The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Manuel Melgosa - One of the best experts on this subject based on the ideXlab platform.
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revisiting the weighting function for lightness in the ciede2000 colour Difference Formula
Coloration Technology, 2017Co-Authors: Manuel Melgosa, Claudio Oleari, Pedro J Pardo, Min Huang, Changjun LiAbstract:We have used 13 experimental datasets (7420 colour pairs) to study the performance of the weighting function for lightness proposed by the CIEDE2000 colour-Difference Formula, because it has been suggested that this function can be improved by using the weighting function for lightness SL = 1 adopted by the CIE94 colour-Difference Formula. Using the standardised residual sum of squares (STRESS) index, it was found that: (i) replacing the SL in CIEDE2000 with SL = 1 improved the results for 7/13 datasets considered, but the improvement was statistically significant only for 1/13 datasets; (ii) a Whittle-type lightness-Difference Formula can be used to replace the term ∆L*/SL in CIEDE2000, which led to a new colour-Difference Formula with no statistically significant Difference with respect to CIEDE2000 for any of the 13 experimental datasets. A modification of the CIEDE2000 Formula using a Whittle-type lightness Formula is proposed.
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Power functions improving the performance of color-Difference Formulas.
Optics Express, 2015Co-Authors: Min Huang, Manuel Melgosa, M. Sánchez-marañón, Changjun LiAbstract:Color-Difference Formulas modified by power functions provide results in better agreement with visually perceived color Differences. Each of the modified color-Difference Formulas proposed here adds only one relevant parameter to the corresponding original color-Difference Formula. Results from 16 visual data sets and 11 color-Difference Formulas indicate that the modified Formulas achieve an average decrease of 5.7 STRESS (Standardized Residual Sum of Squares) units with respect to the original Formulas, signifying an improvement of 17.3%. In particular, for these 16 visual data sets, the average decrease for the current CIE/ISO recommended color-Difference Formula CIEDE2000 modified by an exponent 0.70 was 5.4 STRESS units (17.5%). The improvements of all modified color-Difference Formulas with respect to the original ones held for each of the 16 visual data sets and were statistically significant in most cases, particularly for all data sets with color Differences close to the threshold. Results for 2 additional data sets with color pairs in the blue and black regions of the color space confirmed the usefulness of the proposed power functions. The main reason of the improvements found for the modified color-Difference Formulas with respect to the original color-Difference Formulas seems to be the compression provided by power functions.
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Measuring color Differences in automotive samples with lightness flop: A test of the AUDI2000 color-Difference Formula
Optics Express, 2014Co-Authors: Manuel Melgosa, Juan Martinez-garcia, Luis Gomez-robledo, Esther Perales, Francisco Martinez-verdu, Thomas DauserAbstract:From a set of gonioapparent automotive samples from different manufacturers we selected 28 low-chroma color pairs with relatively small color Differences predominantly in lightness. These color pairs were visually assessed with a gray scale at six different viewing angles by a panel of 10 observers. Using the Standardized Residual Sum of Squares (STRESS) index, the results of our visual experiment were tested against predictions made by 12 modern color-Difference Formulas. From a weighted STRESS index accounting for the uncertainty in visual assessments, the best prediction of our whole experiment was achieved using AUDI2000, CAM02-SCD, CAM02-UCS and OSA-GP-Euclidean color-Difference Formulas, which were no statistically significant different among them. A two-step optimization of the original AUDI2000 color-Difference Formula resulted in a modified AUDI2000 Formula which performed both, significantly better than the original Formula and below the experimental inter-observer variability. Nevertheless the proposal of a new revised AUDI2000 color-Difference Formula requires additional experimental data.
