Decrease In Chroma Research Articles

Laboratory model to evaluate efficacy of an experimental titanium oxide nanofibers bleaching agent.

ObjectivesThis study aimed to use a laboratory model to evaluate the efficacy of an experimental bleaching agent.Materials and MethodsThe model used human extracted molars that were treated and measured for bleaching efficacy. Teeth (n = 50) were distributed into 5 groups: Negative control (NC): immersion in water for 8 hours; Nanofibers (NFs): Experimental titanium dioxide nanofibers with stirring and light activation for 8 hours; Whitestrips (WS): Crest 3D White Glamorous White Whitestrips, 2 applications daily for 30 minutes, 14 days; 1% hydrogen peroxide (HP) standard: 1% hydrogen peroxide for 8 hours; and 30% HP standard: 30% hydrogen peroxide for 8 hours. Instrumental measurements were performed using a spectrophotometer. Results were recorded at baseline, 1-day post-bleaching, and 1-week post-bleaching. Kruskal-Wallis procedure was used to determine differences in color change. Pearson correlation was used to evaluate the relationship between visual and instrumental measurements. Tests of hypotheses were 2-sided with alpha = 0.05.ResultsThere was no significant difference in color parameters (L1, a1, b1, and shade guide units [SGU]) at baseline (p > 0.05). There was a significant difference among the groups for overall color change (ΔE*ab) and change in shade guide units (ΔSGU) at 1-day and 1-week post-bleaching (p < 0.05). The higher the HP concentration, the higher the color change as expressed in ΔSGU and ΔE*ab. The negative control exceeded the perceptibility threshold of ΔE* = 1.2 regardless of time point. NFs showed a decrease in chroma, but were not statistically different compared to the negative control.ConclusionsThe laboratory model was successful in screening an experimental bleaching agent.

LED lighting system for better color rendition space: the effect of color rendering index

ABSTRACT This study was conducted to investigate Color Rendering Index (CRI) recommendations for light emitting diode (LED) lighting in spaces needing better color rendition. Four LED spectra, that is, two spectra at Commission Internationale de l’Eclairage (CIE) Ra < 80 (79 and 76) and two spectra at CIE Ra ≥ 80 (83 and 84) were used in this study. The CIE Ra lacks accuracy in predicting perceived color quality, and the Fidelity Index and the Gamut Index were used to complement the weakness of CIE Ra. These metrics were combined to quantify the average increase or decrease in chroma. One hundred ninety-four participants evaluated retail-related tasks under different lighting conditions. The results showed that the CIE Ra had significant effects on preference, brightness perception, liveliness, and arousal. LED lights with CIE Ra < 80 received higher scores for preference, brightness perception, liveliness, and arousal than LED lights with CIE Ra ≥ 80, indicating that CIE Ra < 80 is the proper level for LED lighting in spaces needing better color rendition.

Evolution of volatile compounds and physical, chemical and sensory characteristics of Toscano PDO ham from fresh to dry-cured product

Physical and chemical changes in Toscano ham lean were evaluated according to three different seasoning time (14, 16 and 18 months). Moreover, on Semimembranosus muscle, the volatile profile at 0, 1, 3, 6, 12, 14, 16 and 18 months of seasoning was determined by SPME–GC–MS. Eventually, a quantitative-descriptive sensory evaluation was performed. Longer seasoning times led to a decrease of Chroma in Biceps femoris, and also protein and proteolysis index decreased as the seasoning time increased. A total of 97 volatile compounds (VOCs) belonging to seven chemical families (29 aldehydes, 16 esters, 14 alcohols, 13 hydrocarbons, 12 ketones, 10 acids, 2 furans and 1 nitrogenous compound) were identified. Sensory evaluation outlined the major differences between 18th months ham and the other two classes, with the former being harder and with a slight presence of off flavor and off odor. The VOCs evolution during curing was studied and a multivariate approach was performed to test the feasibility of using the VOCs profile to predict the curing stage of Toscano ham. The discriminant analysis successfully managed to separate the samples of 0–6 months from the ones of 12–18 months using 26 of the identified VOCs. Among them, pentane 2,3-dimethyl, acetophenone and 9-decenoic acid were strong discriminants for 0–6 months hams, while dodecanoic, benzeneacetaldehyde, 3-octen-2-one and pentanoic acid ethylester were linked to 12–18 months hams. Within the high maturing classes (12, 14, 16, 18 months of seasoning), the 17 discriminating compounds identified successfully allocated only 12 and 18 months samples. The main VOCs associated with the “12 months” class were nonanal, 1,5-diphenyl-3-methylthio-1,2,4-triazole and 6-methoxy 2-hexanone. The “18 months” seasoning class, instead, was identified by 1,5-diphenyl-3-methylthio-1,2,4-triazole, phenol and l,2-butoxy ethanol.

