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Liu, Yan. "Negative feedback control of the visual system and systematic colors vision model /." Online version of thesis, 1991. http://hdl.handle.net/1850/11211.
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Skaff, Sandra. "Spectral models for color vision." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66750.
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This thesis introduces a maximum entropy approach to model surface reflectance spectra. A reflectance spectrum is the amount of light, relative to the incident light, reflected from a surface at each wavelength. While the color of a surface can be in 3D vector form such as RGB, CMY, or YIQ, this thesis takes the surface reflectance spectrum to be the color of a surface. A reflectance spectrum is a physical property of a surface and does not vary with the different interactions a surface may undergo with its environment. Therefore, models of reflectance spectra can be used to fuse camera sensor responses from different images of the same surface or multiple surfaces of the same scene. This fusion improves the spectral estimates that can be obtained, and thus leads to better estimates of surface colors. The motivation for using a maximum entropy approach stems from the fact that surfaces observed in our everyday life surroundings typically have broad and therefore high entropy spectra. The maximum entropy approach, in addition, imposes the fewest constraints as it estimates surface reflectance spectra given only camera sensor responses. This is a major advantage over the widely used linear basis function spectral representations, which require a prespecified set of basis functions. Experimental results show that surface spectra of Munsell and construction paper patches can be successfully estimated using the maximum entropy approach in the case of three different surface interactions with the environment. First, in the case of changes in illumination, the thesis shows that the spectral models estimated are comparable to those obtained from the best approach which computes spectral models in the literature. Second, in the case of changes in the positions of surfaces with respect to each other, interreflections between the surfaces arise. Results show that the fusion of sensor responses from interreflectionCette thèse introduit une approche par entropie maximale pour la modélisation des spectres de réflectance de surface. Un spectre de réflectance est la quantité de lumière, relative à la lumière incidente, réfléchie d'une surface à chaque longueur d'onde. Bien que la couleur d'une surface puisse prendre la forme d'un vecteur 3D tel que RGB, CMY ou YIQ, cette thèse prend le spectre de réflectance de surface comme étant la couleur d'une surface. Un spectre de réflectance est une propriété physique d'une surface et ne varie pas avec les différentes interactions que peut subir une surface avec son environnement. Par conséquent, les modèles de spectres de réflectance peuvent être utilisés pour fusionner les réponses de senseurs de caméra provenant de différentes images d'une même surface ou de multiples surfaces de la même scène. Cette fusion améliore les estimés spectraux qui peuvent être obtenus et mène donc à de meilleurs estimés de couleurs de surfaces.La motivation pour l'utilisation d'une approche par entropie maximale provient du fait que les surfaces observées dans notre environnement habituel ont typiquement un spectre large et donc à haute entropie. De plus, l'approche par entropie maximale impose le moins de contraintes puisqu'elle estime les spectres de réflectance de surface à l'aide seulement des réponses de senseurs de caméra. Ceci est un avantage majeur par rapport aux très répandues représentations spectrales par fonctions de base linéaires qui requièrent une série pré-spécifiée de fonctions de base.Les résultats expérimentaux montrent que les spectres de surface de taches de surface de Munsell et de papier de construction peuvent être estimés avec succès en utilisant l'approche par entropie maximal dans le cas de trois différentes interactions de surfaces avec l'environnement. D'abord, dans le cas de changements dans l'illumination, la t
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Shayeghpour, Omid. "Improving information perception from digital images for users with dichromatic color vision." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-101984.
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Color vision deficiency (CVD) is the inability or limited ability to recognize colors and discriminate between them. A person with this condition perceives a narrower range of colors compared to a person with a normal color vision. A growing number of researchers are striving to improve the quality of life for CVD patients. Finding cure, making rectification equipment, providing simulation tools and applying color transformation methods are among the efforts being made by researchers in this field. In this study we concentrate on recoloring digital images in such a way that users with CVD, especially dichromats, perceive more details from the recolored images compared to the original image. The main focus is to give the CVD user a chance to find information within the picture which they could not perceive before. However, this transformed image might look strange or unnatural to users with normal color vision. During this color transformation process, the goal is to keep the overall contrast of the image constant while adjusting the colors that might cause confusion for the CVD user. First, each pixel in the RGB-image is converted to HSV color space in order to be able to control hue, saturation and intensity for each pixel and then safe and problematic hue ranges need to be found. The method for recognizing these ranges was inspired by a condition called “unilateral dichromacy” in which the patient has normal color vision in one eye and dichromacy in another. A special grid-like color card is designed, having constant saturation and intensity over the entire image, while the hue smoothly changes from one block to another to cover the entire hue range. The next step is to simulate the way this color card is perceived by a dichromatic user and finally to find the colors that are perceived identically from two images and the ones that differ too much. This part makes our method highly customizable and we can apply it to other types of CVD, even personalize it for the color vision of a specific observer. The resulting problematic colors need to be dealt with by shifting the hue or saturation based on some pre-defined rules. The results for the method have been evaluated both objectively and subjectively. First, we simulated a set of images as they would be perceived by a dichromat and compared them with simulated view of our transformed images. The results clearly show that our recolored images can eliminate a lot of confusion from user and convey more details. Moreover, an online questionnaire was created and 39 users with CVD confirmed that the transformed images allow them to perceive more information compared to the original images.
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Lau, Hoi Ying. "Neural inspired color constancy model based on double opponent neurons /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20LAU.
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Machado, Gustavo Mello. "A model for simulation of color vision deficiency and a color contrast enhancement technique for dichromats." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/26950.
