Papers by Keyword: Lightness

Abstract: In this study, the color difference thresholds of the human eye for textiles in a wide range of colors under high-illuminance conditions were examined. As the high-illuminance conditions, 2856 K-2000 lux and 6504 K-2000 lux, which are in the range of illumination conditions used in spaces that highlight products such as show windows, were used. It was observed that people cannot generally perceive color differences in textiles smaller than 4.29 ΔE*_ab. Also, the color difference threshold varied depending on the color center and lightness of the textiles observed. Color differences in red and blue colored textiles were easier to be perceived than other colored textiles, while those in yellow colored textiles were the hardest to be perceived. It was also found that people are generally better able to discriminate colors between dark textiles than between light textiles. Meanwhile, the correlated color temperature of the illuminant, that is, whether it was a warm-white (2856 K) illuminant or a cool-white (6504 K) illuminant, did not significantly affect people’s perception of color differences in textiles under high illuminance conditions.

Abstract: The authors proposed a procedure for determining parallel matchmarks in the halftone image of the rough surface. The analysis of micron-scale asperities was carried out in black and white. Relationships between coordinates of variable pixel-value sections of the microasperities under investigation were identified using the correlation analysis. The authors determined the asymmetrical distribution of various grayscales in the image of the polished surface. For that reason, the Spearman’s rank correlation coefficient was found to identify microrelief regularities that enabled to determine peaks of parallel matchmarks available on the rough surface.It is necessary to apply special filtration in order to determine periodicity of linear matchmarks which will remove point inclusions from the surface image (carbides, impurities, impregnated particles, etc.). Small inclusions in the image of the surface being analyzed are considered to be the “noise” while conducting the correlation analysis.The findings are relevant for quality control of optical surfaces. The developed program for calculating the correlation coefficient may be built into a product automatic control system used in bulk production.

Abstract: Generally, traditional low infrared coatings based on metallic pigments cannot have low lightness, low infrared emissivity and low radar reflectivity simultaneously. Herein, we used a simple and efficient method to synthesize magnetic Al/NiO composite pigments which possessed all these attributes to a degree. The results indicated that the covering area of NiO on the aluminum flake could be tuned by the addition amount of NiCO₃ and the reaction temperature of hot-flowing, both of which played a key role on the VIS/IR spectral reflectance and magnetic properties. The magnetic Al/NiO composite pigments with low lightness and low infrared emissivity could be obtained at 130 °C for 24 h in hot flowing liquid. The lightness L* could be decreased to 75.94, however the infrared emissivity (8-14 μm) was also low to 0.421. Compared with the single aluminum flakes, the Al/NiO magnetic composite pigments presented stronger magnetic properties. Therefore, the Al/NiO magnetic composite pigments offered a new choice for the pigments of multispectral stealth coating.

Abstract: The aim of this work was to determine thermal and physical properties of white-opaque sanitary glazes. Lampang pottery stone was used to replace silica (G2) and feldspar (G3) in the commercial sanitary glaze (G1). All formulations of glazes developed from Seger formula calculation and the glaze slurry was prepared by wet milling, green glazing on commercial ceramic body and firing at 1200^๐C with heating rate of 3^๐C/min by using electric kiln. Melting characteristics, specular gloss, lightness, color, and thermal expansion behavior of all sanitary glazes were investigated. As a result, the glaze G2 was a good reflecting surface with high lightness value. Linear thermal expansion difference at 500^๐C between the glaze G2 and the commercial ceramic body was-0.015%. This glaze-body fit was, therefore, under small compression and more compatible to ceramic sanitary products.

Abstract: In this study, based on CIE L^*a^*b^* uniform color space, the Color i5 measurement instrument was used to measure the color parameters of seven blood amber samples under the D₆₅ illuminant. In addition, the influences of lightness variation of the non-color background on the lightness, the color saturation and the hue of the blood amber were also investigated and discussed. The results show that the lightness of the blood amber is significantly enhanced with the increased lightness of the non-color background and the blood amber with higher transparency is more sensitive to the change of the non-color background; the color saturation of the blood amber increases gradually with the raise of the lightness of the non-color background, which means that the blood amber on the high-lightness background looks more bright-colored than the one on the low-lightness background; the red color hue angle range of blood amber turns out to be diffusing with the increase of the lightness of the non-color background, which means that a slight difference of the hue can be more easily discriminated on the high-brightness background. Thus, it can be concluded that the blood amber with higher transparency is much easier to be influenced by the non-color background; and the increase of the lightness of the non-color background can lead to higher lightness, more bright-colored saturation and diffused hue angle range of the blood amber; and the blood amber is more bright-colored and the color difference can be more easily discriminated on the background with higher lightness.

