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As display technology expands the color gamut, the potential of experiencing observer metamerism is more likely with narrow bandwidth stimuli displays. Hence, it is desired to investigate whether laser-based projector would introduce observer metamerism compared to halogen-based projector. In addition, it is also desired to develop a quick method to determine an observer’s color matching function category. In this study, a two-part experiment was designed and conducted. Experiment 1 was based on color patches and Experiment 2 was based on test images. The quick method was developed in Experiment 1. Comparison to CIE Standard Observer was also conducted, and the results had suggested the CIE Standard Observer was not suitable for laser-based projection system. In Experiment 2, a prediction was made to determine the image category. With the quick method, it is much easier to achieve the realization of p

E-reading devices are becoming more and more common in our daily life, and they are used under a wide range of ambient light levels, from completely dark to extremely bright conditions. In this study, a psychophysical experiment is carried out to investigate how ambient light level affects the visual comfort of an e-reading device. Human observers compare the visual comfort of pairs of different text-background lightness combinations on a tablet device under three ambient light levels (i.e., 150, 1500, and 15,000 lx). With our previous work, the experimental results show that the trend of visual comfort interval scales below 1500 lx (i.e., Dark, 150, 300, and 1500 lx) are similar to each other but not for those under illuminance above the 1500 lx (i.e., 3000 and 15,000 lx). For the same lightness difference between text and background, the observers tend to read the text with a white background compared to a black background, especially for 3000 and 15,000 lx. Moreover, a black text on a light-gray background is the most comfortable combination under these two illuminance levels. An evaluation model is proposed based on ambient illuminance, screen parameters, and visual estimation to design an optimal viewing condition when reading on the tablet display.

This article describes the development of new models for predicting four colour appearance attributes: saturation, vividness, blackness, and whiteness. The new models were developed on the basis of experimental data accumulated in the authors' previous study, in which the four colour appearance attributes were scaled by 64 Korean and 68 British observers using the categorical judgment method. Two types of models were developed: the ellipsoid-based and the hue-based. For the former, the perceived saturation, vividness, blackness, and whiteness were modeled in the form of colour-difference formulae between the test colour and a reference colour. For the latter, blackness, whiteness, and chromaticness scales were modeled by estimating hue-dependent lightness and chroma values for the “full colour” in the framework of Adams' equation. The new models were tested using NCS data and were found to outperform some of the existing colour appearance models.

A psychophysical experiment was carried out to investigate visual comfort for reading on an iPad under various illuminance levels, ranging from 50 lx to 1200 lx, in order to see whether and how the following variables can influence the visual comfort: observer's age, gender, the illuminance of ambient lighting, and the background colour in a document layout. A panel of 21 young and 22 older Taiwanese observers participated in the study. The paired comparison method was used for data collection and analysis. The experimental results show that for all lighting conditions, young observers tended to prefer reading documents that had a moderate CIELAB lightness difference between text and background, while older observers tended to prefer reading those with an extremely large lightness difference. The results also show that female observers tended to feel less comfortable than male observers when reading documents with an extremely large lightness difference. These findings were found not to be affected by the ambient illuminance. Regarding the influence of document background colour on visual comfort, the observers tended to feel more comfortable reading documents that had a gray background than reading those with a background colour of either white or black. It was also found that the visual comfort was slightly higher for positive polarity than for negative polarity, but the difference between the two settings was insignificant. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 352–361, 2017

In a typical Euclidean three-dimensional colour space such as CIELAB, the ‘third-dimension’, such as CIELAB chroma, has long been criticized as being confusing and difficult to understand for naive observers and it had relatively poor consistency in visual assessments. As an attempt to find a promising replacement to existing ‘third-dimension’, two psychophysical experiments were conducted in this study using naive observers. In the first experiment, 24 Korean observers assessed 48 NCS colour chips in terms of bright, light-heavy, active-passive, fresh-stale, clean-dirty, clear, boring, natural-not natural, warm-cool, intense-weak, saturated, vivid-dull, distinct-indistinct, full-thin and striking. According to experimental results, ‘saturated’ and ‘vivid-dull’ were found to highly correlate with CIELAB chroma and were thus regarded as good candidates to become alternatives to existing ‘third-dimension’. In the second experiment, 40 Korean and 68 British observers assessed more than 100 samples in terms of saturation, vividness, blackness and whiteness. Thus, observers assessed 120 samples for saturation, vividness and whiteness. For blackness, 110 samples were assessed. In both experiments, the colour samples were presented in a viewing cabinet and assessed individually. Principal component analysis identified two components that were associated with CIELAB lightness and chroma. In general, there was a similarity between the visual results of the British and Korean observers. High correlation coefficients were found for the following comparisons: predicted values of Berns' depth model versus the present ‘saturation’ response; Berns' clarity versus ‘vividness’ response; Berns' vividness versus ‘blackness’ response; and CIELAB lightness versus ‘whiteness’ response. © 2016 Wiley Periodicals, Inc. Col Res Appl, 2016