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As Deficiências na Percepção de Cores (DPC) afetam aproximadamente 200 milhões de pessoas em todo o mundo, comprometendo suas habilidades para efetivamente realizar tarefas relacionadas com cores e com visualização. Isto impacta significantemente os âmbitos pessoais e profissionais de suas vidas. Este trabalho apresenta um modelo baseado na fisiologia para simulação da percepção de cores. Além de modelar visão de cores normal, ele também compreende os tipos mais predominantes de deficiências na visão de cores (i.e., protanopia, deuteranopia, protanomalia e deuteranomalia), cujas causas são hereditárias. Juntos estes representam aproximadamente 99.96% de todos os casos de DPC. Para modelar a percepção de cores da visão humana, este modelo é baseado na teoria dos estágios e é derivado de dados reportados em estudos eletrofisiológicos. Ele é o primeiro modelo a consistentemente tratar visão de cores normal, tricromacia anômala e dicromacia de modo unificados. Seus resultados foram validados por avaliações experimentais envolvendo grupos de indivíduos com deficiência na percepção de cores e outros com visão de cores normal. Além disso, ele pode proporcionar a melhor compreensão e um feedback sobre como aperfeiçoar as experiências de visualização por indivíduos com DPC. Ele também proporciona um framework para se testar hipóteses sobre alguns aspectos acerca das células fotoreceptoras na retina de indivíduos com deficiência na percepção de cores. Este trabalho também apresenta uma técnica automática de recoloração de imagens que visa realçar o contraste de cores para indivíduos dicromatas com custo computacional variando linearmente com o número de pixels. O algoritmo proposto pode ser eficientemente implementado em GPUs, e para imagens com tamanhos tipicos ele apresenta performance de até duas ordens de magnitude mais rápida do que as técnicas estado da arte atuais. Ao contrário das abordagens anteriores, a técnica proposta preserva coerência temporal e, portanto, é adequado para recoloração de vídeos. Este trabalho demonstra a efetividade da técnica proposta ao integrá-la a um sistema de visualização e apresentando, pela primeira vez, cenas de visualização recoloridas para dicromatas em tempo-real e com alta qualidade.Color vision deficiency (CVD) affects approximately 200 million people worldwide, compromising the ability of these individuals to effectively perform color and visualizationrelated tasks. This has a significant impact on their private and professional lives. This thesis presents a physiologically-based model for simulating color perception. Besides modeling normal color vision, it also accounts for the hereditary and most prevalent cases of color vision deficiency (i.e., protanopia, deuteranopia, protanomaly, and deuteranomaly), which together account for approximately 99.96% of all CVD cases. This model is based on the stage theory of human color vision and is derived from data reported in electrophysiological studies. It is the first model to consistently handle normal color vision, anomalous trichromacy, and dichromacy in a unified way. The proposed model was validated through an experimental evaluation involving groups of color vision deficient individuals and normal color vision ones. This model can provide insights and feedback on how to improve visualization experiences for individuals with CVD. It also provides a framework for testing hypotheses about some aspects of the retinal photoreceptors in color vision deficient individuals. This thesis also presents an automatic image-recoloring technique for enhancing color contrast for dichromats whose computational cost varies linearly with the number of input pixels. This approach can be efficiently implemented on GPUs, and for typical image sizes it is up to two orders of magnitude faster than the current state-of-the-art technique. Unlike previous approaches, the proposed technique preserves temporal coherence and, therefore, is suitable for video recoloring. This thesis demonstrates the effectiveness of the proposed technique by integrating it into a visualization system and showing, for the first time, real-time high-quality recolored visualizations for dichromats.
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Kim, Taek Gyu. "Comparing color appearance models using pictorial images /." Online version of thesis, 1994. http://hdl.handle.net/1850/11756.
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Spencer, Lisa. "REAL-TIME MONOCULAR VISION-BASED TRACKING FOR INTERACTIVE AUGMENTED REALITY." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4289.
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The need for real-time video analysis is rapidly increasing in today's world. The decreasing cost of powerful processors and the proliferation of affordable cameras, combined with needs for security, methods for searching the growing collection of video data, and an appetite for high-tech entertainment, have produced an environment where video processing is utilized for a wide variety of applications. Tracking is an element in many of these applications, for purposes like detecting anomalous behavior, classifying video clips, and measuring athletic performance. In this dissertation we focus on augmented reality, but the methods and conclusions are applicable to a wide variety of other areas. In particular, our work deals with achieving real-time performance while tracking with augmented reality systems using a minimum set of commercial hardware. We have built prototypes that use both existing technologies and new algorithms we have developed. While performance improvements would be possible with additional hardware, such as multiple cameras or parallel processors, we have concentrated on getting the most performance with the least equipment. Tracking is a broad research area, but an essential component of an augmented reality system. Tracking of some sort is needed to determine the location of scene augmentation. First, we investigated the effects of illumination on the pixel values recorded by a color video camera. We used the results to track a simple solid-colored object in our first augmented reality application. Our second augmented reality application tracks complex non-rigid objects, namely human faces. In the color experiment, we studied the effects of illumination on the color values recorded by a real camera. Human perception is important for many applications, but our focus is on the RGB values available to tracking algorithms. Since the lighting in most environments where video monitoring is done is close to white, (e.g., fluorescent lights in an office, incandescent lights in a home, or direct and indirect sunlight outside,) we looked at the response to "white" light sources as the intensity varied. The red, green, and blue values recorded by the camera can be converted to a number of other color spaces which have been shown to be invariant to various lighting conditions, including view angle, light angle, light intensity, or light color, using models of the physical properties of reflection. Our experiments show how well these derived quantities actually remained constant with real materials, real lights, and real cameras, while still retaining the ability to discriminate between different colors. This color experiment enabled us to find color spaces that were more invariant to changes in illumination intensity than the ones traditionally used. The first augmented reality application tracks a solid colored rectangle and replaces the rectangle with an image, so it appears that the subject is holding a picture instead. Tracking this simple shape is both easy and hard; easy because of the single color and the shape that can be represented by four points or four lines, and hard because there are fewer features available and the color is affected by illumination changes. Many algorithms for tracking fixed shapes do not run in real time or require rich feature sets. We have created a tracking method for simple solid colored objects that uses color and edge information and is fast enough for real-time operation. We also demonstrate a fast deinterlacing method to avoid "tearing" of fast moving edges when recorded by an interlaced camera, and optimization techniques that usually achieved a speedup of about 10 from an implementation that already used optimized image processing library routines. Human faces are complex objects that differ between individuals and undergo non-rigid transformations. Our second augmented reality application detects faces, determines their initial pose, and then tracks changes in real time. The results are displayed as virtual objects overlaid on the real video image. We used existing algorithms for motion detection and face detection. We present a novel method for determining the initial face pose in real time using symmetry. Our face tracking uses existing point tracking methods as well as extensions to Active Appearance Models (AAMs). We also give a new method for integrating detection and tracking data and leveraging the temporal coherence in video data to mitigate the false positive detections. While many face tracking applications assume exactly one face is in the image, our techniques can handle any number of faces. The color experiment along with the two augmented reality applications provide improvements in understanding the effects of illumination intensity changes on recorded colors, as well as better real-time methods for detection and tracking of solid shapes and human faces for augmented reality. These techniques can be applied to other real-time video analysis tasks, such as surveillance and video analysis.Ph.D.
School of Computer Science
Engineering and Computer Science
Computer Science
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Jeong, Kideog. "OBJECT MATCHING IN DISJOINT CAMERAS USING A COLOR TRANSFER APPROACH." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/434.