Influence of the thickness of enamel layer on overall color of composite restoration using different polychromatic composite resins

The purpose of this study was to calculate and study the color components (Chroma and Value) and translucency of resin composites at different thicknesses. Method: resin composites shade A1 were used in this study; Filtek Z350 XT 3M (FT), Harmonize Kerr (HK), and Empress Direct Ivoclar Vivadent (ED). All samples were fabricated with same dentin thickness of 2mm, while the enamel samples were prepared in two thickness; 0.5mm and 1mm. Transparency parameter evaluation was done by measuring the CIELAB parameters of each sample once against white background and once against black. ∆E was used to evaluate the change in color of composite resin at different thicknesses. One-way ANOVA and Tukey HSD test were used to analyze the descriptive statistics. Pearson correlation coefficient was used to conclude a relation between thickness and chroma; and thickness and value. Results: There was a significant difference in translucency in all composite groups at enamel thickness 0.5 and 1mm. ∆E showed significant difference when comparing group FT with ED and HK, but no significant difference when comparing groups ED and HK. As for chroma, groups ED and FT showed a decrease in chroma as thickness increased and the results were significant at (p<0.05), while groups HK showed increase in chroma but the results were insignificant. Conclusion: As thickness increases the translucency and chroma of the composite resin decreases.

Spectrophotometric and computerized evaluation of tooth bleaching employing 10 different home-bleaching procedures: In-vitro study.

Objective:The aim of this in-vitro study was to evaluate the efficacy of bleaching products, determine the applicability and validation of the measurement methods.Materials and Methods:Freshly extracted 110 human incisor teeth were stained with whole blood and hemolysate solution prior to the application of 10 different home-bleaching products. Spectrophotometric measurements of the tooth shades were performed for each specimen before and after bleaching at the 1st, 3rd, 7th, and 14 days. Differences in lightness (Δl), chroma (Δc), hue (Δh) values and shade changes were measured to evaluate process. Computerized digital imaging analyses to determine the color changes were performed with Photoshop CS4 software (Adobe, San Jose, CA, USA). Statistical analyses were performed with analysis of variance, Scheffe and Tukey tests.Results:In all of the test groups regardless of the material used, a significant increase in lightness and hue, and decrease of chroma were observed, as compared to the control group. After recommended bleaching applications, Δl and Δh values respectively increased in group Zaris White and Brite (ZWB) and group Pola Night and Δc values showed significant decrease in groups ZWB and Rembrandt REM3 (P < 0.05). At the end of the procedure both spectrophotometric and digital imaging analysis showed ZWB was the most effective product among the others while Yotuel and Happy Smile were the least (P < 0.05).Conclusions:Home-bleaching systems showed slower but almost permanent bleaching effect likewise office-based methods. Both software and spectrophotometric analyses have advantages such as evaluating the results objectively and numerically, also treatment outcomes could be preserved.

Pearl netting affects postharvest fruit quality in ‘Vergasa’ sweet pepper via light environment manipulation

Red sweet pepper (Capsicum annuum L. cv. Vergasa) was grown under Pearl or black (control) nettings with 35% shading to compare their effects on postharvest fruit quality. Fully colored fruits were harvested four times from October to December, and after each harvest they were stored at 7°C for 16 days, followed by 20°C for 3 days. Compared with black netting, the Pearl netting significantly reduced water loss, decay incidence and titratable acidity, and increased fruit firmness, elasticity, ascorbic acid level and antioxidant activity, but did not change the external quality, except for a decrease in chroma. The effects of the Pearl netting were most pronounced on late-season-harvested fruits. Significant interactions were obtained between the shade netting type and harvest date. Analysis of correlations among the quality traits indicated that increased antioxidant activity and ascorbic acid content were tightly associated with the postharvest fruit quality attributes affected by the Pearl netting. Comparison between climatic parameters under the two netting treatments revealed no significant difference in air temperature and humidity, but the Pearl netting increased not only transmittance of long-waveband light but also light intensity within plant canopy. The findings suggest that the Pearl netting is more effective in maintaining postharvest sweet pepper fruit quality than the traditional black netting, especially at late-season harvests. The effects of the Pearl netting can be related to alteration of antioxidant levels induced by the pre-harvest light environment manipulation.

