Iridescence is the property that makes colors vary by angle of observation. Technology has made it possible to print with ink that has this anisotropic property. The ink that is used contains microparticles and therefore only specific printing methods can be used, for example screen printing. This comes with new demands on halftones, due to its procedure; dots cannot be too small, and keeping structures should be prioritized. To minimize costs and time, prints should be simulated before sending an order. In this thesis, different methods to halftone for screen printing with iridescent ink are developed. Three existing methods are compared to methods that are developed for this specific cause. The result is presented as a 2D-mask and as an interactive 3D-simulation, using data measured from real ink. Also, properties of iridescence are analyzed to separate it from diffuse colors. An OpenGL simulation tool was developed for simulating halftones on 3D-models. The ink reflectance spectra are represented by polynomials that take as input the wavelength and observation angle. Given an observation angle, a spectrum can be found, which can be converted to RGB and set as the output color in the fragment shader. The program uses an RGB-mask which is the combined masks of the halftone. This is loaded as a texture which indicates what polynomial to use. There is no perfect method that works for all types of images. Images that contain colors similar to the inks benefit from morphological halftoning (enhanced structures) for iridescent areas, or foreground, and hatching (an angle dependant grid pattern) for diffuse areas, or background. Other images, that contain mixed colors as cyan, yellow or magenta, benefit froma hue separation error diffusion, where masks are created by thresholding the hue where the mixed colors are error diffused.The actual prints confirmed the hypothesis that tone reproduction can be of lower priority while structure and depth preservance should be highly prioritized. Iridescent colors can be separated from diffuse colors by thresholding the saturation combined with value, or the lightness of the Lab-representation

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Titre de l'écran-titre (visionné le 25 septembre 2023) / La baie de Sept-Îles (BSI) abrite le port minéralier le plus important en Amérique du Nord, de même que quelques industries qui œuvrent dans l'extraction, la transformation et l'exportation de matière minérale. Afin de déterminer les impacts de ces activités portuaires d'importance sur les communautés de microorganismes, ainsi que des changements climatiques sur cet écosystème côtier, une combinaison du biosuivi environnemental et de l'approche paléoécologique a été utilisée dans ce projet. Grâce à la méthode de biosuivi environnemental, en analysant les échantillons d'eau de surface, les conditions de base actuelles de la BSI peuvent être déterminées, tandis qu'avec l'approche paléoécologique et l'analyse de sédiment, ce sont les variations temporelles du passé qui peuvent être déterminées. Les objectifs du projet sont d'évaluer la biomasse photosynthétique estivale dans les eaux de surface de la baie de Sept-Îles, d'explorer la diversité et la répartition des producteurs primaires dans ces eaux et d'explorer les assemblages de pigments présents dans une archive sédimentaire provenant de la BSI afin de quantifier les changements survenus depuis les 550 dernières années. Pour ce faire, les assemblages de pigments algaux et bactériens contenus dans les échantillons d'eau de surface et de sédiment ont été analysés avec la méthode de chromatographie liquide à haute performance (HPLC). Puisque chaque pigment est associé à un ou plusieurs taxons algaux ou bactériens, l'état de la communauté phytoplanctonique et benthique, ainsi que la biomasse algale de la BSI peuvent être estimés. Les résultats de ce projet de recherche nous permettent de conclure qu'il est difficile de déceler des effets des industries ou de l'achalandage maritime récent, bien qu'il semble que certains pigments soient moins abondants dans les sédiments récents que dans le passé, représentant l'ère préindustriel. Il est également difficile de distinguer les effets anthropiques directs des effets naturels liés aux changements climatiques. Pour cela, on devrait intégrer des marqueurs