Computer Color Matching System Research Articles

The color matching design based on polynomial regression

Camouflage spots are mostly color patches of different colors. Compared with the traditional empirical color matching method, computer color matching can quickly and effectively calculate the proportion of red, yellow, and blue primary colors. In general, camouflage computer color matching in the practical application of the initial formula is not accurate and multiple color modification still cannot match. First, we measured the chroma coordinates of 98 standard swatches made of red, green, and blue coatings in different proportions by the OHSP-660 spectral reflectance tester. Then, we adopted polynomial regression algorithm by Statistical Product and Service Solutions (SPSS) to obtain the regression equation between [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]. Finally, the fitting equation is used to obtain the paint color scheme in the coordinates of [Formula: see text], [Formula: see text], and [Formula: see text] in arbitrary uniform color space, so as to realize the purpose of computer color matching. The experimental results show that the minimum color difference is 1.691 ( L* a* b* unit) the maximum color difference is 2.497, which meets the design requirements of camouflage and target color difference being no more than 3. Our work provides a theoretical basis for the further development of computer color matching system in camouflage.

Evaluation of Color Change of Heat Cured Denture Base Material Incorporated with Novel Silver Nanoparticles Submitted to Accelerated Aging

Purpose:to investigate and compare the influences of adding different concentrations of colloidal forms silver nanoparticles on color changes of heat cured acrylic resin denture base material submitted to Accelerated aging. Methods: A total of 40 disc-shaped specimens were prepared from heat cured PMMA resins with different concentration of silver nanoparticles. A double beam ultra-violet visible spectrophotometer was used to obtain diffuse reflectance data at every 5nm between 400-700nm. The results were recorded using a computer color matching system (CCM) and tabulated for the statistical analysis of the color differences (ΔE) data. Comparisons between the different studied groups were analyzed using F-test (ANOVA) and Post Hoc test (Scheffe) for pair-wise comparisons. Significance of the obtained results was judged at the significance level of α = 0.05. Results: All groups of heat-cured acrylic resin with the addition of (NAg) groups II, III and IV were showed significant (ΔE) values more than group I at initial and at stage I, II of accelerated aging records. In stage III only group IV was showed significant (ΔE) values more than group I of the same stage. Therefore, group IV was showed significantly highest mean (ΔE) value followed by group III then group II (P < 0.05) in all accelerated aging stages but group I was showed significantly lowest mean (ΔE). Conclusion: The silver nanoparticles incorporation within the acrylic denture base material can change its color. The higher incorporation of silver nanoparticles with accelerated aging, the more color difference values (ΔE) of the acrylic resin denture.

Studies on the photofading of alizarin, the main component of madder

Natural dyes have been the focus of textile industry for their environmental protection properties. However, some limitations such as poor photostability has limited their wide application, and the researches of the discoloration mechanism of fabric with natural dye are relatively limited. As one of the most important natural dye, madder has been widely used in textile field. Herein, as the main pigment of madder, alizarin was selected as the model natural dye to explore the photo-fading progress of alizarin-dyed fabrics. The photodegradation progress of alizarin was explored by UV, HPLC, HPLC-MS and Datacolor (computer color matching system). When exposed to light, alizarin could be oxidized into colorless small molecules through ·OH radical-mediated route, and finally resulting in the fading of alizarin. In addition, the influence of pre-mordant and the liquid rate has also been studied. These results provide us a good insight into the photo-fading progress of natural dyes, and our work could help to open the way to further studies aiming at improving the photostability of natural dyes or developing new photo-stable dyes.

Evaluation of a Novel Computer Color Matching System Based on the Improved Back-Propagation Neural Network Model.