The Impact of Fabric Structure on the Heather Effect of Fabric Woven by Warp and Weft with Different Colors

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.

Do Male Pied Flycatchers (Ficedula hypoleuca) Adjust Their Feeding Effort According to Egg Colour?

The colour of blue-green bird eggs has been hypothesized to signal female quality to attending males, who may adjust their level of investment in the brood accordingly. The hypothesis has gained support in studies of Spanish pied flycatchers Ficedula hypoleuca. We performed a cross-fostering experiment in a Norwegian population of pied flycatchers to provide an independent test of the sexually selected egg colour hypothesis in this species. Egg colour was not significantly correlated with estimates of female quality (clutch size, average egg volume, first egg laying date and feeding rate). There was a significant decrease in chroma and increase in brightness and egg volume during the laying sequence, with some marked differences between six-egg and seven-egg clutches that might reflect differences in female quality. However, we found no significant influence of egg colour (foster or original clutch) on male feeding rate or offspring viability (hatching success, average mass and fledging success) and no significant difference in feeding rate for males with six-egg and seven-egg foster or original clutches. We conclude that Norwegian male pied flycatchers do not use egg colour as a cue to female quality, thus questioning the generality of previous support for the sexually selected egg colour hypothesis from this species.

Angular Variations of Color in Turbid Media &amp;#x2013; the Influence of Bulk Scattering on Goniochromism in Paper

The angular variations of color of a set of paper samples are experimentally assessed using goniophotometric measurements. The corresponding simulations are done using a radiative transfer based simulation tool, thus considering only the contribution of bulk scattering to the reflectance. It is seen that measurements and simulations agree and display the same characteristics, with the lightness increasing and the chroma decreasing as the observation polar angle increases. The decrease in chroma is larger the more dye the paper contains. Based on previous results about anisotropic reflectance from turbid media these findings are explained. The relative reflectance in large polar angles of wavelengths with strong absorption is higher than that of wavelengths with low absorption. This leads to a loss of chroma and color information in these angles. The increase in lightness is a result of the anisotropy affecting all wavelengths equally, which is the case for transmitting media and obliquely incident illumination. The only case with no color variations of this kind is when a nonabsorbing, non-transmitting medium is illuminated diffusely. The measured and simulated color differences are clearly large, and it is an open issue how angle resolved color should be handled in standard color calculations.

On the relations between color, gloss, and surface texture in injection‐molded plastics

AbstractThe relation between color and gloss of injection‐molded plastic specimens was evaluated by means of a 45°/0° geometry spectrophotometer and a glossmeter. The specimens were plaques having one smooth, glossy field and one rougher, textured region made of two different polymeric materials (acrylonitrile‐butadiene‐styrene and polypropylene) in a range of colors. A significant influence of the lightness L* of the specimens on the measured gloss of the textured field, with a low gloss appearance, was found. This can probably be attributed to a contribution from bulk scattering, which is linked to the reflectance from within the specimen. The influence of texture on the measured color of the plaques was assessed by evaluating the color difference between the smooth field and the more textured area on the specimens. When the surface was textured, the color changed; in general it became lighter and less saturated. The magnitude of the change depended on the color of the material. The darker the material was, the larger was the increase in lightness L* as the surface became rougher. The shift in chroma C* was determined not only by the saturation but also by the lightness of the specimens. Darker specimens exhibited a larger decrease in chroma when the surface was textured. The change in the measured color caused by increasing the surface roughness could be predicted in a satisfactory manner using a model developed for xerographic printing paper. © 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 291–298, 2009

Analysis of gamut mapping algorithms from the viewpoint of color name matching

Abstract—The validity of color name matching in analyzing gamut mapping algorithms is described in this paper. The performances of three types of gamut mapping algorithms (cusp scaling, clipping, and categorical weighting) are evaluated in a psychophysical experiment from the viewpoint of color name matching. Based on this evaluation, we have found that cusp‐scaling algorithm is capable of controlling lightness reasonably well, compensating for a decrease in chroma caused by the difference in the size of device gamut between a source and a destination device. Ranking of reproducible performance by the three gamut mapping algorithms in the psychophysical experiment is arrived at on the basis of color name matching.

