Assessment of sparkle and graininess in effect coatings using a high-resolution gonioreflectometer and psychophysical studies / Jiri Filip in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 18, N° 6 (11/2021)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 18, N° 6 (11/2021) . - p. 1511-1530 Titre : Assessment of sparkle and graininess in effect coatings using a high-resolution gonioreflectometer and psychophysical studies Type de document : texte imprimé Auteurs : Jiri Filip, Auteur ; Radomir Vavra, Auteur ; Martina Kolafova, Auteur ; Frank J. Maile, Auteur Année de publication : 2021 Article en page(s) : p. 1511-1530 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Evaluation visuelle Goniométrie Granulation Pigments à effets spéciaux Psychophysique La psychophysique est une branche de la psychologie expérimentale qui cherche à déterminer les relations quantitatives qui existent entre un stimulus physique et la perception qu'on en a. La psychophysique s'intéresse aux sens physiologiques tels que la vue, l'ouïe, le toucher (plus rarement l'odorat ou le goût) mais aussi à des sensations comme la perception du temps ou du mouvement. Revêtements -- Texture Surfaces -- Perception visuelle Index. décimale : 667.9 Revêtements et enduits Résumé : The aim of this article is to propose a model to automatically predict visual judgement of sparkle and graininess of special effect pigments used in industrial coatings. Many applications in the paint and coatings, printing and plastics industry rely on multi-angle color measurements with the aim of properly characterizing the appearance, i.e., the color and texture of the manufactured surfaces. However, when it comes to surfaces containing effect pigments, these methods are in many cases insufficient and it is particularly texture characterization methods that are needed. There are two attributes related to texture that are commonly used: (1) diffuse coarseness or graininess and (2) sparkle or glint impression. In this paper, we analyzed visual perception of both texture attributes using two different psychophysical studies of 38 samples painted with effect coatings including different effect pigments and 31 test persons. Our previous work has shown a good agreement between a study using physical samples with one that uses high-resolution photographs of these sample surfaces. We have also compared the perceived (1) graininess and (2) sparkle with the performance of two commercial instruments that are capable of capturing both attributes. Results have shown a good correlation between the instruments’ readings and the psychophysical studies. Finally, we implemented computational models predicting these texture attributes that have a high correlation with the instrument readings as well as the psychophysical data. By linear scaling of the predicted data using instruments readings, one can use the proposed model for the prediction of graininess and both static and dynamic sparkle values. Note de contenu : - RELATED WORK : Visual assessment of effect coatings textures - Modeling and visualization of texture effects of effect coatings - Industrial characterization of texture - TESTED COATINGS - METHODOLOGY : experiment 1 - Real samples - Experiment 2 - Photographs of samples - EXPERIMENTS : Psychophysical evaluation of real samples - Psychophysical evaluation of photographs - Discussion of limitations - COMPARISON TO INDUSTRIAL DEVICES - PREDICTION OF SPARKLE AND GRAININESS : Sparkle model - Graininess model - IMPLICATION TO DYNAMIC SPARKLE MODEL - Table 1 : Correlations of graininess and sparkle values between experiments using real samples and their photographs for viewing polar angle θv=45∘ - Table 2 : A list of the tested effect coating samples and their composition - Table 3 : CIE Lab values of the tested coatings and results of their sparkle (S) and graininess (G) psychophysical assessment using real samples and their photographs/video DOI : https://doi.org/10.1007/s11998-021-00518-5 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00518-5.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36805 [article]