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Testing the AUDI2000 colour-Difference Formula for solid colours using some visual datasets with usefulness to automotive industry
8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics Lasers and Applications, 2013Co-Authors: Juan Martinez-garcia, Manuel Melgosa, Min Huang, Hao-xue Liu, Luis Gomez-robledo, Guihua Cui, M. Ronnier Luo, Thomas DauserAbstract:Colour-Difference Formulas are tools employed in colour industries for objective pass/fail decisions of manufactured products. These objective decisions are based on instrumental colour measurements which must reliably predict the subjective colour-Difference evaluations performed by observers’ panels. In a previous paper we have tested the performance of different colour-Difference Formulas using the datasets employed at the development of the last CIErecommended colour-Difference Formula CIEDE2000, and we found that the AUDI2000 colour-Difference Formula for solid (homogeneous) colours performed reasonably well, despite the colour pairs in these datasets were not similar to those typically employed in the automotive industry (CIE Publication x038:2013, 465-469). Here we have tested again AUDI2000 together with 11 advanced colour-Difference Formulas (CIELUV, CIELAB, CMC, BFD, CIE94, CIEDE2000, CAM02-UCS, CAM02-SCD, DIN99d, DIN99b, OSA-GP-Euclidean) for three visual datasets we may consider particularly useful to the automotive industry because of different reasons: 1) 828 metallic colour pairs used to develop the highly reliable RIT-DuPont dataset (Color Res. Appl. 35, 274-283, 2010); 2) printed samples conforming 893 colour pairs with threshold colour Differences (J. Opt. Soc. Am. A 29, 883-891, 2012); 3) 150 colour pairs in a tolerance dataset proposed by AUDI. To measure the relative merits of the different tested colour-Difference Formulas, we employed the STRESS index (J. Opt. Soc. Am. A 24, 1823-1829, 2007), assuming a 95% confidence level. For datasets 1) and 2), AUDI2000 was in the group of the best colour-Difference Formulas with no significant Differences with respect to CIE94, CIEDE2000, CAM02-UCS, DIN99b and DIN99d Formulas. For dataset 3) AUDI2000 provided the best results, being statistically significantly better than all other tested colour-Difference Formulas.
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fuzzy analysis for detection of inconsistent data in experimental datasets employed at the development of the ciede2000 colour Difference Formula
Journal of Modern Optics, 2009Co-Authors: Samuel Morillas, Rafael Huertas, Luis Gomezrobledo, Manuel MelgosaAbstract:Relating instrumental measurements to visually perceived colour-Differences, under specific illuminating and viewing conditions, is one of the challenges of advanced colorimetry. Experimental data are used to devise new colour-Difference Formulas as well as to assess the performance of other colour-Difference Formulas. In this paper, we analyse the consistency of experimental data employed at the development of the last CIE recommended colour-Difference Formula, CIEDE2000. Because of the subjective and imprecise nature of these data, we adopt a fuzzy approach, so that finally, for each experimental datum, we establish the fuzzy degree to which it can be considered consistent with the remaining data. The results of our analyses show that only a few data are associated with a rather low degree of consistency. These data in many cases correspond to colour pairs with a very small colour-Difference for which visual assessments seem to be overestimated.
Min Huang - One of the best experts on this subject based on the ideXlab platform.
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revisiting the weighting function for lightness in the ciede2000 colour Difference Formula
Coloration Technology, 2017Co-Authors: Manuel Melgosa, Claudio Oleari, Pedro J Pardo, Min Huang, Changjun LiAbstract:We have used 13 experimental datasets (7420 colour pairs) to study the performance of the weighting function for lightness proposed by the CIEDE2000 colour-Difference Formula, because it has been suggested that this function can be improved by using the weighting function for lightness SL = 1 adopted by the CIE94 colour-Difference Formula. Using the standardised residual sum of squares (STRESS) index, it was found that: (i) replacing the SL in CIEDE2000 with SL = 1 improved the results for 7/13 datasets considered, but the improvement was statistically significant only for 1/13 datasets; (ii) a Whittle-type lightness-Difference Formula can be used to replace the term ∆L*/SL in CIEDE2000, which led to a new colour-Difference Formula with no statistically significant Difference with respect to CIEDE2000 for any of the 13 experimental datasets. A modification of the CIEDE2000 Formula using a Whittle-type lightness Formula is proposed.
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Power functions improving the performance of color-Difference Formulas.