industriels spécifiques, tels certains métaux lourds ou particules relâchés par les industries. Ce travail contribue aux connaissances et à la compréhension de la dynamique à long-terme de l'environnement aquatique de la région de Sept-Îles. / The Bay of Sept-Iles (BSI) is home to the largest mineral port in North America, as well as a few industries involved in the extraction, processing, and export of mineral material. To determine the impacts of these important port activities and climate change on microbial communities, a combination of environmental biomonitoring and paleoecological approach was used in this project. Through the environmental biomonitoring method, by analyzing surface water samples, the current baseline conditions of the BSI can be determined, while with the paleoecological approach and sediment analysis, it is the temporal variations of the past that can be determined. The objectives of the project are to evaluate summer photosynthetic biomass in the surface waters of Sept-Iles Bay, to explore the diversity and distribution of primary producers in these waters, and to explore pigment assemblages present in a sedimentary archive from the BSI to quantify changes over the last 550 years. To do this, the assemblages of algal and bacterial pigments contained in the surface water and sediment samples were analyzed using the High-Performance Liquid Chromatography (HPLC) method. Since each pigment is associated with one or more algal or bacterial taxa, the state of the phytoplankton and benthic community, as well as the algal biomass of the BSI can be estimated. The results of this research project allow us to conclude that it is difficult to detect the effects of recent industries or maritime traffic, although it appears that some pigments are less abundant in recent sediments than in the past, representing the pre-industrial era. It is also difficult to distinguish direct anthropogenic effects from natural effects related to climate change. For this, we should integrate specific industrial markers, such as certain heavy metals or particles released by industries. This work contributes to the knowledge and understanding of the long-term dynamics of the aquatic environment of the Sept-Iles region.

Alfredo Volpi (1896 - 1988) é um dos mais importantes pintores brasileiros contemporâneos. Sua extensa obra foi marcada, principalmente, por composições cromáticas e abstrações geométricas. Foi um artista que dava importância muito grande à técnica e aos materiais, tendo desenvolvido uma maneira própria e sistemática de trabalhar: confeccionava suas próprias telas, tintas e até pigmentos, com terras naturais. Analisou-se ao todo 11 pinturas a têmpera em diversos suportes (tela, aglomerado de madeira e mural), 10 delas realizadas na década de 1950, período em que a obra do artista passou por uma grande transformação, do figurativismo ao abstracionismo e do uso de tintas industriais à base de óleo para a técnica medieval da têmpera. As características de opacidade, saturação cromática e presença material do pigmento sobre a superfície da tela, inerentes a esta técnica pictórica, tornam-se elementos tão importantes em sua obra, quanto o uso da cor na formação do espaço. Foram realizados estudos de cor e composição química dos materiais e levantamentos de informações sobre seus procedimentos técnico-artísticos a partir de métodos analíticos complementares não destrutivos e pesquisa em diversas fontes, pois entende-se que estes elementos são chaves importantes para o entendimento mais profundo de sua obra. O espectrofotômetro foi utilizado para medição da cor com base em curvas espectrais e coordenadas numéricas de referência dentro de um espaço de cor uniforme. Técnicas de imageamento por luz visível, fluorescência visível por radiação ultravioleta e reflectografia de infravermelho próximo foram utilizadas para levantar informações sobre o processo criativo do artista, detectar locais de intervenções de restauro e observar o grau de fluorescência de cada área cromática das pinturas como auxiliar na identificação de pigmentos. A técnica de EDXRF (Espectroscopia de Fluorescência de Raios X por Energia Dispersiva) foi importante para caracterização química dos materiais. O MEV-EDS (Microscópio Eletrônico de Varredura com Espectroscopia por Dispersão de Energia de Raios