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Object appearance models are a consequence of illumination, viewing direction, camera intrinsics, and other conditions that are specific to a particular camera. As a result, a model acquired in one view is often inappropriate for use in other viewpoints. In this work we treat this appearance model distortion between two non-overlapping cameras as one in which some unknown color transfer function warps a known appearance model from one view to another. We demonstrate how to recover this function in the case where the distortion function is approximated as general affine and object appearance is represented as a mixture of Gaussians. Appearance models are brought into correspondence by searching for a bijection function that best minimizes an entropic metric for model dissimilarity. These correspondences lead to a solution for the transfer function that brings the parameters of the models into alignment in the UV chromaticity plane. Finally, a set of these transfer functions acquired from a collection of object pairs are generalized to a single camera-pair-specific transfer function via robust fitting. We demonstrate the method in the context of a video surveillance network and show that recognition of subjects in disjoint views can be significantly improved using the new color transfer approach.
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Pirrotta, Elizabeth. "Testing chromatic adaptation models using object colors /." Online version of thesis, 1994. http://hdl.handle.net/1850/11674.
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Zapata, Iván R. "Detecting humans in video sequences using statistical color and shape models." [Gainesville, Fla.] : University of Florida, 2001. http://etd.fcla.edu/etd/uf/2001/anp1058/ivan%5Fthesis2.pdf.
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Thesis (M.S.)--University of Florida, 2001.Title from first page of PDF file. Document formatted into pages; contains viii, 49 p.; also contains graphics. Vita. Includes bibliographical references (p. 47-48).
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Gerstley, Lawrence D. "Cross-modal and synaesthetic perception in music and vision." Thesis, University of Stirling, 1997. http://hdl.handle.net/1893/2223.
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This thesis is concerned with the cross-modal and synaesthetic perception of musical and visual stimuli. Each of these types of perception has been researched separately, and a hypothesis is presented here that accounts for both cross-modal matching and the development of synaesthesia. This hypothesis claims that sensory information can be evaluated in another modality by using a scale of comparison in that modality. The first set of experiments examines normal subjects performing cross-modal matching with coloured circles and auditory stimuli that vary in complexity. It is shown that subjects use a variety of scales of comparison from both visual and auditory modalities to form matches. As the stimuli increase in complexity, the individual variation in cross-modal matching also increases. The second set of experiments examines matching performance using higher order stimuli, by having subjects evaluate fragments of melodies and complete melodies on affective and descriptive adjective scales. Melodies were also matched with landscape scenes to examine if subjects could form matches between two highly complex sets of stimuli. The final experiments examine synaesthetic associations with colour, evoked from music, letters, numbers, and other categorical information. Common features of synaesthesia from a population of synaesthetes are identified, and experiments performed to test the interference of the synaesthetic associations. Additional experiments are presented that explore the superior short-term memory of one synaesthete, and the role of his associations as a mnemonic device.
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Daley, Wayne D. R. "A Methodology for the Development of Machine Vision Algorithms Through the use of Human Visual Models." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4996.
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The development of machine vision algorithms for inspection and machine guidance has traditionally relied on the knowledge and experience of the developers as most of the techniques are based on heuristics and trial and error. This is especially problematic in the area of natural products where variability of the products is the rule rather than the exception. Humans are particularly good in functioning in this arena and in this thesis we look at the development of techniques derived from the functions of the human visual system (HVS). We first identify the significant processes in the HVS and highlight those that we believe are germane to the problems of interest. We then develop computational techniques using these methods and demonstrate their applicability to practical problems.
This thesis uses the knowledge that the HVS is considered to consist of three sequential operations (sensing; encoding/transfer; and image interpretation) as a basis for developing a parallel procedure for a machine vision system. We have found that outputs derived from a simulation of the behaviors of receptive fields in the retina and in the higher levels of the brain can generate useful and robust features. Equivalent processes are then developed for machine applications under the guidance of a human operator to identify the areas of interest in the scene for the problem under consideration. Specifically we use the processes for encoding/transfer of data from the retina to develop techniques to enhance color contrasts, and compute color image features that are useful for defect detection and identification in real world images. This is accomplished by a transformation from image space to a characteristic response space that improves the robustness of classification.
In this thesis the approach developed is applied to two industrial problems in the quality monitoring of meat and vegetables. The first problem concerns the quality monitoring of breast butterflies and the other the detection of defects on the surface of citrus. The approach is shown to derive algorithms that are robust and can be implemented at high rates of speed. Additionally we also identify a model within which further developments can be conducted as we learn more about the functioning of the HVS.
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Talebzadeh, Shahrbabaki Shahrbanoo. "Contribution of colour in guiding visual attention and in a computational model of visual saliency." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT093/document.
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Les études menées dans cette thèse portent sur le rôle de la couleur dans l'attention visuelle. Nous avons tenté de comprendre l'influence de l'information couleur dans les vidéos sur les mouvements oculaire, afin d'intégrer les attributs couleur dans un modèle de saillance visuelle. Pour cela, nous avons analysé différentes caractéristiques des mouvements oculaires d'observateurs regardant librement des vidéos en deux conditions: couleur et niveaux de gris. Nous avons également comparé les régions principales de regard sur des vidéos en couleur avec celles en niveaux de gris. Il est apparu que les informations de couleur modifient légèrement les caractéristiques de mouvement oculaire comme la position de l'œil et la durée des fixations. Cependant, nous avons constaté que la couleur augmente le nombre de régions de regard. De plus, cet influence de la couleur s'accroît au cours du temps. En nous appuyant sur ces résultats, nous avons proposé une méthode de calcul des cartes de saillance couleur. Nous avons intégré ces cartes dans un modèle de saillance existantThe studies conducted in this thesis focus on the role of colour in visual attention. We tried to understand the influence of colour information on the eye movements while observing videos, to incorporate colour information into a model of visual saliency. For this, we analysed different characteristics of eye movements of observers while freely watching videos in two conditions: colour and grayscale videos. We also have compared the main regions of regard of colour videos with those of grayscale. We observed that colour information influences only moderately, the eye movement characteristics such as the position of gaze and duration of fixations. However, we found that colour increases the number of the regions of interest in video stimuli. Moreover, this varies across time. Based on these observations, we proposed a method to compute colour saliency maps for videos. We have incorporated colour saliency maps in an existing model of saliency
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Lessios, Nicolas. "Using electroretinograms and multi-model inference to identify spectral classes of photoreceptors and relative opsin expression levels." PEERJ INC, 2017. http://hdl.handle.net/10150/625519.