In vitro color stability of double-layer veneers after accelerated aging

Statement of problem. Porcelain laminates made from thin alumina shells veneered with feldspathic porcelain could be a promising alternative to conventional veneers. Long-term shade stability is critical for esthetics. Purpose. This study compared changes in CIE L*a*b* color coordinates of simulated veneers made from aluminum oxide core material veneered with feldspathic porcelain after 300 hours of accelerated photothermal aging (weathering). Material and methods. Fifteen aluminum oxide disks (Procera) were divided into 3 groups. Each of the 5 disks was veneered with All-Ceram porcelain of the Vita shades A1 and B4, respectively. Five disks remained unfinished as controls. The disks were bonded to composite substrates simulating stained teeth. The color of the specimens was measured with a colorimeter. All specimens were subjected to 300 hours of accelerated aging under light exposure and thermocycling. Color measurements were repeated, and the data were statistically evaluated with multiple paired t tests. Results. Color changes in the test groups involved an increase in lightness and a decrease in chroma. The calculated total color differences were not statistically significant compared with a level of 3 ΔE units. Conclusion. This simulation of double-layer veneers appears to demonstrate acceptable color stability for this type of restoration. Clinical research is necessary to substantiate these in vitro findings. (J Prosthet Dent 2001;85:551-7.)

着色物体の「深み感」と「色の濃さ」および「黒み」の関係

In a previous paper, we carried out a subjective evaluation by paired comparison to examine the contribution of three color attributes to “Fukami”, and then to form the “Fukami” scale. We found that “Fukami” is related to the decrease in value and chroma, and also that it depends on the difference in hue. After the evaluation, it was reported that “Fukami” was depended on the degree of color depth sensation. We took notice of this fact.First, we studied the relationship between “Fukami” and the color depth sensation. For both sensations, there were many similar tendencies for the change in value and the difference in hue. But for low values and chromatic color areas, the contribution of the chroma to each sensation was opposite, therefore we could not find a good relation between them.Next, we defined the “Kuromi” sensation based on the color depth sensation and examined the relation to “Fukami”. We verified that the “Kuromi” (KL*) increased with the increase in color depth sensation and the decrease in chroma. The fundamental relation model between“Fukami” and “ Kuromi” is described as follows.Fukami=Kh (KL*-δh) [δh≤KL*≤10]Kh and δh are calculated from the hue (dH5p). This equation is very simple and explicates the effect of “Kuromi” in relation to “Fukami”. But, the equation has the tendency to shift the “Fukami” peak from hue GY to hue BG, of equal value, with the decrease in chroma. So, we consider it necessary to improve the equation for practical use.

Factors Affecting Anthocyanin Accumulation in Solanum tuberosum

The color of red potatoes is due to an accumulation of anthocyanins in periderm tissues. The objective of this study was to examine the effect of several factors on tuber redness. Using the red tuber-producing S. tuberosum ssp. tuberosum cultivar Norland, we observed that chroma (intensity of redness) and anthocyanin content of greenhouse-grown tubers decreased as tuber weight increased. There was a slight or no increase in hue (tint). We used HPLC to determine that pelargonidin and peonidin are the major anthocyanidins (aglycones of anthocyanins) in tuber periderm. The ratio of pelargonidin to peonidin increased as tuber weight increased up to 25 g fresh weight. The decrease in chroma was not due to an increase in cell sap pH; we observed a decrease in cellular pH as tuber weight increased. Controlled-atmosphere storage had no effect on tuber chroma or anthocyanin content compared to air storage. Methyl jasmonate, sucrose, or light treatment did not increase anthocyanin accumulation. Tubers exposed to light had less anthocyanin than those kept in the dark. We are examining the developmental expression of anthocyanin biosynthetic genes, as well as the effect of maize transcription factors on anthocyanin synthesis, in tuber periderm.

Observation of the effects of photochemical smog on the upper respiratory systems in junior high school students (author's transl)

In order to investigate the influence of photochemical smog upon the upper respiratory systems of humans, long-term examinations were made on junior high school students in urban districts. Objective methods were devised for better description of the color of the mucosa as well as for evaluating olfactory functions. Examinations were made on the day of photochemi- cal smog and the results were compared with those obtained before and after the smog season. The results were as follows; 1) On inspection of the nose and throat, no specific findings were noticed on the day of photo- chemical smog. 2) Color analysis of the nasal mucosa on the day of photochemical smog showed that there was a tendency toward decrease in chroma. 3) No abnormalities were found in olfactory function on the day of photochemical smog.