Color Research and Application最新文献

We present the results of a series of three brightness-matching experiments which include a key refinement in this established psychophysical method. Constraining the chroma difference between pairs of stimuli matched in brightness allows us to use a novel calculus-based approach to building a model of the brightness of chromatic visual stimuli and the Helmholtz-Kohlrausch effect. The proposed models, compatible with the CIECAM16 color appearance model and CIELAB color space, are compared to other models of the Helmholtz-Kohlrausch effect on these data and other past brightness-matching studies. The proposed CIECAM16-based model demonstrates the overall best performance on predicting the Helmholtz-Kohlrausch effect in four newer data sets but overpredicts the weaker effect reported in three older data sets. The potential experimental factors in this divide between new and old studies are also discussed.

Tristimulus values and chromaticities, which are derived using the color matching functions (CMFs), are commonly used for color characterization, calibration, and specifications, with the stimuli having the same values believed to have the same color appearance (i.e., metameric match). Many studies, however, found that the stimuli having the same tristimulus values do not appear the same (known as metameric failure) due to the failure of CMFs in accurately characterizing the color matching mechanisms. Most past work investigated the performance of different CMFs through color matching experiments, with a smaller chromaticity or calculated color difference between the reference and test stimuli suggesting a better performance. Such differences, however, may not accurately characterize the performance of the CMFs, since the color spaces or chromaticity diagrams may not be uniform, in terms of the threshold of noticeable color difference. In this study, the human observers evaluated the perceived color difference between pairs of stimuli, which were calibrated to have the same tristimulus values calculated using the CIE 1931 2° CMFs, with two sizes of field of view (FOV). The results clearly suggested that the stimuli having the same tristimulus values may not always appear the same, which depended on the primaries and the FOV. More importantly, the results clearly suggested that the chromaticity differences from color matching experiments may overestimate the metameric failure, especially when the color differences were small.

New photoluminescent materials have numerous possibilities in many different areas from technological applications to contemporary glass art and design, encouraging the development of new forms and products. Glass luminescent materials, known for their exceptional durability and recyclability, position glass as an ideal solution for fostering a more sustainable future. In recent years, white luminescence in glass and ceramics has been the subject of several investigations about its possible application in white light-emitting diodes (WLED). Color coordinates and CIE chromaticity diagrams serve as valuable tools to represent and define the range of luminescent colors achievable in a particular composition. These aid in understanding wheter a composition can be used to produce white luminescence or various other colors.  In this study, a soda-lime silicate glass composition was doped with a mixture of different lanthanide oxides to increase the luminescence color palette. The same glass sample can also present different colors by changing the excitation light, allowing higher tunability of luminescent colors. It was effectively demonstrated the extensive spectrum of colors produced, which was represented through luminescence color coordinates for all synthesized glasses. Moreover, the possibility of detecting if an excited state process is occurring was studied by calculating the lanthanides factors and comparing them with those used in the glass synthesis. Nevertheless, it is shown that the energy transfer process has to be significant to influence the color coordinates and the calculation of the factors.

Studies on the color category PURPLE yielded inconsistent category boundaries, focal colors, and color-emotion associations. In French, there are at least three color terms referring to the shades of purple, potentially weighing on these inconsistencies. Thus, we tested the semantic breadth and richness in semantic meaning of violet (basic term), lilas (non-basic), and pourpre (non-basic). We collected free associations in 274 French speakers from Algeria, France, and Switzerland, yielding 2079 responses, of which 436 were discrete and 275 were unique. Frequency analyses and semantic coding supported the basicness status of violet in French, within a hierarchically structured semantic system. Moreover, the meaning of the three terms was not synonymous. Violet had the most abstract meaning. Lilas had the narrowest meaning, mainly referring to Natural Entities. Pourpre seemed close to RED. We found no differences between the countries. Future studies should extend this approach to other languages and other color terms.

Previous studies have offered multiple explanations for the causality of color preference but no consensus has been reached. In this study, we propose an alternative explanation that the memory colors of familiar objects, especially food colors of humans can induce color preferences. We conducted two experiments. In Experiment 1, the memory color experiment, we asked participants to rate the similarity between presented color samples and memory colors of five familiar fruits and vegetables in Japan; we then calculated the location of the colors in the CIELAB color space that looked most similar to the remembered objects using the bivariate Gaussian function. In Experiment 2, the color preference experiment, color variations were created based on the memory colors obtained from Experiment 1. A different group of participants rated their preference for each color variation, then we applied regression analysis to these ratings. We observed two types of regressions between preference ratings and distance to memory colors: (1) for colors from red to green that represent the food colors for primates, color preference increased when the color was closer to the memory colors of the fruits and vegetables found in Experiment 1; and (2) for blue and purple colors, colors were preferred when they became bluer. We suggest that the evolutionarily acquired mechanism of color preference derives crucial cues from our ecological environment. Therefore, the mechanism produces the same color preference trend among people who grow up in similar environments, for example, environments containing the same fruits.

This study examined whether people's ability to recognize facial expressions is affected by manipulating the color of their lips or eyes. Participants comprised 100 Chinese adolescents (mean age = 13.79 years, SD = 1.06). The stimuli consisted of happy, neutral, and sad facial expressions, which were manipulated to have different lip or eye colors. Participants reacted to the images by indicating their perceived emotion. Performance speed and accuracy were assessed during the experiment. Results indicated that for happy and neutral expressions, the use of color significantly reduced reaction times, while the accuracy remained unchanged. Conversely, for sad expressions, reaction time was not affected by color, but all color categories exhibited reduced accuracy.

In the paper “The non-Riemannian nature of perceptual color space,” the authors analyze the data of visual experiments conducted using triad of CIE $�L^{*}$ achromatic stimuli. The statistical analysis of their results leads them to claim that the $�L^{*}$ axis cannot be endowed with a Riemannian metric coherent with observers' responses. In this communication we provide a mathematical analysis which, in our opinion, refutes the main claim of the quoted paper. Furthermore, we raise questions on the soundness of using an achromatic perceptual coordinate to describe non-chromatic perception. We inform about an alternative in which achromaticity emerges from the very act of observing colors (Provenzi E. SIAM J Imag Sci, 15(4):1944–1976, 2022; Berthier M, Provenzi E. Proc R Soc A, 478(2258):20210508, 2022).

Color significantly shapes our perceptions of the world, and extensive scientific research has explored various aspects of color, including color linguistics, aesthetics, color and marketing, color therapy, and color psychology. Notably, there has been an increasing interest in understanding the psychological domain of color in recent years. However, limited scholarly attention has been given to studying the changes in color representations and emotions over the decades. To address this gap, we utilized word embedding models of Google Books Ngrams corpus to examine the most strongly associated entities and traits with colors and their evolution in color emotions over 200 years. Analyzing three emotional dimensions—pleasure, arousal, and dominance (PAD), we found that red, green, white, black, orange, purple, brown, and pink were related to the exuberant type (+P + A + D) in PAD emotional space. In contrast, blue was linked to the relaxed type (+P−A + D), and yellow constituted the anxious type (−P + A−D). Among all basic English color terms, the emotion-driven perceptions associated with white, brown, and pink have significantly changed over time.

In the process of cataloging the estate of modernist artist Almada Negreiros, many preparatory drawings for several of the author's public artworks are currently being identified. The volume and complexity of his prolific work imply that sometimes it is hard to connect specific documents and artworks of research and preparation to their respective final works. Recently, one particular drawing proved to be the key for understanding several other documents, simultaneously contributing to clarify the artist's methodology when preparing for the large-scale stained glass behind the altar of Igreja de Nossa Senhora de Fátima. This article presents these new advances.