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Understanding how individual photoreceptor cells factor in the spectral sensitivity of a visual system is essential to explain how they contribute to the visual ecology of the animal in question. Existing methods that model the absorption of visual pigments use templates which correspond closely to data from thin cross-sections of photoreceptor cells. However, few modeling approaches use a single framework to incorporate physical parameters of real photoreceptors, which can be fused, and can form vertical tiers. Akaike’s information criterion (AIC
c
) was used here to select absorptance models of multiple classes of photoreceptor cells that maximize information, given visual system spectral sensitivity data obtained using extracellular electroretinograms and structural parameters obtained by histological methods. This framework was first used to select among alternative hypotheses of photoreceptor number. It identified spectral classes from a range of dark-adapted visual systems which have between one and four spectral photoreceptor classes. These were the velvet worm,
Principapillatus hitoyensis
, the branchiopod water flea,
Daphnia magna
, normal humans, and humans with enhanced S-cone syndrome, a condition in which S-cone frequency is increased due to mutations in a transcription factor that controls photoreceptor expression. Data from the Asian swallowtail,
Papilio xuthus
, which has at least five main spectral photoreceptor classes in its compound eyes, were included to illustrate potential effects of model over-simplification on multi-model inference. The multi-model framework was then used with parameters of spectral photoreceptor classes and the structural photoreceptor array kept constant. The goal was to map relative opsin expression to visual pigment concentration. It identified relative opsin expression differences for two populations of the bluefin killifish,
Lucania goodei
. The modeling approach presented here will be useful in selecting the most likely alternative hypotheses of opsin-based spectral photoreceptor classes, using relative opsin expression and extracellular electroretinography.
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Beigpour, Shida. "Illumination and Object Reflectance Modeling." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/113551.
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El modelado de la reflectancia de las superficies es una clave importante para la comprensión de escenas. Un modelo de reflectancia preciso, basado en las leyes de la física, nos permite alcanzar resultados realísticos y físicamente plausibles. Además, el uso de tal modelo nos permite establecer un conocimiento más profundo acerca de la interacción de la luz con las superficies de los objetos, y resulta crucial para una variedad de aplicaciones de visión por computador. Debido a la alta complejidad de los modelos de reflectancia, la gran mayoría de las aplicaciones existentes de visión por computador basan sus métodos en suposiciones simplificadoras, tales como la reflectancia lambertiana o la iluminación uniforme para ser capaz de resolver sus problemas.
Sin embargo, en escenas del mundo real, los objetos tienden a exhibir reflexiones más complejas (difusas y especulares), y además se ven afectados por las características y la cromaticidad de los iluminantes. En esta tesis, se incorpora un modelo de reflexión más realista para aplicaciones de visión por computador.
Para abordar tal fenómeno físico complejo, extendemos los modelos de reflectancia de los objetos del estado-del-arte mediante la introducción de un Modelo de Reflexión Dicromático Multi-Iluminante (MIDR). Usando MIDR somos capaces de modelar y descomponer la reflectancia de un objeto con especularidades complejas bajo múltiples iluminantes que presentan sombras e interreflexiones. Se demuestra que este modelo nos permite realizar una recolorización realista de los objetos iluminados por luces de colores y múltiples iluminantes.
Además se propone un método "local" de estimación del iluminante para modelar las escenas con iluminación no uniforme (por ejemplo, una escena al aire libre con un cielo azul y un sol amarillo, una escena interior con iluminación combinada con la iluminación al aire libre a través de una ventana, o cualquier otro caso en el que dos o más luces con diferentes colores iluminan diferentes partes de la escena). El método propuesto aprovecha un modelo probabilístico basado en grafos y resuelve el problema rededefiniendo la estimación como un problema de minimización de energía. Este método nos proporciona estimaciones locales del iluminante que mejoran en gran medida a los métodos del estado-del-arte en constancia de color.
Por otra parte, hemos capturado nuestro propia base de datos multi-iluminante, que consiste de escenas complejas y condiciones de iluminación al aire libre o de laboratorio. Con ésta se demuestra la mejora lograda usando nuestro método con respecto a los métodos del estado-del-arte para la estimación automática del iluminante local.
Se demuestra que tener un modelo más realista y preciso de la iluminación de la escena y la reflectancia de los objetos, mejora en gran medida la calidad en muchas tareas de visión por ordenador y gráficos por computador. Mostramos ejemplos de mejora en el balance automático de blanco, reiluminación de escenas y en la recolorización de objetos. La teoría propuesta se puede emplear también para mejorar la denominación automática de colores, la detección de objetos, el reconocimiento y la segmentación, que están entre las tendencias más populares de la visión por computador.Surface reflectance modeling is an important key to scene understanding. An accurate reflectance model which is based on the laws of physics allows us to achieve realistic and physically plausible results. Using such model, a more profound knowledge about the interaction of light with objects surfaces can be established which proves crucial to variety of computer vision application. Due to high complexity of the reflectance model, the vast majority of the existing computer vision applications base their methods on simplifying assumptions such as Lambertian reflectance or uniform illumination to be able to solve their problem. However, in real world scenes, objects tend to exhibit more complex reflections (diffuse and specular) and are furthermore affected by the characteristics and chromaticity of the illuminants. In this thesis, we incorporate a more realistic reflection model in computer vision applications. To address such complex physical phenomenon, we extend the state-of-the-art object reflectance models by introducing a Multi-Illuminant Dichromatic Reflection model (MIDR). Using MIDR we are able to model and decompose the reflectance of an object with complex specularities under multiple illuminants presenting shadows and inter-reflections. We show that this permits us to perform realistic re-coloring of objects lit by colored lights, and multiple illuminants. Furthermore, we propose a “local” illuminant estimation method in order to model the scenes with non-uniform illumination (e.g., an outdoor scene with a blue sky and a yellow sun, a scene with indoor lighting combined with outdoor lighting through a window, or any other case in which two or more lights with distinct colors illuminating different parts of the scene). The proposed method takes advantage of a probabilistic and graph-based model and solves the problem by re-defining the estimation problem as an energy minimization. This method provides us with local illuminant estimations which improve greatly over state-of-the-art color constancy methods. Moreover, we captured our own multi-illuminant dataset which consists of complex scenes and illumination conditions both outdoor and in laboratory conditions. We show improvement achieved using our method over state-of-the-art methods for local illuminant estimation. We demonstrate that having a more realistic and accurate model of the scene illumination and object reflectance greatly improves the quality of many computer vision and computer graphics tasks. We show examples of improved automatic white balance, scene relighting, and object re-coloring. The proposed theory can be employed in order to improve color naming, object detection, recognition, and segmentation which are among the most popular computer vision trends.
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Ylimäki, M. (Markus). "Methods for image-based 3-D modeling using color and depth cameras." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526217352.