X) forneceu informações sobre composição química e imagens da superfície dos materiais presentes nas pinturas murais. A partir da integração destas informações pôde-se identificar uma parte da rica paleta deste pintor, documentar as cores das pinturas no presente, identificar ou dar indicações da composição dos pigmentos e da base de preparação das pinturas e iluminar partes da história de cada uma das obras, como presença de esboços feitos à grafite, pinturas anteriores encobertas, pinceladas e maneiras de misturar a tinta e documentar seu estado atual de conservação. As ferramentas utilizadas se mostraram úteis na caracterização das pinturas, revelaram informações inéditas sobre a obra deste artista e levantaram novas indagações. As informações obtidas podem ser o início de um banco de dados sobre sua obra. / Painter Alfredo Volpi (1896 - 1988) is one of the most important contemporary Brazilian artists. His extensive work, mostly characterised by chromatic compositions and geometric abstractions, is technically unique. The artist attributed great importance to craft and materials, developing his own systematic way of working. Among the paintings analysed were 11 temperasin various supports (canvas, hardboard panel and mortar). Of the selection, 10 paintings were made around 1950, when the artist\'s work underwent a major transformation, from figuration to abstraction, from the use of industrial oil-based paints to the medieval technique of tempera. This technique, known for its opacity, colour saturation and material presence of pigments on the canvas,became as important as the colour itself in the shaping of the artist\'s new spatial relation. It is understood that these elements are important keys to a deeper understanding of his work, both technically and artistically. The present investigation was carried out making use of non-destructive complementary analytical techniques. The aim was to study the chromatic and chemical composition characteristics of his paintings and gather information on the technical procedures the artist may have used. The spectrophotometer was used to measure the colour based on the spectral curves and numerical reference coordinates within a uniform colour space. Techniques of visual examination with visible light, visible fluorescence by ultraviolet radiation and near-infrared reflectography were used to gather information about the artist\'s creative process. These techniques also helped detect restoration patches and identify pigments. The EDXRF (Energy Dispersive X-Ray Fluorescence) technique was important for chemical characterization of materials, while the SEM-EDS (Scanning Electron Microscope with Energy Dispersive X-Ray Spectroscopy) provided surface images and information on the chemical composition of the material present in the murals. From the integration of these techniques it was possible to identify a part of the rich palette of Volpi´s paintings; to document the present aspects of the colours; to recognize or give indications of pigment and ground compositions and to shed light on parts of each of the works background, such as the presence of graphite sketches, covered earlier paintings and brushstrokes as well as to document the current condition of the works under study. The tools used have proven useful in characterizing the paintings, revealing new information about the work of the artist and raising new questions. The information obtained may be the beginning of a database on his oeuvre.

Anbaubegleitende spektral-optische Analysen direkt an der Pflanze haben zunehmend Bedeutung für die gartenbauliche Produktion. Veränderungen individueller Pflanzeninhaltsstoffe können mit Hilfe optischer Sensoren unmittelbar und beliebig oft erfasst werden, wodurch Pflanzenreaktionen auf veränderte Umgebungs- und Kulturbedingungen instrumentell messbar sind. Im Konzept eines Präzisionsgartenbau könnten diese zusätzlichen Informationen adaptiven Kulturmaßnahmen dienen und zur effizienten Nutzung von Ressourcen in der Produktion von Obst und Gemüse beitragen. Die wellenlängenspezifische Lichtabsorption pflanzlicher Gewebe ermöglicht zerstörungsfreie Reflexions- oder Transmissionsmessungen und die Adressierung von Pigmentgruppen im ultravioletten und sichtbaren Bereich des elektromagnetischen Spektrums. Auf Grund veränderlicher Gehalte