Hung-Shing Chen

Cross-cultural variation of memory colors of familiar objects

The effect of cross-regional or cross-cultural differences on color appearance ratings and memory colors of familiar objects was investigated in seven different countries/regions - Belgium, Hungary, Brazil, Colombia, Taiwan, China and Iran. In each region the familiar objects were presented on a calibrated monitor in over 100 different colors to a test panel of observers that were asked to rate the similarity of the presented object color with respect to what they thought the object looks like in reality (memory color). For each object and region the mean observer ratings were modeled by a bivariate Gaussian function. A statistical analysis showed significant (p < 0.001) differences between the region average observers and the global average observer obtained by pooling the data from all regions. However, the effect size of geographical region or culture was found to be small. In fact, the differences between the region average observers and the global average observer were found to of the same magnitude or smaller than the typical within region inter-observer variability. Thus, although statistical differences in color appearance ratings and memory between regions were found, regional impact is not likely to be of practical importance.

Proteomics analysis of altered proteins in kidney of mice with aristolochic acid nephropathy using the fluorogenic derivatization-liquid chromatography-tandem mass spectrometry method

Aristolochic acid (AA) causes interstitial renal fibrosis, called aristolochic acid nephropathy (AAN). There is no specific indicator for diagnosing AAN, so this study aimed to investigate the biomarkers for AAN using a proteomics method. The C3H/He female mice were given ad libitum AA-distilled water (0.5 mg/kg/day) and distilled water for 56 days in the AA and normal groups, respectively. The AA-induced proteins in the kidney were investigated using a proteomics study, including fluorogenic derivatization with 7-chloro-N-[2-(dimethylamino)ethyl]-2,1,3-benzoxadiazole-4-sulfonamide, followed by high-performance liquid chromatography analysis and liquid chromatography tandem mass spectrometry with a MASCOT database searching system. There were two altered proteins, thrombospondin type 1 (TSP1) and G protein-coupled receptor 87 (GPR87), in the kidney of AA-group mice on day 56. GPR87, a tumorigenesis-related protein, is reported for the first time in the current study. The renal interstitial fibrosis was certainly induced in the AA-group mice under histological examination. Based on the results of histological examination and the proteomics study, this model might be applied to AAN studies in the future. TSP1 might be a novel biomarker for AAN, and the further role of GPR87 leading to AA-induced tumorigenesis should be researched in future studies.

Spatial gamut mapping algorithms for cross-display color reproduction

— Owing to the fast developments of computer networks and color imaging technologies, there is a tendency towards remote proofing in the printing or textile industries. More cases such as cross-display color matching will occur in the future information society. The problems of color mismatching we usually find in cross-display devices have been widely discussed today. In this paper, to achieve equivalent color matching between a sRGB monitor and an Adobe RGB monitor, the spatial gamut mapping algorithm (SGMA), which introduces sigmoidal tone mapping, multi-mapping paths, and unsharp mask (USM) operation into a sRGB color-management system, is proposed. According to the designs of USM locations, this proposed SGMA can be further developed into pre-USM, post-USM, and double-USM types. Besides, two critical image characteristics, edge map and color histogram, are investigated to establish the relationship between image content and SGMA. The psychophysical experimental results show that double-USM SGMA obtains better color matching than the other spatial types.

Object-to-object color mapping by image segmentation

An object-to-object color mapping strategy depending on the image color contents is proposed. Pictorial color image is segmented into different object areas with clustered color distributions. Euclidian or Mahalanobis color distance measures, and Bayesian decision rule based on maximum likelihood principle, are introduced to the image segmentation. After the image segmentation each segmented pixels are projected onto principal component space by Hotelling transform and the color mapping s are performed for the principal components to be matched in between the individual objects of original and printed images. Experimental results in automatic color correction for inkjet prints are reported. The paper discusses on the color correction effects by PCA matching and reproduction errors in relation to the segmentation methods.

Improving museum lighting: new experiments in perception and the colour changes caused by white LED lighting

In 1941, Kruithof proposed a definition of ‘pleasant’ lighting, based on a plot of correlated color temperature (CCT) against illumination level for indoor lighting (Kruithof, 1941). A guideline for museum lighting, designed to minimize damage to museum objects from optical radiation, was published more recently (CIE, 2004). These recommendations included: removing all optical radiation below 400 nm; illuminating materials moderately or highly responsive to light below 50 lux; and illuminating materials with low sensitivity to light below 200 lux. All these recommendations were based on fluorescent and tungsten light sources. In recent years, several studies have disagreed with Kruithof’s method. Oi and Takahashi (2007) investigated preferred combinations of illuminance and color temperature for several household activities including dining, cooking, studying, and resting. They found that the preferred combinations depend on the activity, and that Kruithof’s ‘pleasant zone’ is not as appropriate when the subjects are in relatively relaxed situations. This paper describes the verification of the above observation, using novel light-emitting diode (LED) light sources. A psychophysical experiment and accelerated aging were conducted to determine the impact of CCTs and illuminance levels on visual perception in the museum, and perception zone maps (PZMs) suitable for such lighting were examined (Chen et al., 2015). The psychophysical experiment (Exp-P) was conducted to collect emotional response data under different illumination conditions defined by CCT and illuminance level. Six original paintings were reproduced, hand-painted by artists, in three styles: western oil painting, watercolor, and east Asian art. Thirty observers took part in the experiment. A Telelumen multi-LED lighting system including 16 narrow-band LEDs was used. Fifteen sets of illuminants were generated using a light replicator, including five CCTs (2700 K, 3500 K, 4000 K, 5000 K, 6500 K), and three illumination levels (50 lux, 150 lux, and 300 lux). A category judgment method was used to scale 11 semantic differential items, which fell into two categories: perceptual terms including colorful, bright, and clear; and psychological terms to describe the effect of the lighting on the painting, including warm, relax, soft, pleasant, natural, active, old, and comfort. The experiment was conducted to investigate the impact of the illumination conditions on visual perceptions in a lighting cabinet (Exp-P1) and was also performed in a museum setting (Exp-P2). The data were combined to establish the PZMs on a CCT-illuminance plane. Principle component analysis is a statistical technique that can be used to identify the number and nature of the independent components within a data set (Dunteman, 1985). It was used to investigate the relationship between the descriptive terms and the two parameters, CCTand illuminance. Semantic differential scales useful for museum lighting assessment were designed for both experiments. Eleven and ten semantic differential scales were used in Exp-P1 and Exp-P2, respectively. In addition, eight semantic scales were common to both. It was found that all emotional scales could be reduced to two dimensions, the visibility component and the warmth component, and that these were influenced by illuminance and CCT, respectively. Correspondence to: Hung-Shing Chen, Graduate Institute of ElectroOptical Engineering, National Taiwan University of Science and Technology, No.43, Sec. 4, Keelung Rd., Taipei 10607, Taiwan. Email: bridge@mail.ntust.edu.tw