To explore the feasibility of a novel computer color-matching (CCM) system based on the improved back-propagation neural network (BPNN) model by comparing it with the traditional visual method. Forty-three metal-ceramic specimens were fabricated by proportionally mixing porcelain powders. Thirty-nine specimens were randomly selected to train the BPNN model, while the remaining four specimens were used to test and calibrate the model. A CCM system based on the improved BPNN model was constructed using MATLAB software. A comparison of the novel CCM system and the traditional visual method was conducted by evaluating the color reproduction results of 10 maxillary central incisors. Metal-ceramic specimens were fabricated using two color reproduction approaches. Color distributions (L*, a*, and b*) of the target teeth and of the corresponding metal-ceramic specimens were measured using a spectroradiometer. Color differences (ΔE) and color distributions (ΔL*, Δa*, and Δb*) between the teeth and their corresponding specimens were calculated. The average ΔE value of the CCM system was 1.89 ± 0.75, which was lower than that of the visual approach (3.54 ± 1.11, p < 0.01). With respect to color distributions, substantial differences were found between the two color-matching systems, except for ΔL* (p > 0.05). The novel CCM system produced greater accuracy in color reproduction within the given color space than the traditional visual approach.

Natural dyeing with black cowpea seed coat. I. Dyeing properties of cotton and silk fabrics

A new trial to determine the dyeing properties of cotton and silk fabrics with a black cowpea seed coat as crop waste was investigated. The natural dye anthocyanins were extracted from a black cowpea seed coat in an aqueous solution and used to dye silk and cotton. The optimal conditions for colorant extraction were an aqueous solution of a dried seed coat of black cowpea in a 1:10 liquor ratio at 70 °C for 4 hours with pH of 4. The best dye-uptake of silk and cotton fabric were obtained when the pH was 3.5 and 3.0 respectively, the temperature was 80 °C for 1 hour and the liquor ratio of black cowpea was 1:20. Different colors as dusky brown, brown, faint yellow, light green, reddish brown, cyan and green could be obtained using a various kind of mordants. The depth and brightness of color tones were affected by different dyeing and mordanting pH conditions. The colors of the fabrics were examined using a computer color matching system in terms of the K/S values and CIELAB color-difference values. The dyeing was evaluated using standard light, wash and heat fastness tests. Good wash and heat fastness were obtained but the poor light fastness indicated the need for improvement to fulfill the requirement for textile applications.

Assessing the accuracy of computer color matching with a new dental porcelain shade system

In a previous study, a novel computer color matching system for dental ceramic restoration was developed, and 21 new shades were established. Theoretically, a natural tooth color can be accurately reproduced by combining 2 or 3 ceramic mixtures from the database of 21 new shades. The purpose of this study was to test the use of these shades in conjunction with the computer color matching system to determine their ability to accurately reproduce the body color of 29 shade tabs from a shade guide (VITAPAN 3D-Master). Disks of 21 reference shades were prepared with porcelain (Cerabien CZR) and polished to 1.0 mm thickness. A spectrophotometer was used to measure the reflectance values from 380 to 780 nm for each disk; the scattering coefficient and absorption coefficient were determined. By using the reflectance values and the scattering and absorption coefficients, the computer color matching program generated porcelain prescriptions incorporating proportions from the 21 reference shades to reproduce the shade tabs. Disks were fabricated from the prescriptions, polished to 1.0 mm thickness, then placed over a zirconia core plate and measured with the spectrophotometer. The color differences (ΔE*) between the shade tabs and the corresponding ceramic disks were calculated. Statistical analysis was performed with the 1-sample t test. The ΔE* values between computer color matching specimens and the target shade tabs varied from 0.5 to 1.9, with an average ΔE* of 1.3, which was significantly less than the clinically detectable ΔE* threshold of 1.6 (P<.001). The computer color matching system with the established 21 new shades is accurate and effective for reproducing tooth shades.