A psychophysical experiment was carried out to investigate factors affecting colour preference for Taiwanese floral pattern fabrics, as a case study of object colour preference. A total of 175 test images of Taiwanese fabrics were used as the stimuli presented on a calibrated computer display. The images were generated on the basis of 5 existing Taiwanese fabrics, each manipulated into 35 images by changing the fabric colour. The 35 colours were selected to cover the most frequently used colours for existing Taiwanese fabrics. The 175 test images were assessed by 76 Taiwanese observers in terms of 9 semantic scales, including Taiwanese style/non-Taiwanese style, Japanese style/non-Japanese style, splendid/plain, traditional/modern, active/passive, warm/cool, heavy/light, like/dislike and harmonious/disharmonious. The experimental results reveal two underlying factors: “Splendidness” and “Harmony.” The like/dislike response was found to highly correlate with harmonious/disharmonious, but have poor correlation with Taiwanese style/non-Taiwanese style. The study also reveals several factors affecting colour preference for Taiwanese fabrics, including the interaction effect of colour and pattern, observer's general liking for the object, and the effect of user experience. These findings can help develop a more robust, comprehensive theory of object colour preference. © 2015 Wiley Periodicals, Inc. Col Res Appl, 2015

Two experiments were performed to investigate the effects of text-background lightness difference on visual comfort. A panel of 21 young and 20 older observers in Taiwan participated in Experiment I, using an LCD TV (with a display luminance of 551.8 cd/m2) as the presentation media. The results show that on a light background, visual comfort increases as the lightness difference gets larger and larger. On a dark background, however, the highest visual comfort value can be obtained when there is a moderate lightness difference. There seems to be little effect of age on visual comfort using the LCD TV with regard to the lightness difference. In Experiment II, 20 young and 20 older Taiwanese observers participated, using a tablet computer (with a display luminance of 397.3 cd/m2). According to the results, the larger text-background lightness difference, the higher visual comfort value for older observers. For young observers, however, the highest visual comfort value can be obtained when there is a moderate, rather than extremely high, lightness difference. These findings can help provide useful guidelines for graphic user interface design in modern e-reading devices. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 125–134, 2015

The aim of this study was to develop psychophysical models that predict the influence of pack colours on consumers' psychological responses of fruit juices, such as visually perceived expectations of freshness, quality, liking, and colour harmony. Two existing colour harmony models derived from experiments involving only uniform colour plaques were tested using the juice packaging experimental data. Both models failed to predict the visual results obtained. Nevertheless, two parameters relevant to chromatic difference and hue difference were somewhat associated with the visual results. This suggested that, among all colour harmony principles for uniform colours, only the equal-hue and the equal-chroma principles can be adopted to describe colour harmony of packaging used for juice. This has the implication that the principles of colour harmony may vary according to the context in which the colours are used. A new colour harmony model was developed for juice packaging, and a predictive model of freshness was derived. Both models adopted CIELAB colour attributes of the package colour and the fruit image colour to predict viewers' responses. Expected liking and juice quality can be predicted using the colour harmony model while expected freshness can be predicted using the predictive model of freshness. © 2013 Wiley Periodicals, Inc. Col Res Appl, 40, 157–168, 2015

Awareness of the science of appearance could help the designer to create and construct a more effective space—whether that consists of interiors, packaging, cityscapes or a plate of food. This article examines the current status of appearance science having direct application to the work of the practical designer using a vocabulary common to both disciplines. The way has been paved by the work of Shigenobu Kobayashi, of the Nippon Color and Design Research Institute, Paul Green-Armytage, a design teacher, and studies on food products and food consumption environments as well as on colour semantics studies of psychologists such as, for example, Lars Sivik and Charles Taft. The article is in two parts, appearance properties and expectations of the design and impact of the design. First, there is a brief account of the application of bipolar scales to quantify both the physical properties of the scene as well as our expectations of the scene and second, the quantification and understanding of scene impact. These techniques detail how individual elements of a designed space, such as materials, design and illumination contribute to specific desired aspects of the space. The robust model proposed provides a firm platform for active collaboration between designer and scientist in the production of comfortable and effective living and working spaces. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2012