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Abstract This work addresses the problems related to three-dimensional modeling of scenes and objects and model evaluation. The work is divided into four main parts. At first, the work concentrates on purely image-based reconstruction while the second part presents a modeling pipeline based on an active depth sensor. Then, the work introduces methods for producing surface meshes from point clouds, and finally, a novel approach for model evaluation is presented. In the first part, this work proposes a multi-view stereo (MVS) reconstruction method that takes a set of images as an input and outputs a model represented as a point cloud. The method is based on match propagation, where a set of initial corresponding points between images is expanded iteratively into larger regions by searching new correspondences in the spatial neighborhood of the existing ones. The expansion is implemented using a best-first strategy, where the most reliable match is always expanded first. The method produces comparable results with the state-of-the-art but significantly faster. In the second part, this work presents a method that merges a sequence of depth maps into a single non-redundant point cloud. In the areas, where the depth maps overlap, the method fuses points together by giving more weight to points which seem to be more reliable. The method overcomes its predecessor both in accuracy and robustness. In addition, this part introduces a method for depth camera calibration. The method develops on an existing calibration approach which was originally designed for the first generation Microsoft Kinect device. The third part of the thesis addresses the problem of converting the point clouds to surface meshes. The work briefly reviews two well-known approaches and compares their ability to produce sparse mesh models without sacrificing accuracy. Finally, the fourth part of this work describes the development of a novel approach for performance evaluation of reconstruction algorithms. In addition to the accuracy and completeness, which are the metrics commonly used in existing evaluation benchmarks, the method also takes the compactness of the models into account. The metric enables the evaluation of the accuracy-compactness trade-off of the modelsTiivistelmä Tässä työssä käsitellään näkymän tai esineen kolmiulotteista mallintamista ja tulosten laadun arviointia. Työ on jaettu neljään osaan. Ensiksi keskitytään pelkästään valokuvia hyödyntävään mallinnukseen ja sitten esitellään menetelmä syvyyskamerapohjaiseen mallinnukseen. Kolmas osa kuvaa menetelmiä verkkomallien luomiseen pistepilvestä ja lopuksi esitellään menetelmä mallien laadun arviointiin. Ensimmäisessä osassa esitellään usean kuvan stereoon perustuva mallinnusmenetelmä, joka saa syötteenä joukon valokuvia ja tuottaa kuvissa näkyvästä kohteesta pistepilvimallin. Menetelmä perustuu vastinpisteiden laajennukseen, jossa kuvien välisiä pistevastaavuuksia laajennetaan iteratiivisesti suuremmiksi vastinalueiksi hakemalla uusia vastinpistepareja jo löydettyjen läheisyydestä. Laajennus käyttää paras ensin -menetelmää, jossa luotettavin pistevastaavuus laajennetaan aina ensin. Menetelmä tuottaa vertailukelpoisia tuloksia johtaviin menetelmiin verrattuna, mutta merkittävästi nopeammin. Toisessa osassa esitellään menetelmä, joka yhdistää joukon syvyyskameralla kaapattuja syvyyskarttoja yhdeksi pistepilveksi. Alueilla, jotka sisältävät syvyysmittauksia useasta syvyyskartasta, päällekkäiset mittaukset yhdistetään painottamalla luotettavammalta vaikuttavaa mittausta. Menetelmä on tarkempi kuin edeltäjänsä ja toimii paremmin kohinaisemmalla datalla. Lisäksi tässä osassa esitellään menetelmä syvyyskameran kalibrointiin. Menetelmä kehittää jo olemassa olevaa kalibrointityökalua, joka alun perin kehitettiin ensimmäisen sukupolven Microsoft Kinect laitteelle. Väitöskirjan kolmas osa käsittelee pintamallin luomista pistepilvestä. Työ esittelee kaksi hyvin tunnettua menetelmää ja vertailee niiden kykyä luoda harvoja, mutta edelleen tarkkoja malleja. Lopuksi esitellään uudenlainen menetelmä mallinnusmenetelmien arviointiin. Tarkkuuden ja kattavuuden lisäksi, jotka ovat yleisimmät arvioinnissa käytetyt metriikat, menetelmä ottaa huomioon myös mallin pistetiheyden. Metriikan avulla on mahdollista arvioida kompromissia mallin tarkkuuden ja tiheyden välillä
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Faruq, Samia. "Comparing the efficiency of computational colour constancy algorithms in agent-based simulations : flower colours and pollinators as a model." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8476.
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The perceived colour of an object depends on its spectral reflection and spectral composition of the illuminant. Upon illumination change, the light reflected from the object also varies. This results in a different colour sensation if no colour constancy mechanism is available to form consistent representations of colours across various illuminants. We explore various colour constancy mechanisms in an agent-based model of foraging bees selecting flower colour based on reward. The simulations are based on empirically determined spatial distributions of various flower species in different plant communities, their rewards and spectral reflectance properties. Simulated foraging bees memorise the colours of flowers experienced as being most rewarding, and their task is to discriminate against other flower colours with lower rewards, even in the face of changing illumination conditions. The experimental setup of the simulation of bees foraging under different photic environments reveals the performance of various colour constancy mechanisms as well as the selective pressures on flower colour as a result of changing light. We compared the performance of von Kries photoreceptor adaptation and various computational colour constancy models based on the retinex theory with (hypothetical) bees with perfect colour constancy, and with modelled bees with colour blindness. While each individual model generated moderate improvements over a colour-blind bee, the most powerful recovery of reflectance in the face of changing illumination was generated by computational mechanisms that increase perceptual distances between co-occurring colours in the scene. We verified the results of our model using various comparisons between modelled bees’ performance and that predicted by our models, as well as exploring the implications for flower colour distribution in a variety of representative habitats under realistic illumination conditions.
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Akbarinia, SeyedArash. "Computational model of visual perception: from colour to form." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/457882.