während des Wachstum und der Entwicklung pflanzlicher Gewebe, sind Pigmente zudem wichtige Indikatoren für den physiologischen Zustand von Obst und Gemüse. Präzise zerstörungsfreie Spektralanalysen werden allerdings durch komplexe optische Eigenschaften biologischen Materials, besonders im Hinblick auf die Reifeentwicklung von Obst und Gemüse erschwert. Zur Lösung dieser Problematik wurde ein neuer iterativer Ansatz (iMLR) entwickelt, der überlagerte in-situ und in-vivo Spektren individueller Pigmente aus einem Summenmessspektrum separiert. Dieser Algorithmus wurde in eine eigenständige Applikation überführt. Eine Datenbank enthält spektrale Signaturen von Chlorophyll a und b, Lycopin, β-Carotin, α-Carotin, Lutein und Violaxanthin. Obwohl die spektrale Analyse einzelner Pigmente durch optische Störgrößen in komplex aufgebauten biologischen Geweben und Pigmentgemischen erschwert ist, konnte ein neuer Ansatz erarbeitet und validiert werden. Diese Methode minimiert spektrale Überlagerung von in-situ und in-vivo aufgezeichneten Messsummensignalen und analysiert Pigmentgehalte in Farbstoffgemische zuverlässig. / Spectral measurements on plants have already been introduced in practice through extensive research and through the recent increase in the availability of low-cost devices. It can be expected that optical sensor systems may contribute to an economic and sustainable use of natural resources as a part of the concept for precision horticulture. In terms of phytomonitoring approaches, such technologies which address variable amounts of individual chromophoric plant components become more important. Their wavelength-selective light absorption makes pigments specifically responsive to reflection or transmission recordings in the ultraviolet and visible range of the electromagnetic spectrum. Additionally, pigments serve as indicators for physiological stages of leaf and fruit. Consequently, the instrumental recording of variable pigment contents has high potential with regards to dynamic plant-adapted processes during the production of fruit and vegetables. Solving the known issues of non-destructive spectroscopy, a new approach was figured out in the present work to obtain a more precise analysis of individual pigment contents, which vary during the cultivation of horticultural crops. The tool is based on an iterative algorithm (iMLR), that separates coinciding in-situ and in-vitro spectra from sum signals of individual pigments. Finally, the algorithm was integrated into a stand-alone application containing a library of chlorophyll a and b, as well as signatures of lycopene, β-carotene, α-carotene, lutein and violaxanthin. It can be pointed out that individual pigment compositions are suitable indicators of the physiological stage of horticultural products. However, the spectral analysis of single pigment levels is challenging due to complex interactions of coinciding absorption and diffuse light scattering in natural pigment mixtures or in fruit extracts. From this, an improved method for the reliable decomposition of spectral signals was developed.

Alfredo Volpi (1896 - 1988) é um dos mais importantes pintores brasileiros contemporâneos. Sua extensa obra foi marcada, principalmente, por composições cromáticas e abstrações geométricas. Foi um artista que dava importância muito grande à técnica e aos materiais, tendo desenvolvido uma maneira própria e sistemática de trabalhar: confeccionava suas próprias telas, tintas e até pigmentos, com terras naturais. Analisou-se ao todo 11 pinturas a têmpera em diversos suportes (tela, aglomerado de madeira e mural), 10 delas realizadas na década de 1950, período em que a obra do artista passou por uma grande transformação, do figurativismo ao abstracionismo e do uso de tintas industriais à base de óleo para a técnica medieval da têmpera. As características de opacidade, saturação cromática e presença material do pigmento sobre a superfície da tela, inerentes a esta técnica pictórica, tornam-se elementos tão importantes em sua obra, quanto o uso da cor na formação do espaço. Foram realizados estudos de cor e composição química dos materiais e levantamentos de informações sobre seus procedimentos técnico-artísticos a partir de métodos analíticos complementares não destrutivos e pesquisa em diversas fontes, pois entende-se que estes elementos