The Experts below are selected from a list of 822 Experts worldwide ranked by ideXlab platform
Hyeongcheol Yang - One of the best experts on this subject based on the ideXlab platform.
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metameric effect between dental porcelain and porcelain repairing resin composite
Dental Materials, 2007Co-Authors: Sanghoon Rhee, Hyeongcheol YangAbstract:Abstract Objectives The objectives were to evaluate the metameric color and hue angle (°) changes between dental porcelain and porcelain repairing resin composites. Methods Color of three shades (A2, A3, A3.5) of one brand of dental porcelain and three original shades (A2, A3, A3.5) and three combinations (A2–A3, A3–3.5, A2–A3.5) of three brands of porcelain repairing resin composites (ABT, FSP, TCR) were measured relative to the three standard illuminants (D65, A and F2). Specimen was 2 mm in thickness, and 1 mm of each shade was layered to make combined shades. Color differences ( Δ E a b * ) between each shade of dental porcelain and repairing resin composites relative to the three illuminants were calculated, and the ratios of color difference (modified Metamerism index) by the change of illuminant were calculated. The ratios of hue angle changes were also compared. Results Differences in modified Metamerism index and the ratio of hue angle changes were influenced by the porcelain shade, brand of resin composites and shade of resin composites. In all three brands of resin composites, A3.5 shade showed the smallest values in modified Metamerism index regardless of the shade of porcelain. The average ratio of hue angle changes between each porcelain shade and all the shades of each resin composites showed similar trend when illuminant was changed from D65 to F2. Significance Metameric effect between dental porcelain and repairing resin composites varied depending on the shade of porcelain, brand of resin composite and the illuminant. Therefore, shade matching between porcelain and repairing resin composite should be performed carefully. This study confirmed that shades should be matched under the light corresponding to that of use.
Sanghoon Rhee - One of the best experts on this subject based on the ideXlab platform.
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metameric effect between dental porcelain and porcelain repairing resin composite
Dental Materials, 2007Co-Authors: Sanghoon Rhee, Hyeongcheol YangAbstract:Abstract Objectives The objectives were to evaluate the metameric color and hue angle (°) changes between dental porcelain and porcelain repairing resin composites. Methods Color of three shades (A2, A3, A3.5) of one brand of dental porcelain and three original shades (A2, A3, A3.5) and three combinations (A2–A3, A3–3.5, A2–A3.5) of three brands of porcelain repairing resin composites (ABT, FSP, TCR) were measured relative to the three standard illuminants (D65, A and F2). Specimen was 2 mm in thickness, and 1 mm of each shade was layered to make combined shades. Color differences ( Δ E a b * ) between each shade of dental porcelain and repairing resin composites relative to the three illuminants were calculated, and the ratios of color difference (modified Metamerism index) by the change of illuminant were calculated. The ratios of hue angle changes were also compared. Results Differences in modified Metamerism index and the ratio of hue angle changes were influenced by the porcelain shade, brand of resin composites and shade of resin composites. In all three brands of resin composites, A3.5 shade showed the smallest values in modified Metamerism index regardless of the shade of porcelain. The average ratio of hue angle changes between each porcelain shade and all the shades of each resin composites showed similar trend when illuminant was changed from D65 to F2. Significance Metameric effect between dental porcelain and repairing resin composites varied depending on the shade of porcelain, brand of resin composite and the illuminant. Therefore, shade matching between porcelain and repairing resin composite should be performed carefully. This study confirmed that shades should be matched under the light corresponding to that of use.
Andrew C Oates - One of the best experts on this subject based on the ideXlab platform.
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the segmentation clock inherited trait or universal design principle
Current Opinion in Genetics & Development, 2012Co-Authors: David L Richmond, Andrew C OatesAbstract:Metamerism is a widespread feature of multicellular body plans; however, our understanding of the underlying mechanisms that generate these patterns is currently based on only a few model organisms. In particular, vertebrate embryos use a segmentation clock to rhythmically and sequentially add segments in concert with posterior elongation of their body. Recent evidence of a segmentation clock acting in arthropods indicates that this mechanism may be a widely used strategy for generating serial anatomy in animals. Whether this is due to homology or convergence is not yet known, but the recent discovery of an oscillatory process associated with the production of sequential root primordia in plants suggests that a segmentation clock is a fundamental patterning principle in growing tissues, independent of ancestry. In this review, we consider the principles of the segmentation clock that may be conserved across the animal and plant kingdoms, and discuss opportunities for cross-fertilization between these active fields of research.
Leite, Frederico Nogueira - One of the best experts on this subject based on the ideXlab platform.