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La idea original de este proyecto fue estudiar la importancia del color en el reconocimiento de objetos. Comenzamos extendiendo la investigación previa sobre nombrar colores y demostrando la viabilidad de capturar términos de color a través de elipsoides. Aunque nuestros resultados superaron el estado-del-arte en dos bases de datos, vimos que los fenómenos de luces metaméricas y constancia de color debían ser tratados antes de cualquier procesamiento de color. Nuestra investigación de pares metaméricas mostró que son infrecuentes en el mundo real. Contrariamente a eso, la iluminación de una escena a menudo cambia drásticamente. Abordamos este problema proponiendo un modelo de constancia de color inspirado en la adaptación dinámica del centro-envolvente de las neuronas en la corteza visual. Esto se implementa a través de dos gaussianos asimétricos superpuestos, cuyas varianzas y alturas se ajustan al contraste local. Complementamos este modelo con un mecanismo genérico de agrupación variante por contraste que inversamente conecta el porcentaje de señal agrupada al contraste de una región. Los resultados sobre cuatro bases de datos fueron prometedores: nuestro modelo superó incluso los enfoques basados en el aprendizaje en muchos casos. Alentados por el éxito obtenido, ampliamos este enfoque para detectar los bordes de los objetos. Proponemos un modelo de detección de bordes basado en la primera derivada del kernel gaussiano. Incorporamos cuatro tipos de envolvente: completa, distante, orientación isogonal y ortogonal. Además, contamos con el mecanismo de agrupación en las áreas corticales superiores y la retroalimentación de la forma enviada a las zonas más bajas. Nuestros resultados en tres bases de datos mejoraron el estado-del-arte en los algoritmos sin aprendizaje.
En resumen, hemos demostrado que los modelos inspirados biológicamente ofrecen soluciones para visión por computador, como nombrar colores, constancia de color y detección de bordes. Creemos que la mayor contribución de esta tesis doctoral es el modelado del concepto de modulación envolvente dinámica que muestra la importancia de la integración de envolvente variante por contraste. Los modelos propuestos se basan en sólo una parte de lo que sabemos sobre la visión humana. Por lo tanto, es natural complementarlos en trabajos futuros.La idea original d'aquest projecte va ser estudiar la importància del color al reconeixement d'objectes. Comencem estenent la investigació prèvia sobre l’anomenament de colors i demostrant la viabilitat de capturar termes de color a través d’el·lipsoides. Tot i que els nostres resultats van superar l'estat de l’art utilitzant dues bases de dades, vam veure que els fenòmens de llums metamèriques i constància de color havien de ser tractats abans de qualsevol processament de color. Sobre la nostra investigació de parells metamèriques concloem que són infreqüents en el món real. Contràriament a això, la il·luminació d'una escena sovint canvia dràsticament. Abordem aquest problema proposant un model de constància de color inspirat en l'adaptació dinàmica del centre-envoltant de les neurones al còrtex visual. Això s'implementa a través de dues gaussianes asimètriques superposades, les variàncies i les alçades de les quals s'ajusten amb el contrast local dels píxels. Complementem aquest model amb un mecanisme genèric d'agrupació variant per contrast que connecta inversament el percentatge de senyal agrupada amb el contrast d'una regió. Els resultats sobre quatre bases de dades van ser prometedors: el model proposat superava, en molts casos, els models basats en aprenentatge. Encoratjats per l'èxit obtingut, ampliem aquesta proposta per detectar les vores dels objectes. Proposem un model de detecció de vores basat en la primera derivada del nucli gaussià. Incorporem quatre tipus de voltants: completa, distant, orientació isogonal i ortogonal. A més, comptem amb el mecanisme d'agrupació en les àrees corticals superiors i la retroalimentació de la forma, que és enviada a les zones més baixes. Els nostres resultats en tres bases de dades van millorar l'estat de l’art en els algoritmes sense aprenentatge. En resum, hem demostrat que els models biològicament inspirats ofereixen solucions per a visió per computador, com anomenament de colors, constància de color i detecció de vores. Creiem que la major contribució d'aquesta tesi doctoral és el modelatge del concepte de modulació envoltant dinàmica que mostra la importància de la integració de l’entorn que varia segons el contrast. Els models proposats es basen en una part del que sabem sobre la visió humana. Per tant, és natural complementar-los en treballs futurs.
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Bales, Michael Ryan. "Illumination compensation in video surveillance analysis." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39535.
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Problems in automated video surveillance analysis caused by illumination changes are explored, and solutions are presented. Controlled experiments are first conducted to measure the responses of color targets to changes in lighting intensity and spectrum. Surfaces of dissimilar color are found to respond significantly differently. Illumination compensation model error is reduced by 70% to 80% by individually optimizing model parameters for each distinct color region, and applying a model tuned for one region to a chromatically different region increases error by a factor of 15. A background model--called BigBackground--is presented to extract large, stable, chromatically self-similar background features by identifying the dominant colors in a scene. The stability and chromatic diversity of these features make them useful reference points for quantifying illumination changes. The model is observed to cover as much as 90% of a scene, and pixels belonging to the model are 20% more stable on average than non-member pixels. Several illumination compensation techniques are developed to exploit BigBackground, and are compared with several compensation techniques from the literature. Techniques are compared in terms of foreground / background classification, and are applied to an object tracking pipeline with kinematic and appearance-based correspondence mechanisms. Compared with other techniques, BigBackground-based techniques improve foreground classification by 25% to 43%, improve tracking accuracy by an average of 20%, and better preserve object appearance for appearance-based trackers. All algorithms are implemented in C or C++ to support the consideration of runtime performance. In terms of execution speed, the BigBackground-based illumination compensation technique is measured to run on par with the simplest compensation technique used for comparison, and consistently achieves twice the frame rate of the two next-fastest techniques.
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Alleysson, David. "Le traitement du signal chromatique dans la rétine : un modèle de base pour la percéption humaine des couleurs." Phd thesis, Université Joseph Fourier (Grenoble ; 1971-2015), 1999. http://www.theses.fr/1999GRE10037.
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La connaissance des principes et des mecanismes de la perception humaine de la couleur permet de mettre en uvre des techniques de reproduction et de traitement industriels de la couleur. Dans le cas de l'equivalence de couleur les etudes de la perception humaine ont joue un role important et ont permis d'etablir des normes par la cie. Mais l'apparence des couleurs dans des conditions quelconques d'observation reste non maitrisee. Dans cette etude, nous proposons des modeles de perception de la couleur bases sur la biologie de la retine. Ces modeles s'appliquent a l'echantillonnage de la couleur par les cones de la retine, aux non-linearites de traitement du signal chromatique et au traitement spatio-temporel du signal chromatique par les couches de neurones de la retine. Ces modeles permettent de comprendre le codage de la couleur en oppositions de couleur, la formation des seuils de discrimination couleur et les caracteristiques de filtrage spatial et temporel du signal de couleur au sein de la retine. Ces elements font de la retine un capteur efficace et robuste pour l'analyse des images naturelles. Les resultats de cette etude permettent d'envisager la realisation de circuits analogiques copiant les caracteristiques de traitement de la retine car nos modeles sont transposables en circuits electriques. Ils permettent egalement la definition d'une colorimetrie adaptative tenant compte des phenomenes d'adaptation dans les conditions de vision photopique. Enfin ils fournissent une methode d'analyse vectoriels des images, pour lesquel on dispose d'un vecteur de caracteristiques en chaque pixel.