Optics Express, 2015Co-Authors: Min Huang, Manuel Melgosa, M. Sánchez-marañón, Changjun LiAbstract:Color-Difference Formulas modified by power functions provide results in better agreement with visually perceived color Differences. Each of the modified color-Difference Formulas proposed here adds only one relevant parameter to the corresponding original color-Difference Formula. Results from 16 visual data sets and 11 color-Difference Formulas indicate that the modified Formulas achieve an average decrease of 5.7 STRESS (Standardized Residual Sum of Squares) units with respect to the original Formulas, signifying an improvement of 17.3%. In particular, for these 16 visual data sets, the average decrease for the current CIE/ISO recommended color-Difference Formula CIEDE2000 modified by an exponent 0.70 was 5.4 STRESS units (17.5%). The improvements of all modified color-Difference Formulas with respect to the original ones held for each of the 16 visual data sets and were statistically significant in most cases, particularly for all data sets with color Differences close to the threshold. Results for 2 additional data sets with color pairs in the blue and black regions of the color space confirmed the usefulness of the proposed power functions. The main reason of the improvements found for the modified color-Difference Formulas with respect to the original color-Difference Formulas seems to be the compression provided by power functions.
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Testing the AUDI2000 colour-Difference Formula for solid colours using some visual datasets with usefulness to automotive industry
8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics Lasers and Applications, 2013Co-Authors: Juan Martinez-garcia, Manuel Melgosa, Min Huang, Hao-xue Liu, Luis Gomez-robledo, Guihua Cui, M. Ronnier Luo, Thomas DauserAbstract:Colour-Difference Formulas are tools employed in colour industries for objective pass/fail decisions of manufactured products. These objective decisions are based on instrumental colour measurements which must reliably predict the subjective colour-Difference evaluations performed by observers’ panels. In a previous paper we have tested the performance of different colour-Difference Formulas using the datasets employed at the development of the last CIErecommended colour-Difference Formula CIEDE2000, and we found that the AUDI2000 colour-Difference Formula for solid (homogeneous) colours performed reasonably well, despite the colour pairs in these datasets were not similar to those typically employed in the automotive industry (CIE Publication x038:2013, 465-469). Here we have tested again AUDI2000 together with 11 advanced colour-Difference Formulas (CIELUV, CIELAB, CMC, BFD, CIE94, CIEDE2000, CAM02-UCS, CAM02-SCD, DIN99d, DIN99b, OSA-GP-Euclidean) for three visual datasets we may consider particularly useful to the automotive industry because of different reasons: 1) 828 metallic colour pairs used to develop the highly reliable RIT-DuPont dataset (Color Res. Appl. 35, 274-283, 2010); 2) printed samples conforming 893 colour pairs with threshold colour Differences (J. Opt. Soc. Am. A 29, 883-891, 2012); 3) 150 colour pairs in a tolerance dataset proposed by AUDI. To measure the relative merits of the different tested colour-Difference Formulas, we employed the STRESS index (J. Opt. Soc. Am. A 24, 1823-1829, 2007), assuming a 95% confidence level. For datasets 1) and 2), AUDI2000 was in the group of the best colour-Difference Formulas with no significant Differences with respect to CIE94, CIEDE2000, CAM02-UCS, DIN99b and DIN99d Formulas. For dataset 3) AUDI2000 provided the best results, being statistically significantly better than all other tested colour-Difference Formulas.
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a discussion on printing color Difference tolerance by ciede2000 color Difference Formula
Applied Mechanics and Materials, 2012Co-Authors: Hao-xue Liu, Yu Liu, Min HuangAbstract:In ISO printing standards, a color Difference tolerance of ΔE*ab=5 is used as a threshold. But CIELAB color space is not uniform enough so that the same color Difference value represents different color Difference sensation in different color area. It is proved that the color Difference calculated by CIEDE2000 is closer to the human sensation, so ISO TC130 is discussing the possibility of replacing CIELAB color Difference by CIEDE2000. An experiment was conducted, in which the color Difference of typical printing colors, CMYKRGB, was calculated and test. The experimental results showed that the color Difference tolerance of ΔE*ab=5 is corresponding to 0.95~6.42 by CIEDE2000, with the average of 3.30 ΔE*00. So a color Difference tolerance of ΔE*00=3.3 or a somewhat looser value of ΔE*00=3.5 can be adopted as a new tolerance for printing industry.
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Image color-Difference evaluation based on color-Difference Formula
2011 4th International Congress on Image and Signal Processing, 2011Co-Authors: Hao-xue Liu, Meng Xie, Min HuangAbstract:To study the relationship between calculated mean color-Difference and visual perception of color digital images, a visual assessment experiment was designed and carried out. Based on the experimental results and color-Difference Formula, the performance of CIELAB, CIEDE2000 and CMC color-Difference Formula on evaluating image color-Difference were tested and evaluated in their original form and amendment form, and the coefficient of color-Difference was optimized.
