A Colour Design Tool Based on Empirical Studies

A colour design tool targeted at both unskilled consumers and professional designers is currently under development, on the basis of psychophysical studies into semantic associations of colour, the cultural influences and colour harmony. From experimental results for single-colour associations, 3 underlying factors were identified: “warm-cool”, “heavy-light” and “active-passive”, which were found to agree well with those identified by earlier research. For colour-combination associations, an “additive property” of colour association was discovered: the semantic score of a colour combination can be determined by averaging semantic scores of each constituent colour in that combination. According to the experimental results, there were 4 general patterns of colour harmony: similarity in hue and chroma, difference in lightness, high lightness and the hue effects. While the proposed colour design tool is still in its development stage and has a number of shortcomings, the system is believed to provide practical assistance and support not only for unskilled users but also for designers. Keywords: colour design; colour harmony; colour association; cross-cultural study; e-shopping; colour decision-making; design process; psychophysical method</p

Influence of viewing conditions on cross-media color matching

We investigated observer metamerism under a variety of viewing conditions, in a set of color-matching experiments using displays and printed color samples under specific light sources. A selection was made of light sources with different illuminances, spectral power distributions, and correlated color temperatures, as well as displays with different sets of primaries. A panel of 157 observers with normal color vision and ages between 20 and 59 years old performed 5465 visual color matches around 9 different color centers. The results from the simulated and real experiments were quite different. Specifically, the mean color difference from the mean changed with experimental viewing conditions, ranging from 0.73 to 1.64 CIELAB units (average 0.99 CIELAB units) in simulated experiments, and from 3.12 to 4.03 CIELAB units (average 3.55 CIELAB units) in real experiments. In real experiments, observers’ variability reduced for light sources with high illuminance and high correlated color temperature. Spectral power distributions affected observer metamerism, but the role played by the primaries of the two displays employed was unclear.National Natural Science Foundation of China (NNSFC), 61675029. Ministry of Economy and Competitiveness of the Government of Spain, co-financed by the European Regional Development Fund (ERDF) of the European Union, research project FIS2016-80983-P

Developing a digital archive system for imperial Chinese robe in the Qing Dynasty

The digital archive of cultural heritage provides new opportunities for the protection of the cultural heritage and the development of online museums. One of the essential requirements for the digitization is to achieve accurate color reproduction. Taking the Imperial Chinese robes in the Qing Dynasty as an example, this study aims to develop a digital achieve system to digitize the robes using a high-end imaging system and accurately reproduce their color properties on a display. Currently, there has been very limited study focused on the color reproduction of silk fabrics or other textile materials. The conventional color management process using a traditional color chart, however, may not be suitable for the reproduction of silk fabrics because they have very high gloss. To address this difficulty, a unique “Qianlong Palette” color chart, consisting of 210 silk fabric samples, has been specifically produced for optimizing the color reproduction of silk fabrics and a color image reproduction system has been developed for the digitization and archiving of the clothing fabric for the royal court. Color characterization models using both the “Qianlong Palette” color chart and the traditional color chart, and different mapping methods, are compared and the model with highest accuracy used in a self-programmed interface for automatically processing textile images in the future. Finally, the digital archive system has been validated using six garments of silk fabric relics. The color differences after the color image reproduction are all less than 3.00ΔE*ab, indicating acceptable color reproduction of the system. The images after color reproduction have also been evaluated subjectively by experts from the museum and the results are considered satisfactory. Our results show that the newly designed “Qianlong Palette” color chart exhibits superior performance over the conventional color chart in effectively predicting the color of the silk fabrics. The self-programmed graphical user interface for image color management can serve as a powerful tool to truly reproduce the color of various silk fabric relics in museums in the future and digitally archive those valuable cultural relics for different uses

A Neutral White Locus

status: publishe

Cheng Li, Evaluation of LED Sources Based on Colour Appearance Data ABSTRACT Evaluation of LED Sources Based on Colour Appearance Data

The current CIE colour rendering index (CRI) has been widely used to test the quality of light sources over 30 years. However, this method is outdated and problematic, especially for evaluating white light emitting diode (LED) sources. A psychophysical experiment was conducted to evaluate the quality of three D65 simulators. The results were also compared with the CRI and the other method, known as CQS. Furthermore, both indices were modified based on CAM02-UCS, and some improvements were found

Spectral Optimization of White LED Based on Mesopic Luminance and Color Gamut Volume for Dim Lighting Conditions

The study aims to propose an approach of white LED spectral optimization based on mesopic luminance and color gamut volume for dim lighting conditions. Three optimal white LED spectra with relatively higher mesopic luminance and color gamut volume, the highest mesopic luminance, and the largest gamut volume are recommended for reducing energy consumption and enhancing color perception and recognition of human eyes. The theoretical simulation shows that the spectra with higher correlated color temperatures (CCT) and S/P-ratio increase the mesopic luminance and also extend the range of color gamut with the decreasing of lighting level. An evaluation model is developed to faster predict mesopic luminance, color gamut volume, and S/P ratio for lighting applications

The Effectiveness of Colour Appearance Attributes for Enhancing Image Preference and Naturalness

Investigation of image quality on preference and naturalness using 1- dimensional and 2- dimensional colour attributes was performed. Each colour attribute varied in two directions, and each direction had two levels, i.e. large and small. In the present study, paired comparison was employed for image preference and categorical judgement for image naturalness assessment. The aim was to evaluate the performance and effectiveness of 1-dimensional and 2-dimensional colour attributes on image quality. Furthermore, cultural difference, the relationship between image preference and naturalness, the difference between memory colours in colour patches and digital images were examined. The experimental results revealed that the effectiveness of colour attributes on image quality vary with image content