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Neda, Milić. "Model optimizacije slike za korisnike sa poremećajima viđenja boja." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2016. http://www.cris.uns.ac.rs/record.jsf?recordId=99904&source=NDLTD&language=en.
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Predmet disertacije jeste optimizacija digitalne slike kadaograničenje nije vezano za način reprodukcije već za samog posmatrača,odnosno optimizacija opaženog kvaliteta digitalne slike od straneosoba sa poremećajima viđenja boja. Predloženi model optimizacijeslike poboljšava distinkciju boja i opseg boja slike za korisnike sarazličitim težinama poremećaja viđenja boja uz očuvanje prirodnostislike. Metodološki okvir ispitivanja, koji uključuje kvantitativnuanalizu računarskih simulacija, analizu eye-tracking podataka isubjektivno ocenjivanje poboljšanja opaženog kvaliteta test slika,daje sistematičnu i pouzdanu verifikaciju efektnosti predloženihmetoda adaptacije boja slike.The subject of the thesis was the digital image optimization when anobserver represents the main image reproduction limitation or, in otherwords, the optimization of the perceived image quality by individuals withcolour vision deficiencies. The proposed image optimization model enhancescolour distinction and gamut for users with different severities of colourblindnesswhile preserving the image naturalness. The used methodologicalframework, including a quantitative analysis of computer simulations, ananalysis of eye-tracking data and a subjective evaluation of the perceivedimage quality, provides systematic and reliable effectiveness verification ofthe proposed colour adaptation methods.
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Danelljan, Martin. "Visual Tracking." Thesis, Linköpings universitet, Datorseende, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-105659.
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Visual tracking is a classical computer vision problem with many important applications in areas such as robotics, surveillance and driver assistance. The task is to follow a target in an image sequence. The target can be any object of interest, for example a human, a car or a football. Humans perform accurate visual tracking with little effort, while it remains a difficult computer vision problem. It imposes major challenges, such as appearance changes, occlusions and background clutter. Visual tracking is thus an open research topic, but significant progress has been made in the last few years. The first part of this thesis explores generic tracking, where nothing is known about the target except for its initial location in the sequence. A specific family of generic trackers that exploit the FFT for faster tracking-by-detection is studied. Among these, the CSK tracker have recently shown obtain competitive performance at extraordinary low computational costs. Three contributions are made to this type of trackers. Firstly, a new method for learning the target appearance is proposed and shown to outperform the original method. Secondly, different color descriptors are investigated for the tracking purpose. Evaluations show that the best descriptor greatly improves the tracking performance. Thirdly, an adaptive dimensionality reduction technique is proposed, which adaptively chooses the most important feature combinations to use. This technique significantly reduces the computational cost of the tracking task. Extensive evaluations show that the proposed tracker outperform state-of-the-art methods in literature, while operating at several times higher frame rate. In the second part of this thesis, the proposed generic tracking method is applied to human tracking in surveillance applications. A causal framework is constructed, that automatically detects and tracks humans in the scene. The system fuses information from generic tracking and state-of-the-art object detection in a Bayesian filtering framework. In addition, the system incorporates the identification and tracking of specific human parts to achieve better robustness and performance. Tracking results are demonstrated on a real-world benchmark sequence.
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Sandberg, David. "Model-Based Video Coding Using a Colour and Depth Camera." Thesis, Linköpings universitet, Datorseende, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68737.
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In this master thesis, a model-based video coding algorithm has been developed that uses input from a colour and depth camera, such as the Microsoft Kinect. Using a model-based representation of a video has several advantages over the commonly used block-based approach, used by the H.264 standard. For example, videos can be rendered in 3D, be viewed from alternative views, and have objects inserted into them for augmented reality and user interaction. This master thesis demonstrates a very efficient way of encoding the geometry of a scene. The results of the proposed algorithm show that it can reach very low bitrates with comparable results to the H.264 standard.I detta examensarbete har en modellbaserad videokodningsalgoritm utvecklats som använder data från en djup- och färgkamera, exempelvis Microsoft Kinect. Det finns flera fördelar med en modellbaserad representation av en video över den mer vanligt förekommande blockbaserade varianten, vilket används av bland annat H.264. Några exempel är möjligheten att rendera videon i 3D samt från alternativa vyer, placera in objekt i videon samt möjlighet för användaren att interagera med scenen. Detta examensarbete påvisar en väldigt effektiv metod för komprimering av scengeometri. Resultaten av den presenterade algoritmen visar att möjligheten att uppnå väldigt låg bithastighet med jämförelsebara resultat med H.264-standarden.
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Wood, John. "Statistical Background Models with Shadow Detection for Video Based Tracking." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8667.
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A common problem when using background models to segment moving objects from video sequences is that objects cast shadow usually significantly differ from the background and therefore get detected as foreground. This causes several problems when extracting and labeling objects, such as object shape distortion and several objects merging together. The purpose of this thesis is to explore various possibilities to handle this problem.
Three methods for statistical background modeling are reviewed. All methods work on a per pixel basis, the first is based on approximating the median, the next on using Gaussian mixture models, and the last one is based on channel representation. It is concluded that all methods detect cast shadows as foreground.
A study of existing methods to handle cast shadows has been carried out in order to gain knowledge on the subject and get ideas. A common approach is to transform the RGB-color representation into a representation that separates color into intensity and chromatic components in order to determine whether or not newly sampled pixel-values are related to the background. The color spaces HSV, IHSL, CIELAB, YCbCr, and a color model proposed in the literature (Horprasert et al.) are discussed and compared for the purpose of shadow detection. It is concluded that Horprasert's color model is the most suitable for this purpose.
The thesis ends with a proposal of a method to combine background modeling using Gaussian mixture models with shadow detection using Horprasert's color model. It is concluded that, while not perfect, such a combination can be very helpful in segmenting objects and detecting their cast shadow.
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Svoboda, Jan. "Algoritmy přepočtů gamutů ve správě barev." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220594.
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The thesis deals with colors - their representation in digital devices and how to provide the best color preservation accross different devices. In the first part of the work, the knowledge of colors and human vision is briefly summarized. Then color models and color spaces are elaborated, mainly those device independent. Spectrum of colors viewable or printable on a device - the gamut - is different for every device and there's a need of precise reproduction or record of color. That's why the system of color management is described further and especially the gamut mapping approaches and algorithms are mentioned. In the second part of the work, the implementation of how two algorithms of color gamut mapping (HPMINDE, SCLIP) can be implemented in MATLAB is described. In the third and last part of the work, the results of implemented algorithms are presented and discussed. These results are compared to results of commonly used color gamut mapping technique (Adobe Photoshop).
