Proposed light sources for illuminating in Xuan paper and silk artwork with organic and inorganic pigments by evaluating color shifts in museum

Artworks based on Xuan paper or silk and painted by organic or inorganic pigments are highly responsive to light due to their materials and manufacturing technologies. They belong to the highest level of light responsive exhibits stipulated by International Commission on Illumination (CIE) and are vulnerable to fading and discoloration caused by radiation from light sources. The choice of light sources is the key of protection for artworks. It is indispensible and urgent to choose the lowest damage light sources according to the material characteristics of artworks. In this article, long-term irradiation of typical light sources on various substrates and pigments was used as experimental method, and CIE DE2000 color difference formula was used as the evaluation index. The laws of the influence of different light sources on the color change of various materials were obtained, and the relative damage coefficients of light sources were calculated. Finally, eight kinds of light sources suitable for illuminating responsive artworks with typical material combinations were proposed. However, there are some limitations in the study, because the ancient Chinese Xuan paper and silk used as experimental objects in the experiment are yellowish. Thus, the models derived in this article are not suitable for choosing reasonable display light sources for other works of art. However, suitable light sources for different materials could be obtained by the calculation method used in this article.     

ADDITIVE COLOR MIXTURE WITH FLUORESCENT PIGMENTS AND SPECIAL ILLUMINATION

Although the artist uses subtractive color mixture when the starting point is a white surface and color mixture is accomplished by physically intermixing paints, he can use additive color mixture if he applies his paints to the canvas in small dots, creating a mosaic structure. Conventional pigments, however, lack a high enough relative brightness to synthesize white; the artist must revert to mixing white pigment to his paints to get a full range of lights and darks, just as in subtractive color mixture painting methods. By employing fluorescent pigments with special illumination, the visual artist can now obtain additive primaries of sufficient brightness to synthesize white; thus, for the first time, he can create images in his graphic media using purely additive color mixture.     

White lighting

White is a color sensation absent hue. Manufacturers describe practical light sources used for illumination as tinted warm‐white or cool‐white, but these informal designations do not seem to be based upon measured human color perceptions of white illumination. This article describes the results of a series of psychophysical experiments that more precisely measured subjective perceptions of white illumination from light sources of different correlated color temperatures (CCTs). Generally, perceptions of untinted white illumination for sources with high CCTs (above 4000 K) are associated with chromaticities that fall above the blackbody locus. In contrast, perceptions of untinted white illumination for sources with low CCTs (below 4000 K) are associated with chromaticities that lie well below the blackbody locus. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2013     

Categorical color constancy under RGB‐LED light sources

The light‐emitting diode (LED)‐based light sources have been widely applied across numerous industries and in everyday practical uses. Recently, the LED‐based light source consisting of red, green and blue LEDs with narrow spectral bands (RGB‐LED) has been a more preferred illumination source than the common white phosphor LED and other traditional broadband light sources because the RGB‐LED can create many types of illumination color. The color rendering index of the RGB‐LED, however, is considerably lower compared to the traditional broadband light sources and the multi‐band LED light source (MB‐LED), which is composed of several LEDs and can accurately simulate daylight illuminants. Considering 3 relatively narrow spectral bands of the RGB‐LED light source, the color constancy, which is referred to as the ability of the human visual system to attenuate influences of illumination color change and hold the perception of a surface color constant, may be worse under the RGB‐LED light source than under the traditional broadband light sources or under the MB‐LED. In this study, we investigated categorical color constancy using a color naming method with real Munsell color chips under illumination changes from neutral to red, green, blue, and yellow illuminations. The neutral and 4 chromatic illuminants were produced by the RGB‐LED light source. A modified use of the color constancy index, which describes a centroid shift of each color category, was introduced to evaluate the color constancy performance. The results revealed that categorical color constancy under the 4 chromatic illuminants held relatively well, except for the red, brown, orange, and yellow color categories under the blue illumination and the orange color category under the yellow illumination. Furthermore, the categorical color constancy under red and green illuminations was better than the categorical color constancy under blue and yellow illuminations. The results indicate that a color constancy mechanism in the visual system functions in color categories when the illuminant emits an insufficient spectrum to render the colors of reflecting surfaces accurately. However, it is not recommended to use the RGB‐LED light source to produce blue and yellow illuminations because of the poor color constancy.     

