Color measurement

Our color perception is characterized by subjective influences. Color measurement enables an objective description of colors. In this process, white light is sent onto a color sample and the reflected rays are measured as a percentage compared to a white standard. The physiological standard color values are first calculated from the physical measured values by standardized conversions. From these, the L*a*b* values can be determined as they are given by the CIE (Commission Internationale de l’Éclairage). While one geometry is sufficient for color pigments to describe them, several defined geometries are required for aluminum and interference pigments. These geometries (illumination and observation angles) are specified for the different measuring instruments.

Study on multi-color emotion based on fashion color in 2019

PurposeThe purpose of this paper is to derive the relationship between color schemes and emotion to serve for designers and consumers.Design/methodology/approachThe three attributes of hue, brightness and saturation of the selected sample color are analyzed, and the Semantic Differential (SD) method is used for the emotional evaluation of color schemes, and data obtained from the emotional evaluation of color schemes is analyzed by using Excel software for mean statistics and SPSS software for factor analysis and cluster analysis.FindingsFrom the results of the factor analysis, three main factors that affect the feeling of the color scheme can be extracted: “personality”, “gender” and “fashion”. Color emotions can be achieved by changing the level of color saturation and brightness, the cold and warmth of the hue and the way of color combination.Research limitations/implicationsSince it takes a long time to fill out the questionnaire, the number of valid questionnaires collected is a little less and the research data is limited. In addition, some problems are not taken into account such as geography and so on, so the results of the statistical analysis are not very precise and further research is needed.Practical implicationsIt can provide information of emotional color schemes for designers and consumers, and based on the SD method, an emotional color matching questionnaire is designed and statistical analysis is conducted to establish the relationship between emotion and color schemes.Originality/valueBased on the fashion color sample and color harmony theory, the color matching rules and color matching schemes are designed independently.

Image-Based Measurement of Structural Color using Spectral Camera

We perceive structural colors by optical phenomena such as light interference and diffraction caused by a fine structure of the object surface. One of the characteristics of structural colors is that a wavelength distribution of light changes depending on an incident angle of a light source and a viewing angle. Generally, for color evaluation and reproduction, it is required to acquire reflection characteristics of objects. Therefore, BRDF (Bidirectional Reflectance Distribution Function) is often used as a function that represents reflection characteristics depending on incident and viewing angles. In this study, we measured BRDF of structural colors based on a method to acquire image-based material reflection characteristics using a spectral camera. The measurement was performed by aligning an optical axis of a spectral camera with a structural color sample and changing an irradiation angle of a light source. Reflection characteristics were represented by using a radiance factor, which was a ratio between a spectral radiance of white material and that of structural color. From measurement results, we confirmed an angle-dependent radiance factor. Finally, based on a measured spectral radiance of a structural color sample, we spectrally reproduced the structural color using a spectral projector based on model fitting of spectral data.

Individual Differences in the Perception of Color Solutions

The color of food is important for flavor perception and food selection. The aim of the present study was to evaluate the visual color perception of liquid samples among Finnish adult consumers by their background variables. Participants (n = 205) ranked six different colored solutions just by looking according to four attributes: from most to least pleasant, healthy, sweet and sour. The color sample rated most frequently as the most pleasant was red (37%), the most healthy white (57%), the most sweet red and orange (34% both) and the most sour yellow (54%). Ratings of certain colors differed between gender, age, body mass index (BMI) and education groups. Females regarded the red color as the sweetest more often than males (p = 0.013) while overweight subjects rated the orange as the sweetest more often than normal weight subjects (p = 0.029). Personal characteristics may be associated with some differences in color associations.

Reliability of conventional shade guides in teeth color determination

Background/Aim. Color matching in prosthodontic therapy is a very important task because it influences the esthetic value of dental restorations. Visual shade matching represents the most frequently applied method in clinical practice. Instrumental measurements provide objective and quantified data in color assessment of natural teeth and restorations. In instrumental shade analysis, the goal is to achieve the smallest ?E value possible, indicating the most accurate shade match. The aim of this study was to evaluate the reliability of commercially available ceramic shade guides. Methods. VITA Easyshade spectrophotometer (VITA, Germany) was used for instrumental color determination. Utilizing this device, color samples of ten VITA Classical and ten VITA 3D - Master shade guides were analyzed. Each color sample from all shade guides was measured three times and the basic parameters of color quality were examined: ?L, ?C, ?H, ?E, ?Elc. Based on these parameters spectrophotometer marks the shade matching as good, fair or adjust. Results. After performing 1,248 measurements of ceramic color samples, frequency of evaluations adjust, fair and good were statistically significantly different between VITA Classical and VITA 3D Master shade guides (p = 0.002). There were 27.1% cases scored as adjust, 66.3% as fair and 6.7% as good. In VITA 3D - Master shade guides 30.9% cases were evaluated as adjust, 66.4% as fair and 2.7% cases as good. Conclusion. Color samples from different shade guides, produced by the same manufacturer, show variability in basic color parameters, which once again proves the lack of precision and nonuniformity of the conventional method.

Research on Reconstruction of Spectral Reflectance Based on Principal Component Analysis

Traditional color reproduction technology based on the Metamerism principle, the disadvantage is that different observer condition leads to different color appearance.To fulfill the color consistency, the spectrum reflectance of the object color sample need to be reconstructed. The principal component analysis makes use of the linear combination of a few principal components to reconstruct the spectral reflectance of sample. This paper analyzes the 31*31 matrix of Munsell spectral data by the principle component analyze method and achieves the principal component for spectrum reflectance. The numbers of principal components are identified as six by discussing the variance contribution rate. Spectral reconstruction of four Munsell testing samples makes use of first six principal components, which has met the accuracy requirements. Research shows that the reconstruction of spectral accuracy decreased when training samples and testing samples belong to the different database.