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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Colour appearance in immersive three-dimensional virtual environments / Francisco Diaz-Barrancas in COLORATION TECHNOLOGY, Vol. 137, N° 1 (02/2021)  

[article]  inCOLORATION TECHNOLOGY > Vol. 137, N° 1 (02/2021) . - p. 38-43 Titre : Colour appearance in immersive three-dimensional virtual environments Type de document : texte imprimé Auteurs : Francisco Diaz-Barrancas, Auteur ; Halina Carmen Cwierz, Auteur ; Pedro J. Pardo, Auteur ; Angel L. Pérez, Auteur ; Maria Isabel Suero, Auteur Année de publication : 2021 Article en page(s) : p. 38-43 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 535.6 Couleur Résumé : Technology is constantly evolving and, consequently, all the technological advances taking place are regularly integrated into the daily life of society. During recent years, there has been a trend towards virtual resources such as teleworking, telemedicine and e-commerce. In many countries, this virtualisation process has been accelerated by the changing circumstances caused by the COVID-19 pandemic. In any case, there is a growing demand for virtual systems, and virtual reality is a suitable field for the application of a multitude of solutions. However, advances in virtual reality occur without any regard to colour science, and there are several challenges to be overcome to improve the visual appearance and fidelity of colour reproduction in all types of related devices. This paper discusses three open issues related to the visual appearance and visual fidelity of virtual reality systems. We believe it is necessary to direct future research efforts in each of these directions to secure improvements in the visual fidelity of virtual reality systems. Note de contenu : - Measurement of optical properties related to colour appearance - Real-time 3D rendering images for VR - Colour appearance models applied to rendered scenes - Fig. 1 : Graphical representation of BSDF = BRDF + BTDF, where BSDF is the bidirectional scattering distribution function, BRDF is the bidirectional reflectance distribution function, and BTDF is the bidirectional transmittance distribution function - Fig. 2 : Example of a photorealistic reproduction of a real scene produced with POV-Ray 3.6 - Fig. 3 : ColorChecker simulation using a two spectral peaks light source in a virtual reality system and a real picture of the ColorChecker using a two spectral peaks light source - Fig. 4 : Real picture of a real scene inside a light booth, (centre) screen capture of the simulation of a real scene in a virtual reality system (VRS) without any post-processing, and screen capture of the simulation of a real scene in a VRS processed with an iCAM06 appearance model DOI : 10.1111/cote.12513 En ligne : https://onlinelibrary.wiley.com/doi/epdf/10.1111/cote.12513 Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35587 [article]

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Correlation of various light source quality indices with the colour discrimination capacity / Eduardo M. Cordero in COLORATION TECHNOLOGY, Vol. 127, N° 2 (2011)  

[article]  inCOLORATION TECHNOLOGY > Vol. 127, N° 2 (2011) . - p. 136-144 Titre : Correlation of various light source quality indices with the colour discrimination capacity Type de document : texte imprimé Auteurs : Eduardo M. Cordero, Auteur ; Pedro J. Pardo, Auteur ; Angel L. Pérez, Auteur ; Maria Suero, Auteur Année de publication : 2011 Article en page(s) : p. 136-144 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Sources de lumière vision des couleurs Index. décimale : 535.6 Couleur Résumé : The quality of a light source can be measured against various criteria – colour rendering, durability, etc. Another criterion is the quality of the colour of the objects it illuminates. Traditionally, this aspect has been associated almost exclusively with that of colour rendering, but the emergence of new light-emitting diode technology light sources has led to its being re-examined. In particular, questions have been raised as to whether colour quality can be calculated by a single measure. Instead, it seems a multidimensional index might better cover such concepts as colour rendering, colour discrimination, harmony, etc. The present work describes a visual colour discrimination experiment whose results corroborate the existence of a multidimensional index, even although some of the parameters commonly used to describe the quality of a light source might be correlated with each other. Note de contenu : - Test design - Apparatus - Sample - Colour discrimination tests DOI : 10.1111/j.1478-4408.2011.00288.x En ligne : http://onlinelibrary.wiley.com/doi/10.1111/j.1478-4408.2011.00288.x/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12228 [article]

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