Assessing the variability of colour-rendering indices using a random test-colour method / Pedro J. Pardo in COLORATION TECHNOLOGY, Vol. 133, N° 5 (10/2017)  

[article]  inCOLORATION TECHNOLOGY > Vol. 133, N° 5 (10/2017) . - p. 403-414 Titre : Assessing the variability of colour-rendering indices using a random test-colour method Type de document : texte imprimé Auteurs : Pedro J. Pardo, Auteur ; Maria Suero, Auteur ; Angel L. Pérez, Auteur ; Jairo Mena, Auteur ; Manuel Melgosa, Auteur Année de publication : 2017 Article en page(s) : p. 403-414 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Eclairage Evaluation Lumière artificielle Réflectance vision des couleurs Index. décimale : 535.6 Couleur Résumé : This paper addresses the way in which the random selection of different sets of samples influences the values of two colour-rendering indices analogous to the ones proposed by the International Commission on Illumination (CIE Publ. 13.3, 1995), Ra, and the Illuminating Engineering Society (IES Technical Memorandum TM-30-15, 2015), Rf. We report results found for 11 light sources, representative of current indoor and outdoor lighting, using a database with 12 123 spectral reflectance factors from real objects. For these 11 light sources, the differences between official Ra and Rf values and those computed using 100 iterations with 6000 random samples from our database proved to be in the range [?13, 2] and [?15, ?1], respectively, the highest differences corresponding to sources with narrow peaks in their spectral power distributions. For 100 random subsets of 10 samples from our database, the average standard deviations of the 11 light sources for indices analogous to Ra and Rf were 8 and 5 (or 2 and 1 using 110 samples) respectively. The standard deviations in computed Ra and Rf values, using subsets with different numbers of samples n, can be modelled as inversely proportional to the square root of n. We propose a method to estimate these standard deviations for n = 6000 using reduced sets of 10 spectral reflectance factors. Note de contenu : - EXPERIMENTAL METHODS : Samples - Light sources - Procedures - RESULTS AND DISCUSSION : CRI declared values vs values found with random sets of samples - Analysis of the internal standard deviations - Analysis of the external standard deviations - Relationship between internal and external standard deviations - Worked examples DOI : 10.1111/cote.12293 En ligne : https://drive.google.com/file/d/1qEqYpRA0wIvAxE0tK5GzX05o54QSak7_/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29199 [article]

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Revisiting the Optical Society of America Uniform Color Scales system : past, present and future challenges / Manuel Melgosa in COLORATION TECHNOLOGY, Vol. 137, N° 1 (02/2021)  

[article]  inCOLORATION TECHNOLOGY > Vol. 137, N° 1 (02/2021) . - p. 33-37 Titre : Revisiting the Optical Society of America Uniform Color Scales system : past, present and future challenges Type de document : texte imprimé Auteurs : Manuel Melgosa, Auteur ; Dibakar Pant, Auteur ; Gabriele Simone, Auteur Année de publication : 2021 Article en page(s) : p. 33-37 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 535.6 Couleur Résumé : As a tribute to Claudio Oleari (1944-2018), in this article we remember some of his ideas about the role of physics and engineering in modern colour science. In particular, we consider his emphasis on the strong content of the work carried out during 1947-1974 by the Committee on Uniform Scales of the Optical Society of America. Oleari considered the Optical Society of America Uniform Color scales system a very useful basis for new developments in colour science, including approximately uniform colour spaces, colour difference formulae and chromatic adaptation transforms. Papers published by Oleari and colleagues constitute an original alternative approach to the current generalised assumption of CIELAB made by most researchers and practitioners of colour science. We should seek a deeper understanding of colour vision to allow the development of new colour spaces, in which colour appearance could be more neatly expressed. Note de contenu : - OSA-UCS system colour atlas and colour spaces - Colour differences and chromatic adaptation DOI : 10.1111/cote.12509 En ligne : https://onlinelibrary.wiley.com/doi/epdf/10.1111/cote.12509 Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35586 [article]

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Revisiting the weighting function for lightness in the CIEDE2000 colour-difference formula / Manuel Melgosa in COLORATION TECHNOLOGY, Vol. 133, N° 4 (08/2017)  

[article]  inCOLORATION TECHNOLOGY > Vol. 133, N° 4 (08/2017) . - p. 274-282 Titre : Revisiting the weighting function for lightness in the CIEDE2000 colour-difference formula Type de document : texte imprimé Auteurs : Manuel Melgosa, Auteur ; Guihua Cui, Auteur ; Claudio Oleari, Auteur ; Pedro J. Pardo, Auteur ; Min Huang, Auteur ; Changjun Li, Auteur ; Ming Ronnier Luo, Auteur Année de publication : 2017 Article en page(s) : p. 274-282 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Colorimétrie Fonction de pondération Index. décimale : 535.6 Couleur Résumé : 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. Note de contenu : - Influence of the four constants in the Sl function of CIEDE2000 - Replacement of ?L*/SL by a new lightness function based on the whittle formula - STRESS results using CIEDE2000 and two CIEDE2000-modified formulas DOI : 10.1111/cote.12294 En ligne : https://drive.google.com/file/d/1mNNKRQVoKWPADqH4d1JgEsji7TJE6dy2/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28879 [article]

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