são chaves importantes para o entendimento mais profundo de sua obra. O espectrofotômetro foi utilizado para medição da cor com base em curvas espectrais e coordenadas numéricas de referência dentro de um espaço de cor uniforme. Técnicas de imageamento por luz visível, fluorescência visível por radiação ultravioleta e reflectografia de infravermelho próximo foram utilizadas para levantar informações sobre o processo criativo do artista, detectar locais de intervenções de restauro e observar o grau de fluorescência de cada área cromática das pinturas como auxiliar na identificação de pigmentos. A técnica de EDXRF (Espectroscopia de Fluorescência de Raios X por Energia Dispersiva) foi importante para caracterização química dos materiais. O MEV-EDS (Microscópio Eletrônico de Varredura com Espectroscopia por Dispersão de Energia de Raios X) forneceu informações sobre composição química e imagens da superfície dos materiais presentes nas pinturas murais. A partir da integração destas informações pôde-se identificar uma parte da rica paleta deste pintor, documentar as cores das pinturas no presente, identificar ou dar indicações da composição dos pigmentos e da base de preparação das pinturas e iluminar partes da história de cada uma das obras, como presença de esboços feitos à grafite, pinturas anteriores encobertas, pinceladas e maneiras de misturar a tinta e documentar seu estado atual de conservação. As ferramentas utilizadas se mostraram úteis na caracterização das pinturas, revelaram informações inéditas sobre a obra deste artista e levantaram novas indagações. As informações obtidas podem ser o início de um banco de dados sobre sua obra. / Painter Alfredo Volpi (1896 - 1988) is one of the most important contemporary Brazilian artists. His extensive work, mostly characterised by chromatic compositions and geometric abstractions, is technically unique. The artist attributed great importance to craft and materials, developing his own systematic way of working. Among the paintings analysed were 11 temperasin various supports (canvas, hardboard panel and mortar). Of the selection, 10 paintings were made around 1950, when the artist\'s work underwent a major transformation, from figuration to abstraction, from the use of industrial oil-based paints to the medieval technique of tempera. This technique, known for its opacity, colour saturation and material presence of pigments on the canvas,became as important as the colour itself in the shaping of the artist\'s new spatial relation. It is understood that these elements are important keys to a deeper understanding of his work, both technically and artistically. The present investigation was carried out making use of non-destructive complementary analytical techniques. The aim was to study the chromatic and chemical composition characteristics of his paintings and gather information on the technical procedures the artist may have used. The spectrophotometer was used to measure the colour based on the spectral curves and numerical reference coordinates within a uniform colour space. Techniques of visual examination with visible light, visible fluorescence by ultraviolet radiation and near-infrared reflectography were used to gather information about the artist\'s creative process. These techniques also helped detect restoration patches and identify pigments. The EDXRF (Energy Dispersive X-Ray Fluorescence) technique was important for chemical characterization of materials, while the SEM-EDS (Scanning Electron Microscope with Energy Dispersive X-Ray Spectroscopy) provided surface images and information on the chemical composition of the material present in the murals. From the integration of these techniques it was possible to identify a part of the rich palette of Volpi´s paintings; to document the present aspects of the colours; to recognize or give indications of pigment and ground compositions and to shed light on parts of each of the works background, such as the presence of graphite sketches, covered earlier paintings and brushstrokes as well as to document the current condition of the works under study. The tools used have proven useful in characterizing the paintings, revealing new information about the work of the artist and raising new questions. The information obtained may be the beginning of a database on his oeuvre.