Abstract: 48 yellowish green peridots examined to test the color parameter under the neutral backgrounds whose lightness values are 10, 20, 30, 40, 50, 60, 70 and 80 by Color i5 tester, combing with the color parameter of peridots themselves, such as lightness values L*∈(50,60), chroma values C*∈(27,45), make the influence of different backgrounds on peridots’color appearence clear.With the help of two-factor analysis method, get that the F index of Row factor(standing for the lightness of peridots themselves): 16.61 which is greater than the its Fcrit index:1.40, and the F index of Column factor(standing for the lightness of backgrounds): 193.99 which is much greater than the Fcrit index, either, thus it shows that the peridots’color appearance is not only resulted by their onw lightness, but also by the backgrounds’. What is more, the influence of backgrounds is more significant; and comparing all samples’ chroma index fit line under different backgroud, find out peridot’s chroma index turning to be greater when the backgrounds’lightness increasing, and the influences are obvious during the samples with high chroma indexes. It is concluded that, for the peridots with medium lightness,the neutral backgrounds impact more on their color appearence than their own lightness do, and with the increase of backgrounds’lightness, peridots’lightness and chroma indexes will be higher.

Abstract: The computation and evaluation of color difference for images is a hot topic. In order to explore the calculation method of evaluating color difference sensation for similar images, 68 pairs of test images were made, which were made from ISO SCID 400 color images by altering their lightness and chroma respectively to cause different color difference scales, and tested by psychophysical experiment. The experiment results showed that the calculated color difference by each formula had a relation to the color difference sensation and the color difference formulae were optimized based on the experimental data.

Abstract: Through to 110 pieces purity transparent and color uniform, 3 x 5 x 7mm blue synthetic spinel made with the flame fusion method on chemical compositions and color parameter measurement the Co²⁺ content and color changes, clear the influence on Co²⁺ relationship of blue synthetic spinels’ color appearance. Through LA-ICP-MS to analysis the cause of colorant content, proof that with Co²⁺, the increase of the content of synthetic spinel will shift blue to purple tone, and C^* shows a parabola form with the drop of L^*, 700 ppm ~ 900 ppm place in peak. DL^* Î (3.55 ~ 76.94) with Co²⁺ Î (4.59 ppm ~ 1849 ppm) change the largest amount, DC^* Î (-9.99 ~ 29.32) next, DH^* Î (-20.34 ~ 4.67) compared with before two changes smallest. Co²⁺ content in 100ppm below, blue color of synthetic spinel with Co²⁺ content increased changes greatly; 500 ~ 1500 ppm, visually achieve optimal color (C^* higher); above 1500ppm, because of the Co²⁺ overmuch make the color burn cause the overall decline of transparency, the change of L^* tends to be gentle, C^* decrease obviously. Use Color i5 in standard color measurement instrument lighting source D65, measured the lightness L*, specimen Color a^* and b^*, chroma C^* and tonal angle h_o, based on the uniform color space CIE 1976 L^*a^*b^*, in lightness minimum L 9-10 specimen (processing data for standard to 9th), with the help of DE2000 benchmark for calculating formulas, the Color, the color difference train E^* by partial correlation analysis card clearly degrees of off color changes L^* has certain influence on rD_L*×D_E* = 0.996, while rD_C*×D_E*= -0.427, rD_H*×D_E* = -0.339. Conclusion, the bule color of synthetic spinel because of its Co²⁺ content changes main influencing L^* to contribute to its color appearance.

Abstract: Twenty-eight yellow-green color of uniform, high clarity and similar thickness of 5 mm × 7 mm oval faceted peridots from Jiaohe Jilin province were examined by LA-ICP-MS and Color i5 to test their chemical compositions and L^*, C^* and ho. The correlations between Fe²⁺ and color parameters were analyzed, in order to establish the influence on the color appearance of Fe²⁺. The chemical formula of the twenty-eight peridots is (Mg_1.84,Fe_0.19)_2.04[(Si_0.982,Al_0.001)_0.983O₄], which was calculated by oxygen atom. It reveals that 0.19 mol Fe²⁺ is concluded in one mol peridot, and Fe²⁺ is the colorant of peridot. Based on the CIE 1976 L^*a^*b^* uniform color space, relationships between chromaticity coordinates a^*, b^* and chromaticity C^* were analyzed by Two-way ANOVA, of which the results showing that the influence of b^* on C^* (r_b*×C*=0.996) is much more prominent than a^* on C^* (r_a*×C* = -0.383). By partial correlation analysis of the results calculated through CIE LAB color-difference formula, it can be discovered that lightness difference DL^* has a better correlation with chromatic aberration DE^* than DC^* and DH^*, whereas the significance level ρDC*×DE* > 0.05, rDH*×DE* > 0.05, it reveals that DE^* is more sensitive to DL^*. At the same time, L^* changes the most with the contributions of Fe²⁺ compared with other parameters of peridot. It is concluded that, with the help of L^*, Fe²⁺ has a further influence on the color appearance of peridot.

Abstract: This article discusses the impact of fabric structure on the heather effect of fabric woven by warp and weft with different colors. The yarns with different Lightness(L), Chroma(C) and hue angle (h) are respectively used as warp and weft, and a series of eight satin weaves are attained by strengthening weave points with interval-by-point approach, and taken as test samples. L1, C1 and h1 of each sample are measured by Optoelectronic integration color measurement instrument, and make a comparison with the theoretical values of L0, C0 and h0, which are calculated by two-color mixing principle of CIE standard Chromaticity. The result shows that: the relationship between fabric color and the percentage of color threads is in accordance with Glassman principle. However, the improvement in Lightness is slightly, the decrease in Chroma is significantly, and the change in hue angle is negligible. The more severe the degree of thread flexion is, the more obvious impact on heather effect.