Designing white‐light LED lighting for the display of art: A feasibility study

When displaying art, several criteria must be balanced when designing illumination including the artist's intention, damage, energy efficiency, viewing experience and understanding, and for commercial galleries and sales. The most common lighting for art includes natural daylight and incandescent spotlights. Neither source is optimal for all criteria; thus there is considerable interest in the use of white‐light light‐emitting diode (LED) lighting. A feasibility study was conducted to address two questions. First, was it possible to design a three‐primary LED source that yielded the same color rendering as common museum lighting? Second, could one design the lighting to achieve specific color appearance attributes? Three‐primary lights using a Gaussian function were optimized matching the chromaticity of D65 and minimizing color differences for a set of acrylic dispersion paints. The optimal wavelengths depended on bandwidth. Lights were also optimized that either maximized or minimized average chroma. A set of real LEDs was selected that produced similar results when evaluated computationally. A source that increases chroma may be useful when used to illuminate works of art with high light sensitivity: very low illuminances are necessary and such a source will compensate for the reduction of colorfulness and visual clarity. A source that decreases chroma may be used to render art in similar fashion to low‐light conditions such as churches and caves. In general, white LED lighting is advantageous for art conservation because they do not emit UV and IR radiation and their visible radiation is reduced when compared with their continuous spectrum equivalent. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2011     

Simulation of colored illumination in painting using the ostwald system

With modern technology continuing to produce new and clearer pigments, it is becoming more and more important that the painter of today and tomorrow know thoroughly the colors with which he or she works. A color system is invaluable for putting those colors into context. It is not enough to be superficially acquainted with such a system; it is essential that the painter know it thoroughly. Mixing pigments to obtain other colors was adequate and necessary when the painters of the past were dealing with the limited number of pigments available to them. But now it is possible not only to make color an integral part of a painting, but also to use it to duplicate such visual effects as that resulting from the illumination on the scene.     

浅谈新彩人物画的形神表现

新彩是有别于古、粉彩的新的彩绘形式,具有发色稳定、颜色品种多、附着力强以及彩绘技法多样,艺术表现力强等工艺特色。画好新彩人物,不仅需要扎实的绘画技巧,而且需要全面的艺术修养。     

Digitally reconstructing Van Gogh's Field with Irises near Arles. Part 2: Pigment concentration maps

Colors in many paintings of great art historical value have changed over time, due to the combined effects of natural ageing, accumulated surface grime, and materials added during later conservation treatments. The physical restoration of the colors in such paintings is not possible. This article describes one part of work done to digitally restore the colors of Van Gogh's painting Field with Irises near Arles, dating from May 1888. We have used multispectral reflectance data to estimate absorption K and backscattering S parameters of Kubelka‐Munk 2‐constant theory. This was done for all 13 pigments known to have been used by Van Gogh in this painting, and based on this the concentration maps for each of these pigments were calculated. We validated the calculated concentration maps in several ways. For some pigments, we were able to predict spots on the painting where the pigment is expected to occur in unmixed form based on visual examination. For several other pigments, the concentration maps could be shown to agree with XRF data. Finally, for some other pigments the concentration maps were supported by additional evidence from microscopic examinations, remarks in Van Gogh's letters and from early color reproductions. For the 1.7 million pixels for which multispectral data is available, the average color difference between the calculated and measured spectral reflectance curves is CIEDE2000 = 1.05. This further confirms that the Kubelka‐Munk calculations are well suited to describe the variety of spectral reflectance on the painting.     

当代青绿山水瓷画审美特色

青绿山水瓷画发端于唐代,形成悠久而独特的历史发展脉络。当代青绿山水瓷画具有疏密兼备的构图形式、中西合璧的色彩形式、粗细皆具的技法形式等审美形式特色,并蕴含丰富的传统、现代与社会主义审美思想内涵。     

塑料的抗辐射着色研究

试验和研究了塑料着色用常用颜料偶氮类,酞菁类及无机颜料对PE着色后的辐照特性。发现偶氮类颜料对辐射较敏感,不宜用作辐照产品的着色,而酞菁类及无机颜料对辐射稳定,可以根据需要选择使用     

Digitally reconstructing Van Gogh's Field with Irises near Arles part 3: Determining the original colors

In earlier articles, we determined the spatial distributions and concentrations of all pigments used by Van Gogh in his painting Field with Irises near Arles. The colors of some pigments are expected to have changed over time, especially those of chrome yellow, cochineal, and eosin lake. For all pigments in this painting, we made physical paint reconstructions by following historical sources on raw materials and production processes, and we determined their optical properties. We combined this with pigment concentration maps to reconstruct the original colors of the painting digitally. When substituting the reconstruction paints into the calculations, we found that technical‐scientific data was not sufficient to resolve several issues. In those cases, discussions within the broad interdisciplinary team allowed us to make informed decisions. These issues refer to the representation of the sky area, and the original contributions of the red lake pigments to local colors. The digitally reconstructed colors of the painting show that due to discoloring of red lake pigments, the irises in the field have changed from a warm purple to purplish blue, and many pink spots in the field have turned to white. The range of yellows in the field has decreased and partly turned to dark brown. The digital reconstruction gives a better understanding of the color scheme used by Van Gogh when compared to remarks the artist made in letters when describing this painting. Also, the original color composition is seen to be aligned with color theories on which Van Gogh based his work.     