An additive approach to predict harmony for three-colour combinations is proposed in this article. It is hypothesised that a three-colour combination can be seen as a combination of three colour pairs, each generating a harmonious/disharmonious feeling that can be quantified by a two-colour harmony model the authors previously derived; the average of these three harmony values can then determine the overall harmony. To establish whether this hypothesis was valid, two psychophysical experiments were conducted in the United Kingdom and the United States. Experiment 1 used 6545 three-colour wheels as the stimuli, presented individually on a calibrated cathode ray tube display. Under the same viewing conditions, Experiment 2 used 111 interior images as the stimuli. In each experiment, 20 British and 31 American participated as the observers. An additional test was undertaken, with 64 observers taking part, to address the issue of large sample size as encountered in Experiment 1, using 90 colour wheels selected randomly from those used in Experiment 1. The experimental results show close agreement between the observers' response and the harmony value predicted by the proposed method, with a correlation coefficient of 0.71 for the 6545 colour wheels, 0.93 for the 111 interior images and 0.88 for the additional 90 colour wheels. The results support the additive approach as a simple but robust method for predicting harmony in any three-colour combinations, which may also apply to combinations generated by any number of colours. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2011

In comparison to the great efforts made on the enhancement of image quality for tablet displays, little attention has been paid on the concept of white point. Given the increasing popularity of the light sources with chromaticities off the Planckian locus and color-tunable LED lighting, it is important to investigate human’s white perception of tablet display under different ambient lighting conditions. This study investigated the white appearance of a tablet display under 17 ambient lighting conditions, including a dark condition, seven conditions with chromaticities on the Planckian locus, and nine conditions with chromaticities off the Planckian locus, (i.e., Duv = + 0.02, −0.02, and −0.04). It was found that both the white appearance boundary defined by the fitted one-standard-deviation error ellipse and the whitest stimulus rated by the observers or identified by the bivariate Gaussian distribution were different under the various ambient lighting conditions. The optimization based on the whitest stimulus under each ambient lighting condition suggested a lower degree of chromatic adaptation under the conditions with a lower Correlated Color Temperature (CCT). For the conditions with a same CCT, a Duv of −0.02 was found to provide a higher degree of chromatic adaptation than Duv values of + 0.02 and −0.04.

The aim of this study is to investigate the impact of physical appearance attributes (in terms of color and shape) on our affective feelings of 2D and 3D objects. Twelve colors were studied, each consisting of 12 two-dimensional and 12 three-dimensional shapes. This resulted in 144 2D and 144 3D color-shape combinations. Each color-shape combination was assessed using 20 emotion scales in a viewing cabinet by a panel of observers with normal color vision. The results show that there are five underlying factors of these 20 scales, i.e., “activity,” “weight,” “heat,” “softness,” and “complexity”. The first three factors were mainly related to color and the other two were linked with shape. © 2008 Wiley Periodicals, Inc. Col Res Appl, 34, 75–83, 2009.

There are many definitions and theories about colour harmony. But no consistent rules and definitions can be determined. Some previous researches show that there are many factors that influence the colour harmony. Colour harmony is highly depends on the external factors, including the context of colour besides their colour combinations. In the current research an experiment conducted by observing two colour combinations which applied in shirt and trousers. Twenty observers involved in the experiment, consist of ten male and ten female. Each observer predict colour harmony score in 58 samples of shirt and trouser pairs, the colour combination then applied upside down. Based on the experimental results, male and female group has similar tendency in colour harmony score prediction in the same colour samples (correlation coefficient, r=0.84). Upside down colour combinations will change the impression of observer about colour harmony and yields a different value of colour harmony prediction score which indicated from correlation coefficient results of 0.53.