La spectroscopie de réflectance diffuse dans le domaine du visible est une technique paradoxalement rarement utilisée pour identifier les matériaux des couches picturales des oeuvres d'art. Quand elle est malgré tout mise en oeuvre, l'identification de pigments à partir de ce type de mesures repose toujours sur la comparaison avec une base de données spectrophotométriques de pigments de référence. Au sein du Centre de Recherche et de Restauration des Musées de France, la base de données est composée des spectres de réflectance de pigments purs, secs et en poudre. Une couche picturale est au contraire constituée de pigments parfois mélangés et dispersés dans un liant. Ces deux caractéristiques des couches picturales ont permis de distinguer deux axes de recherche pour le travail de thèse. I. La caractérisation des mélanges de pigments La modélisation de Kubelka-Munk s'est avérée pertinente pour la gamme usuelle des couleurs utilisées dans les oeuvres d'art, et ce même dans le cas extrême des mélanges dans lesquels un des composants est nettement minoritaire. Il est à présent possible, pour un mélange binaire, de déterminer les composants du mélange dans la majorité des cas par traitement numérique des mesures spectrophotométriques. Une fois la nature des composants déterminée, il est de plus systématiquement possible d'en retrouver les proportions relatives. Les résultats obtenus sur les échantillons modèles ont pu être adaptés au cas d'une oeuvre d'art : la Vierge d'Annonciation attribuée à Giovanni di Paolo. Dans ce tableau italien du XVe siècle, la couleur du visage est réalisée à partir d'un mélange de blanc de plomb et de vermillon a tempera. Les proportions relatives calculées de ces deux pigments sont en accord avec ce qui est observable au microscope optique sur des prélèvements et mesurable ensuite par traitement des images. II. L'influence du liant Des échantillons de couches picturales ont été réalisés par un artiste selon une recette traditionnelle. La concentration de pigments et le nombre de couches de matière picturales varient selon les échantillons. Ces derniers ont été étudiés parallèlement en spectrophotométrie, en diffractométrie des rayons X et en microfluorimétrie X. Les résultats obtenus par ces méthodes d'analyse concordent. La méthode de Rietveld d'affinement des diffractogrammes permet notamment d'aboutir à des valeurs de concentration de pigment dans le liant tout à fait en accord avec les résultats obtenus par la modélisation de la propagation de la lumière dans les milieux absorbants et diffusants utilisée pour interpréter les mesures spectrophotométriques. L'aboutissement de ce travail de thèse devrait permettre aux scientifiques de la conservation, aux historiens d'art et aux restaurateurs d'envisager la spectrophotométrie comme une technique d'analyse qualitative et quantitative, sans prélèvement, sans contact et réalisable in situ, qui fournit la nature et les proportions des différents constituants de la matière picturale.

Parmi les disciplines représentatives de la biostructure, la cryomicroscopie électronique permet, au travers de techniques adaptées, d'atteindre de hautes résolutions. Mon travail a porté sur l'étude d'une catégorie de molécules, les particules isolées à faible degré de symétrie et entre autres sur les pigments respiratoires extracellulaires tels que les hémocyanines de céphalopodes (Vampyroteuthis infernalis, Benthoctopus species, Sepia officinalis) et une hémoglobine d'annélide (Lumbricus terrestris). Une approche empirique a été retenue, et nous a permis de différencier les informations techniques et les données biologiques. Le premier but, basé sur l'utilisation d'un matériel biologique connu, était de travailler sur les techniques d'observation de l'échantillon, d'analyse des images, de reconstruction et de correction des structures. Le deuxième but était d'apporter des réponses de type biologique, par le biais de ces améliorations techniques. Le début de ma thèse fut lié à l'utilisation d'un microscope équipé d'un cristal de LaB6, ne permettant pas de descendre significativement sous la barre des 20 Å. Néanmoins, il nous a permis de répondre à une question de type phylogénétique (Benthoctopus species et Vampyroteuthis infernalis appartiennent à des ordres frères), et de démontrer l'importance du type de microscope et de la source électronique associée. Naturellement, l'étape suivante fut d'accéder à un microscope équipé d'un canon à émission de champ. L'accès sporadique et sur de courtes périodes à ce type de microscope, dont les premiers exemplaires sont arrivés en France en 2000, ne m'ont pas permis de tester systématiquement tous les modes d'utilisation. Malgré tout, les résultats que nous avons obtenu ont validé les avantages de l'émission de champ. Certes, la barre des 6-7 Å de résolution, donnant partiellement accès aux informations relatives à la structure secondaire des protéines, n'a pas encore été atteinte, mais il apparaît que les progrès que nous avons effectués tendent vers cette valeur. Cette progression repose en partie sur l'amélioration des méthodes de collecte des images, de reconstruction et de correction de la fonction de transfert de contraste.