中国画线描对陶瓷绘画的影响研究

对于线描艺术,从艺术论来说:国画与陶瓷艺术同样带有深厚的民族性、区域性、审美性和历史性,二者可以说是异流同源。本文正是从中国画线描的特征及发展历程出发,来研究中国画线描对陶瓷绘画所产生的影响,意在让人们对中国画线描与陶瓷绘画有一定的认知,让人们认识国画线描与陶瓷绘画二者的联系,了解陶瓷绘画的历史、现状及未来。     

中国画线描对陶瓷绘画的影响研究

对于线描艺术,从艺术论来说:国画与陶瓷艺术同样带有深厚的民族性、区域性、审美性和历史性,二者可以说是异流同源。本文正是从中国画线描的特征及发展历程出发,来研究中国画线描对陶瓷绘画所产生的影响,意在让人们对中国画线描与陶瓷绘画有一定的认知,让人们认识国画线描与陶瓷绘画二者的联系,了解陶瓷绘画的历史、现状及未来。摘要     

Exhibiting artwork: Consider the illuminating source

This article describes the steps that should be considered for the proper illumination of artwork. In particular, our intent is to show how a different illuminating environment from one intended by the artist affects the color appearance of exhibited paintings. Using five different illuminants and several illumination levels, it is shown for eight artists' pigments that large color-appearance differences occur. This is true even after the effects of chromatic adaptation are taken into account.     

Effect of color temperature on appearance of paintings exhibited under LED lighting

Colour of light modulates the appearance of displayed artifacts in exhibition. To understand the effect of light on appearance of paintings, few studies have experimented to establish a relation between pleasantness with the correlated colour temperature (CCT) of light. However, some studies have found that CCT has no significant effect on pleasant appearance of painting. Therefore, in this article, an experiment with a qualitative (questionnaire on semantic differential scale, N = 30) approach was designed to understand the effect of CCT on appearance of paintings exhibited under LED lights. The findings from the experimental result depict that the appearance of paintings changes due to different CCTs of LEDs having the same illuminance. In addition, the result reveals that for both mediums of paintings considered in this study, in comparison to warm white LED and artificial daylight LED, cool white LED has appeared to be more pleasant having moderately warm feelings to the viewers.     

Examination, conservation and restoration of painted art

To conserve or restore painted artwork, it is necessary to appreciate the nature of the basic materials used in its creation, to be able to identify the pigments and the application media that were originally – or have subsequently been – applied and to understand the nature of gradual chemical and physical degradation that occurs within the various components of the system. With information thus gained, one can determine how best a painting may be cleaned, restored and ultimately be better preserved. This review covers the range of analytical techniques (mostly spectrographic), which have often been specifically developed to aid the identification of the wide range of inorganic colours and organic binders (or their degradation products) that may be present in each paint layer of an old masterpiece. Although an art gallery or museum strives to conserve the artefacts it displays, over time there will be varying degrees of mechanical or chemical damage. Cleaning (and, more controversially, restoration work) therefore becomes necessary and the much-improved methods now available for achieving this without associated adverse effects are reviewed.     

Understanding the influence of microbial contamination on colour alteration of pigments used in wall paintings—The case of red and yellow ochres and ultramarine blue

This article reports biocolonization assays carried out on yellow and red ochres and ultramarine blue pigments. These pigments have been most commonly used in traditional limewash of heritage buildings from southern Portugal (Alentejo) and, in the case of the yellow and red ochres, also in historical decorative wall paintings since Roman times. The research aim was to assess the potential role played by microorganisms in colour alterations observed in indoor and outdoor paint layers for conservation purposes.The assays accomplished several microorganisms previously isolated from degraded wall paintings with signs of biocontamination. The results show that apart from the clear physical stress induced in paint layers by the biometabolic activity, filamentous fungi, yeast, and bacteria are capable of inducing discoloration (in particular, the fungus Aspergillus niger). Raman analysis corroborates their active role in painting discolouration. This methodology, applied to bioprocesses, can be used as noninvasive methodology to signal microbial involvement.     

创新是传统的发展——陶瓷粉彩形式的初探

现代陶艺创作思路,给陶瓷彩绘的创新有了启发。基于对传统装饰材料和彩绘技法的深入研究与实践,充分发挥了新彩等颜色自身特有的审美特性,对单片线描和点线面描绘山水作了试验,提升了其艺术价值。     

White light emission of wide-bandgap silicon carbide: A review

White light-emitting diodes (LEDs) are the most promising alternative to the conventional lighting sources due to their high efficacy and energy saving in illumination. Silicon carbide (SiC) has a wide optical bandgap and could be tailored to emit light at different wavelengths across the entire visible spectrum by introducing different dopants. Donor and acceptor (DA) co-doped fluorescent SiC (f-SiC) is a potential candidate for replacing phosphor material in white LEDs, as it has been observed as a good wavelength converter overcoming the disadvantages of rare earth-containing phosphors, such as poor color-rendering index (CRI), short lifetime, and short degradation time. The current study attempts to present an overview on the available approaches to fabricate f-SiC for generating the white light emission and challenges in fundamental research issues to enhance quantum efficiency, color rendering performance, stability, reproducibility of color quality, and lifetime of f-SiC.