This study investigates harmony in two-colour combinations in order to develop a quantitative model. A total of 1431 colour pairs were used as stimuli in a psychophysical experiment for the visual assessment of harmony. These colour pairs were generated using 54 colours selected systematically from CIELAB colour space. During the experiment, observers were presented with colour pairs displayed individually against a medium gray background on a cathode ray tube monitor in a darkened room. Colour harmony was assessed for each colour pair using a 10-category scale ranging from “extremely harmonious” to “extremely disharmonious.” The experimental results showed a general pattern of two-colour harmony, from which a quantitative model was developed and principles for creating harmony were derived. This model was tested using an independent psychophysical data set and the results showed satisfactory performance for model prediction. The study also discusses critical issues including the definition of colour harmony, the relationship between harmony and pleasantness, and the relationship between harmony and order in colour. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 191–204, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20208

Eleven colour-emotion scales, warm–cool, heavy–light, modern–classical, clean–dirty, active–passive, hard–soft, harmonious–disharmonious, tense–relaxed, fresh–stale, masculine–feminine, and like–dislike, were investigated on 190 colour pairs with British and Chinese observers. Experimental results show that gender difference existed in masculine–feminine, whereas no significant cultural difference was found between British and Chinese observers. Three colour-emotion factors were identified by the method of factor analysis and were labeled “colour activity,” “colour weight,” and “colour heat.” These factors were found similar to those extracted from the single colour emotions developed in Part I. This indicates a coherent framework of colour emotion factors for single colours and two-colour combinations. An additivity relationship was found between single-colour and colour-combination emotions. This relationship predicts colour emotions for a colour pair by averaging the colour emotions of individual colours that generate the pair. However, it cannot be applied to colour preference prediction. By combining the additivity relationship with a single-colour emotion model, such as those developed in Part I, a colour-appearance-based model was established for colour-combination emotions. With this model one can predict colour emotions for a colour pair if colour-appearance attributes of the component colours in that pair are known. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 292–298, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20024

In this study three colour preference models for single colours were developed. The first model was developed on the basis of the colour emotions, clean–dirty, tense–relaxed, and heavy–light. In this model colour preference was found affected most by the emotional feeling “clean.” The second model was developed on the basis of the three colour-emotion factors identified in Part I, colour activity, colour weight, and colour heat. By combining this model with the colour-science-based formulae of these three factors, which have been developed in Part I, one can predict colour preference of a test colour from its colour-appearance attributes. The third colour preference model was directly developed from colour-appearance attributes. In this model colour preference is determined by the colour difference between a test colour and the reference colour (L*, a*, b*) = (50, −8, 30). The above approaches to modeling single-colour preference were also adopted in modeling colour preference for colour combinations. The results show that it was difficult to predict colour-combination preference by colour emotions only. This study also clarifies the relationship between colour preference and colour harmony. The results show that although colour preference is strongly correlated with colour harmony, there are still colours of which the two scales disagree with each other. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 381–389, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20047

This study investigates how a holistic color inter- val, i.e., the nondirectional color difference between a pair of colors in a CIELAB uniform color space, influences perceived color harmony. A set of 1035 test color pairs displayed on a CRT was evaluated for the degree of har- mony. These test color pairs consist of pairs combined from among the selected 46 test colors evenly distributed in color space. The subjects were asked to select their three pre- ferred colors from these 46 test colors and then to evaluate the degree of harmony of the test color combinations. The color intervals (DE* ab) of each test color combination were calculated and treated as values of an independent variable. In addition, the evaluated degrees of color harmony were considered as values of a dependent variable, in which statistical analysis confirmed the relationship: the degree of harmony is a cubic function of the color interval. Moreover, the plot of this relationship allowed us to identify four color intervals: roughly corresponding to the regions of first ambiguity, similarity, second ambiguity, and contrast in Moon and Spencer's model. However, our results indicated that Moon and Spencer's principles for classifying harmo- nious/disharmonious regions in terms of the color interval for three color attributes—lightness, chroma and hue—may be inappropriate in predicting perceived color harmony. As for the color intervals between a pair of colors considered as a function of the three attributes, the interval for light- ness may have a predominant effect on color harmony, expressed in terms of a cubic relationship. Results of the study further demonstrated that the subject's choice of colors significantly influences perceived color harmony.

The Technical Committee 1-86 of the International Commission on Illumination on “Models of colour emotion and harmony” is requesting the submission of datasets for use in developing new models of colour emotion and colour harmony. The data should be submitted to the TC Chair, Dr. Li-Chen Ou at the National Taiwan University of Science and Technology. © 2012 Wiley Periodicals, Inc. Col Res Appl, 2012