Hisamatsu Nakano - One of the best experts on this subject based on the ideXlab platform.
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Modified Finite-Difference Formula for the Analysis of a Step-Index Waveguide with a Tilted Interface
Advances in Optical Sciences Congress, 2009Co-Authors: Junji Yamauchi, Seiji Harada, Shingo Kobori, Hisamatsu NakanoAbstract:A 3-point finite-Difference Formula is derived for the analysis of a step-index waveguide with a tilted interface. The Formula is suitable for the use of the alternating-direction implicit method.
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Semivector Finite-Difference Formula for the Analysis of a Step-Index Waveguide With a Tilted Interface
IEEE Photonics Technology Letters, 2009Co-Authors: Junji Yamauchi, Seiji Harada, Shingo Kobori, Hisamatsu NakanoAbstract:A three-point finite-Difference Formula is derived for the analysis of a step-index waveguide with a tilted interface. The Formula is suitable for the use of the alternating-direction implicit method. Through the analysis of a rib waveguide with a sloped side wall and a hollow triangular waveguide, improvement in accuracy and stability is demonstrated.
Osamu Yokosuka - One of the best experts on this subject based on the ideXlab platform.
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objective evaluation of visibility in virtual chromoendoscopy for esophageal squamous carcinoma using a color Difference Formula
Journal of Biomedical Optics, 2010Co-Authors: Masahito Inoue, Yoichi Miyake, Takeo Odaka, Toru Sato, Yoshiyuki Watanabe, Atsunori Sakama, Satoki Zenbutsu, Osamu YokosukaAbstract:Computed virtual chromoendoscopy with flexible spectral imaging color enhancement (FICE) is a new dyeless imaging technique that enhances mucosal and vascular patterns. However, a method for selecting a suitable wavelength for a particular condition has not been established. The aim of this study is to evaluate the color Difference method for quality assessment of FICE images of the intrapapillary capillary loop in magnifying endoscopy for esophageal squamous cell carcinoma. The color Difference between 60 microvessels and background mucosa observed using the magnifying endoscope was 8.31±2.84 SD under white light and 12.26±3.14 (p=0.0031), 11.70±4.49 (p=0.0106), and 17.49±5.40 (p<0.0001) in FICE modes A, B, and C, respectively. The visibility scores for microvessels observed by medical students were 6.00±1.12 points under white light and 11.1±2.25 (p<0.0001), 8.65±2.06 (p=0.0001), and 12.55±2.56 (p<0.0001) in FICE modes A, B, and C, respectively. Furthermore, the measurement of color Difference was correlated with the visibility score assigned by medical students (Pearson's correlation coefficient=0.583, p<0.0001) In conclusion, the color Difference method corresponds to human vision and is an appropriate method for evaluation of endoscopic images.
H Nakano - One of the best experts on this subject based on the ideXlab platform.
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modified finite Difference Formula for semivectorial h field solutions of optical waveguides
IEEE Photonics Technology Letters, 1998Co-Authors: J Yamauchi, G Takahashi, H NakanoAbstract:The propagation constants of rib waveguides are analyzed by the imaginary distance beam-propagation method based on a newly derived finite-Difference Formula for semivectorial H-fields. The Formula ensures a truncation error of O(/spl Delta/x)/sup 2/, provided that the discontinuity lies midway between two mesh points. Comparison with previously published results for a rib waveguide as a classical benchmark shows the effectiveness of the present method.
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modified finite Difference Formula for the analysis of semivectorial modes in step index optical waveguides
IEEE Photonics Technology Letters, 1997Co-Authors: J Yamauchi, M Sekiguchi, O Uchiyama, Jun Shibayama, H NakanoAbstract:The modified finite-Difference Formula is presented for the second derivative of a semivectorial field in a step-index optical waveguide. The present Formula achieves a truncation error of O(/spl Delta/x/sup 2/) provided the discontinuity coincides with a mesh point or lies midway between two mesh points. Furthermore, the Formula allows a general position of the interface, when used with the beam-propagation method (BPM). To demonstrate the effectiveness of the Formula, asymmetric step-index waveguides are analyzed using the imaginary-distance BPM.