Developing a custom dental porcelain shade system for computer color matching

ObjectivesThis study aims to update the computer color matching method by generating a new ceramic shade system that covers the entire spectrum of natural tooth color and has an efficient design. MethodsFirst, the color map of 176 maxillary natural incisors and two commercially available and commonly used shade guide systems (Vitapan classic and 3D master) were drawn. Then, 15 shades of layered disks (NW-0: neutral white-0, A1, A2, A3, A4, B1, B4, C4, and D4, and six modifiers; white, pink, grey, blue, cervical-1 and cervical-2, Cerabien ZR) were plotted on the tooth color distribution map. Ultimately, 12 target shades were selected around the perimeter of the natural tooth color space, and nine different shades were selected within the cluster. By trial and error informed by known formulations published previously, the formulations of Cerabien ZR porcelain powders necessary to achieve these 21 target shades in thickness of 1.0mm layered on zirconia substrate were then determined and ceramic disks were fabricated. ResultsColor distribution L*–C* and a*–b* maps showed that new 21 shade system covers a slightly broader range than the natural tooth distribution, and its distribution is larger than the 3D Master shade's range. ConclusionsIn the present study, a 21 custom dental porcelain shade system was developed with a 1.0mm porcelain thickness overlying a zirconia substrate, which can be incorporated into the computer color matching system. This new shade system has homogeneity with 3D Master, and has a slightly wider color distribution than that of natural teeth.

Predicting the Degree of Toxicity of Effluent from Reactive Dye Mixtures

Environmental and public health issues associated with dyes and their effluents are problematic areas for any dyehouse. If the toxicity and color of dyeing effluent can be predicted quantitatively before dyeing, one can select suitable dyes to reduce envi ronmental pollution. This study examines the acute toxicity of dyes and associated auxiliaries in terms of EC50, and these data are used to predict the toxicity of the dyeing effluent. The prediction accuracy is satisfactory when some statistical ap proaches, such as linear and nonlinear regression, are used. Furthermore, in order to make the toxicity data much easier to understand and much more directly comparable with each other, a toxicity index has been created according to the EC50 values in this study. Incorporating the toxicity information of the dyes with a computer color matching system permits the prediction of effluent toxicity generated by colorant recipes. This should assist colorists to select a "greener" formula while satisfying basic color quality requirements and will let colorists know well ahead of time the impact of toxicity from the effluent on the environment.

ＣＣＭによるオールセラミッククラウンの色調構築 ＣＩＢＡ‐Ｑ法による検討

The layering technique which forms layered ceramics on heat-pressed dentin ingot is utilized to produce esthetic colors for all ceramic crowns. While the color of ceramic crowns has been determined based on the experience of individual dental technicians, an objective method was developed for the colordetermination using computer color matching (CCM). The purpose of the present study was to utilize a CCM system based on the CIBA-Q method for an all ceramic crown, IPS-Empress®, and evaluate the color reproducibility. Five characteristic colors for IPS-Empress® were set, and the ceramic samples composed of layering ceramic on dentin ingot were made according to the formulations prescribed by the CCM program. The colors of the ceramic samples were compared with the respective target ones. The results were as follows:1. Reflectance curves of CCM samples were very similar to that of the target ones.2. dL*was higher than dC*. Both coordinates tended to be small in case of low translucency target.3. dE between targets and CCM samples were under 2. In conclusion, the CCM system will be a great tool to reproduce esthetic colors for layered ceramics.

歯科用陶材に関する色彩学的検討 散乱係数，吸収係数の特性について

Recently, the demand for a more natural and harmonious color of porcelain-fused-to-metal restoration is on the increase due to the recent rise in esthetic values among the patients. However, the usual methodology of shade taking, color transmission, and color evaluation is not so precise. We have thus tried to resolve this problem with the aid of a computer color matching system for the purpose of reproducing the natural and harmonious color of porcelain-fused-to-metal restoration. To obtain the colorimetric and optical fundamental data of dental porcelains, we analyzed its absorption and scattering coefficients by using a spectrophotometer. It was concluded that there was a high positive correlation between the absorption and scattering coefficient to porcelain thickness in both the dentin and enamel porcelain layers. As the wavelength increased, the absorption coefficient tended to decrease and the scattering coefficient tended to increase. From this experiment, it became possible to determine the absorption and scattering coefficient of the dentin and enamel porcelain layers of any shade and thickness.