结构,构建采集系统硬件平台。基于脉宽测量法,对TCS230RGB 3种滤波片的输出值进行了采集、分析和相对比值处理,并对颜色进行了模糊识别,实现了采集系统滤波片的自动选择。实验结果表明,在卷材色彩不同的情况下,系统能够自动对滤波片进行最优选择,达到了纠偏控制器的高精度控制要求。     

敦煌传统壁画色彩网络模型构建与应用设计

目的 针对设计师在对敦煌壁画艺术色彩为题材进行设计时,往往只通过个人经验感性地提取色彩及配色,很难真正意义上还原其色彩意象等问题,提出一种敦煌壁画色彩网络模型构建及其在产品设计中的应用方法,辅助设计师进行色彩文化解码设计活动。方法 建立敦煌壁画图像库,提取图像特征色,基于图论原理,利用特征色间的共现关系,建立色彩网络模型和主辅色网络模型。运用VBA语言,基于CorelDRAW平台,开发色彩提取系统和自动配色种群生成引擎,结合色彩网络模型,辅助设计师批量生成能体现色彩意象的平面设计方案和产品开发。结论 对敦煌藻井图案创新配色及其在产品设计中的应用进行了测试,结果表明该方法可高度还原敦煌壁画的色彩意象,可作为敦煌壁画色彩创新应用的新思路。     

基于联觉实验与色彩网络的传统香薰包装设计研究

目的 香味与色彩和情绪具有紧密的联系,色彩强烈影响着香薰产品的使用感受与体验。基于联觉实验可获得香薰对应色相与感性意象,便于构建色彩网络辅助香薰产品进行色彩设计。方法 在对中国传统香薰进行深入调研的基础上,选取具有代表性的几款香薰作为研究材料。首先进行香-色联觉实验,获得香薰对应色相、情绪关系与感性意象,然后据此选取自然图片进行色彩微调,建立香-色图像数据库,最终对图片进行色彩提取并构建色彩网络模型,获得香味对应的主辅色及色彩关系,将其应用于中国传统香薰产品的配色方案与包装设计中。结论 利用嗅觉与色彩视觉之间的情绪关联作用进行联觉实验,获得的香味对应的色彩和谐自然、感性意象生动明晰,将其应用于中国传统香薰产品的设计中能够唤醒使用者的情感共鸣,带来更好的使用体验。     

Large‐Scale Noniridescent Structural Color Printing Enabled by Infiltration‐Driven Nonequilibrium Colloidal Assembly

Structural colors originating from interaction of light with intricately arranged micro‐/nanostructures have stimulated considerable interest because of their inherent photostability and energy efficiency. In particular, noniridescent structural color with wide viewing angle has been receiving increasing attention recently. However, no method is yet available for rapid and large‐scale fabrication of full‐spectrum structural color patterns with wide viewing angles. Here, infiltration‐driven nonequilibrium assembly of colloidal particles on liquid‐permeable and particle‐excluding substrates is demonstrated to direct the particles to form amorphous colloidal arrays (ACAs) within milliseconds. The infiltration‐assisted (IFAST) colloidal assembly opens new possibilities for rapid manufacture of noniridescent structural colors of ACAs and straightforward structural color mixing. Full‐spectrum noniridescent structural colors are successfully produced by mixing primary structural colors of red, blue, and yellow using a commercial office inkjet printer. Rapid fabrication of large‐scale structural color patterns with sophisticated color combination/layout by IFAST printing is realized. The IFAST technology is versatile for developing structural color patterns with wide viewing angles, as colloidal particles, inks, and substrates are flexibly designable for diverse applications.     

运动物体的阴影检测与分割

阴影检测与分割在基于视频的运动物体检测与提取中具有重要作用.为了准确检测与分割阴影,提出了基于体色向量匹配的阴影检测与分割算法.提取前景区域以后,运用亮度测试法去除亮度值高于对应背景区域的前景区域,然后预判断阴影区域,最后利用体色向量匹配提取阴影区域.另外,提出了亮度步长的方法来检测阴影中的半影.实验结果表明,算法在多数情况下对运动物体阴影检测与分割具有较好的鲁棒性,提高了检测与分割的速度.     

Tunable Resonator‐Upconverted Emission (TRUE) Color Printing and Applications in Optical Security

Lanthanide‐doped nanophosphors are promising in anti‐counterfeiting and security printing applications. These nanophosphors can be incorporated as transparent inks that fluoresce by upconverting near‐infrared illumination into visible light to allow easy verification of documents. However, these inks typically exhibit a single luminescent color, low emission efficiency, and low print resolutions. Tunable resonator‐upconverted emission (TRUE) is achieved by placing upconversion nanoparticles (UCNPs) within plasmonic nanoresonators. A range of TRUE colors are obtained from a single‐UCNP species self‐assembled within size‐tuned gap‐plasmon resonances in Al nanodisk arrays. The luminescence intensities are enhanced by two orders of magnitude through emission and absorption enhancements. The enhanced emissive and plasmonic colors are simultaneously employed to generate TRUE color prints that exhibit one appearance under ambient white light, and a multicolored luminescence appearance that is revealed under near‐infrared excitation. The printed color and luminescent images are of ultrahigh resolutions (≈50 000 dpi), and enable multiple colors from a single excitation source for increased level of security.     

Facile Synthesis of Monodispersed Polysulfide Spheres for Building Structural Colors with High Color Visibility and Broad Viewing Angle

The synthesis and assembly of monodispersed colloidal spheres are currently the subject of extensive investigation to fabricate artificial structural color materials. However, artificial structural colors from general colloidal crystals still suffer from the low color visibility and strong viewing angle dependence which seriously hinder their practical application in paints, colorimetric sensors, and color displays. Herein, monodispersed polysulfide (PSF) spheres with intrinsic high refractive index (as high as 1.858) and light‐absorbing characteristics are designed, synthesized through a facile polycondensation and crosslinking process between sodium disulfide and 1,2,3‐trichloropropane. Owing to their high monodispersity, sufficient surface charge, and good dispersion stability, the PSF spheres can be assembled into large‐scale and high‐quality 3D photonic crystals. More importantly, high structural color visibility and broad viewing angle are easily achieved because the unique features of PSF can remarkably enhance the relative reflectivity and eliminate the disturbance of scattering and background light. The results of this study provide a simple and efficient strategy to create structural colors with high color visibility, which is very important for their practical application.