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Optical analysis of coatings including diffractive pigments using a high-resolution gonioreflectometer / Jiri Filip in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 16, N° 2 (03/2019)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 16, N° 2 (03/2019) . - p. 555-572 Titre : Optical analysis of coatings including diffractive pigments using a high-resolution gonioreflectometer Type de document : texte imprimé Auteurs : Jiri Filip, Auteur ; Radomir Vavra, Auteur ; Frank J. Maile, Auteur Année de publication : 2019 Article en page(s) : p. 555-572 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Diffraction Goniométrie Pigments à effets spéciaux Revêtements -- Propriétés optiques Spectroscopie de réflectance Index. décimale : 667.9 Revêtements et enduits Résumé : The aim of this article is to demonstrate a new way of measuring and understanding the appearance of pigment flake orientation and texture in special effect pigments for use in industrial coatings. We have used diffractive pigments and analyzed the relative orientation of the particles in the coating layers by evaluating their behavior in two common industry applications: solventborne and powder coatings. We have measured the interference color by taking readings with a high-resolution gonioreflectometer, in order to test the viability of automatic diffractive pigment evaluation. The results were analyzed using both psychophysical (i.e., human) and computational (i.e., mechanical) methods. Our later psychophysical and computational analysis of the visual differences that diffractive pigments present in both solventborne (1) and powder coating (2) systems for in-plane and out-of-plane geometries revealed that solventborne liquid paint systems better preserve the appearance of original diffraction gratings. This is due to enhanced orientation of the anisotropic pigment particles. The powder coating surfaces investigated, on the other hand, preserved higher intensity and thus visibility in randomly oriented solitary flakes, creating a greater sparkle contrast. We confirmed our findings by capturing and visualizing coating appearance by means of a bidirectional texture function. We then compared the diffractive pigment evaluation results with other state-of-the-art measuring device readings. We believe that our work provides valuable information on flake orientation and also compares pigment performance in a range of industrial coating systems, which may enable industrial companies to improve paint spraying processes. Note de contenu : - INTRODUCTION : The use of diffractive pigments in industry - The optical appearance of surfaces including diffractive pigments - Manufacture of diffractive pigments - Coatings systems analyzed for this study and panel preparation - EXISTING ANALYSIS METHODS FOR EFFECT COATINGS TO DATE : Angular analysis of effect pigments in general - Analysis of coatings containing diffractive pigments - Texture analysis of effect coatings - MOTIVATION EXPERIMENT ON THE VISUAL APPEARANCE OF DIFFRACTIVE PIGMENTS - DEVELOOPMENT OF AN AUTOMATIC METHOD OF DIFFRACTIVE PIGMENT : Apearance acquisition system - Geometry decription - ANALYSIS : Psychophysical analysis - Computational texture data analysis - EXPERIMENTS ON PIGMENTS OF VARYING CONCENTRATION : Higher pigmentation samples - Lower pigmentation samples - COMPARISON OF PROPOSED METHOD TO A STATE-OF-THE-ART TEXTURE MEASUREMENT DEVICE - CAPTURE APPEARANCE ON COATED OBJECTS DOI : 10.1007/s11998-018-0137-5 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-018-0137-5.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32425 [article]

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Waviness analysis of glossy surfaces based on deformation of a light source reflection / Jiri Filip in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 20, N° 5 (09/2023)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 20, N° 5 (09/2023) . - p. 1703-1712 Titre : Waviness analysis of glossy surfaces based on deformation of a light source reflection Type de document : texte imprimé Auteurs : Jiri Filip, Auteur ; Radomir Vavra, Auteur ; Frank J. Maile, Auteur Année de publication : 2023 Article en page(s) : p. 1703-1712 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Aspect peau d'orange (peinture) Brillance (optique) Mesure Ondulation Réflectance Revêtements Index. décimale : 667.9 Revêtements et enduits Résumé : The evaluation of waviness, also known as orange peel, is essential for the quality control of materials in industrial fields working with high gloss materials, e.g., coatings, automotive and metal fabrication. This paper presents an affordable noncontact method for waviness analysis based on a single image of the light source reflected from the surface under study. The spatial perturbations along the contour of the light source reflection are compared to the ideal contour and analyzed in the Fourier domain to obtain standard features that have been compared to commercial ripple characterization device. Additional three method-specific features are proposed and evaluated. Our method has been tested on a set of ten orange peel standards, ten effect, and three solid coating samples and shows promising performance in waviness characterization of glossy surfaces. Note de contenu : - RELATED WORK - PROPOSED METHOD OF WAVINESS ANALYSIS - EXPERIMENTS : Tested material samples - Measurement setup - Results for orange peel standards - Results for effect coatings - Results for challenging solid coatings - DISCUSSION AND LIMITATION - Table 1 : Relative values of standard deviations to mean values across the three readings of the same sample. Pearson’s correlations and Spearman’s rank correlations index between our features and ordering of a set of ten ACT panels - Table 2 : Pearson’s correlations between computed frequency and statistical features (rows) with the wave-scan readings (columns). A more significant correlation values with p values lower than 0.05 are in boldface - Table 3 : A list of the tested effect coating samples DOI : https://doi.org/10.1007/s11998-023-00775-6 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-023-00775-6.pdf?pdf=button% [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39982 [article]

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