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Calibração de dispositivos a cores utilizando uma camera digital
2011Co-Authors: Leite, Frederico NogueiraAbstract:Em ambientes que possuem uma grande quantidade de monitores e impressoras, onde a coerência de representação de cor é requerida, a calibração de dispositivo é fundamental. Calibração é em geral executada utilizando ferramentas colorimétricas, usualmente requerendo dispositivos sofisticados como colorímetros ou espectrofotômetros. Nesta tese propomos um método mais barato de executar a calibração de maneira não colorimétrica utilizando uma câmera digital como substituta do colorímetro. Para isto, utilizamos a câmera como um simples dispositivo de mapeamento. A calibração é feita a partir de referencias, isto é, um dispositivo é calibrado tendo como referência outro dispositivo. Desenvolvemos um método de evitar ou minimizar a adaptação da câmera e a lidar com Metamerismo. Ambos podem prejudicar a medição feita com a câmera. Obtivemos resultados para a calibração WYSIWYG entre monitores e monitor e impressora com uma média de Eab menor que 6. Os resultados são mostrados e discutidos ao longo da dissertação, bem como um modelo de erros. _________________________________________________________________________________ ABSTRACTIn environments with a multitude of monitors and printers, and where coherence of color representation is required, device cal ibration is vital. Calibration is in general performed using colorimetric tools, usually requiring sophisticated devices such as colorimeters or spectrophotometers. We propose a cheaper method to perform non-colorimetric calibration using regular digital cameras as surrogates of colorimeters. For that, we use the camera as a simple mapping device and calibration is done by reference, i.e. a device is calibrated to have the response of another “reference” device. We devise methods to avoid or minimize camera adaptation and to deal with Metamerism. Both can impair the measurements made by the camera. We obtained results for WYSIWYG calibration between disparate monitors yielding an average Eab lower than 6. Results are shown and discussed along with an error model
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Calibração de dispositivos a cores utilizando uma camera digital
2006Co-Authors: Leite, Frederico NogueiraAbstract:Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2006.Em ambientes que possuem uma grande quantidade de monitores e impressoras, onde a coerência de representação de cor é requerida, a calibração de dispositivo é fundamental. Calibração é em geral executada utilizando ferramentas colorimétricas, usualmente requerendo dispositivos sofisticados como colorímetros ou espectrofotômetros. Nesta tese propomos um método mais barato de executar a calibração de maneira não colorimétrica utilizando uma câmera digital como substituta do colorímetro. Para isto, utilizamos a câmera como um simples dispositivo de mapeamento. A calibração é feita a partir de referencias, isto é, um dispositivo é calibrado tendo como referência outro dispositivo. Desenvolvemos um método de evitar ou minimizar a adaptação da câmera e a lidar com Metamerismo. Ambos podem prejudicar a medição feita com a câmera. Obtivemos resultados para a calibração WYSIWYG entre monitores e monitor e impressora com uma média de Eab menor que 6. Os resultados são mostrados e discutidos ao longo da dissertação, bem como um modelo de erros. _________________________________________________________________________________ ABSTRACTIn environments with a multitude of monitors and printers, and where coherence of color representation is required, device cal ibration is vital. Calibration is in general performed using colorimetric tools, usually requiring sophisticated devices such as colorimeters or spectrophotometers. We propose a cheaper method to perform non-colorimetric calibration using regular digital cameras as surrogates of colorimeters. For that, we use the camera as a simple mapping device and calibration is done by reference, i.e. a device is calibrated to have the response of another “reference” device. We devise methods to avoid or minimize camera adaptation and to deal with Metamerism. Both can impair the measurements made by the camera. We obtained results for WYSIWYG calibration between disparate monitors yielding an average Eab lower than 6. Results are shown and discussed along with an error model
Shanduan Zhang - One of the best experts on this subject based on the ideXlab platform.
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led light with enhanced color saturation and improved white light perception
Optics Express, 2016Co-Authors: Xiangfen Feng, Qiuyi Han, Shanduan ZhangAbstract:The light emitting diodes (LEDs) with high light quality were investigated to enhance the color appearance of the illuminated objects and increase the white light perception of the ambience. The spectral power distributions of the LED lights were optimized by addition of the RGB components and by shifting the color coordinate below the blackbody line to get desired color rendering index (CRI) and high gamut area index (GAI). The results of the human factor study reveal that the “perfect” white light can be achieved to both enhance color saturation and improve light visual impression. The effects of observer Metamerism were studied to clarify the observed phenomenon that the white lights with the same color coordinates were perceived differently by real observers.