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Gabriel, Petr. "Klasifikace objektů v obrazech." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217783.
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This master's thesis deal with problems of classification objects on the basis of atributes get from images. This thesis pertain to a branch of computer vision. Describe possible instruments of classification (e.g. neural networks, decision tree, etc.). Essential part is description objects by means of atributes. They are imputs to classifier. Practical part of this thesis deal with classification of object collection, which can be usually found at home (e.g. scissors, compact disc, sticky, etc.). Analyzed image is preprocessed , segmented by thresholding in HSV color map. Then defects caused by a segmentation are reconstructed by morfological operations. After are determined atribute values, which are imputs to classifier. Classifier has form of decision tree.
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Šimunský, Martin. "Vliv barevných modelů na chování konvolučních neuronových sítí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416630.
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Current knowledge about impact of colour models on performance of convolutional neural network is investigated in the first part of this thesis. The experiment based on obtained knowledge is conducted in the second part. Six colour models HSV, CIE 1931 XYZ, CIE 1976 L*a*b*, YIQ a YCbCr and deep convolutional neural network ResNet-101 are used. RGB colour model achieved the highest classification accuracy, whereas HSV color model has the lowest accuracy in this experiment.
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Grant, Robert. "Signal-linear representations of colour for computer vision." Thesis, University of Canterbury. Computer Science and Software Engineering, 2010. http://hdl.handle.net/10092/5685.
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Most cameras detect colour by using sensors that separate red, green and blue wavelengths of light which is similar to the human eye. As such most colour information available for computer vision is represented in this trichromatic colour model, Red Green Blue or RGB. However this colour model is inadequate for most applications as objects requiring analysis are subject to the reflective properties of light, causing RGB colour to change across object surfaces. Many colour models have been borrowed from other disciplines which transform the RGB colour space into dimensions which are decorrelated to the reflective properties of light.
Unfortunately signal noise is present in all acquired video, corrupting the image information. Fortunately most noise is statistically predictable, causing offsets from the true values following a Poisson distribution. When the standard deviation of a noise distribution is known, then noise can be stochastically predicted and accounted for.
However transformations inside cameras and transformations between colour models often deform the image information in ways that make the noise distributions non-uniform over the colour model. When computer vision applications need to account for non-uniform noise, wider tolerances are required overall. This results in a loss of useful information and a reduction in discriminative power.
This thesis has a focus on the linearity of signal noise distributions in colour representations which are decorrelated to the reflective properties of light. Existing colour models are described and each of their components examined with their strengths and weaknesses discussed.
The results show that the proposed Signal Linear RGB (SLRGB) colour model achieves a transformation of the RGB colour space with uniform noise distributions along all axes under changes to camera properties. This colour space maintains a signal noise with a standard deviation of one unit across the space under changes of the camera parameters: white balance, exposure and gain. Experiments demonstrated that this proposed SLRGB model consistently provided improvements to linearity over RGB when used as a basis for other colour models.
The proposed Minimum Weighted Colour Comparison (MWCC) method allows reflectively decorrelated colour models to make colour comparisons which counter the deforming effects of their coordinate systems. This was shown to provide substantial improvements to linearity tests in every case, making many colour models have a comparative noise linearity to undeformed colour models.
The proposed Planar Hue Luminance Saturation (PHLS) and Spherical Hue Luminance Saturation (SHLS) colour models are decorrelated to reflective properties of light and allow for signal linear colour comparisons. When used for pixel classification of coloured objects the PHLS and SHLS colour models used only 0.26% and 0.25% of the colour volume to classify all of the objects, with the next best using 0.88% without MWCC and 0.45% with.
The proposed Gamut Limit Invariant (GLI) colour model extends the decorrelation of reflective properties of light further by correcting for colours which are too bright and are clipped by the limits of the RGB space. When clipping occurs the properties become no longer decorrelated and shift. GLI models these changes to estimate the original values for clipped colours. The results show that this method improves decorrelation when performing pixel classification of coloured objects with varying proportions of clipped colours.
Overall, the results show that the proposed framework of colour models and methods are a significant improvement over all prior colour models in enabling the most accurate information possible for processing colour images.
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Huisman, Maximiliaan. "Vision Beyond Optics: Standardization, Evaluation and Innovation for Fluorescence Microscopy in Life Sciences." eScholarship@UMMS, 2019. https://escholarship.umassmed.edu/gsbs_diss/1017.
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Fluorescence microscopy is an essential tool in biomedical sciences that allows specific molecules to be visualized in the complex and crowded environment of cells. The continuous introduction of new imaging techniques makes microscopes more powerful and versatile, but there is more than meets the eye. In addition to develop- ing new methods, we can work towards getting the most out of existing data and technologies. By harnessing unused potential, this work aims to increase the richness, reliability, and power of fluorescence microscopy data in three key ways: through standardization, evaluation and innovation.
A universal standard makes it easier to assess, compare and analyze imaging data – from the level of a single laboratory to the broader life sciences community. We propose a data-standard for fluorescence microscopy that can increase the confidence in experimental results, facilitate the exchange of data, and maximize compatibility with current and future data analysis techniques.
Cutting-edge imaging technologies often rely on sophisticated hardware and multi-layered algorithms for reconstruction and analysis. Consequently, the trustworthiness of new methods can be difficult to assess. To evaluate the reliability and limitations of complex methods, quantitative analyses – such as the one present here for the 3D SPEED method – are paramount.
The limited resolution of optical microscopes prevents direct observation of macro- molecules like DNA and RNA. We present a multi-color, achromatic, cryogenic fluorescence microscope that has the potential to produce multi-color images with sub-nanometer precision. This innovation would move fluorescence imaging beyond the limitations of optics and into the world of molecular resolution.
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Havelka, Robert. "Detekce ohně a kouře ve videosekvenci." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2010. http://www.nusl.cz/ntk/nusl-235560.
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This master's thesis deals with fire detection in videosequences. Attention is paid to the known characteristics of fire and basic principles of existing solutions which deal with this issue. The thesis also describes design, implementation and testing of a fire detector that is based on the recognition of suspicious areas by fire color modeling, combined with detection of motion and light intensity variations.
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Hasnat, Md Abul. "Unsupervised 3D image clustering and extension to joint color and depth segmentation." Thesis, Saint-Etienne, 2014. http://www.theses.fr/2014STET4013/document.
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L'accès aux séquences d'images 3D s'est aujourd'hui démocratisé, grâce aux récentes avancées dans le développement des capteurs de profondeur ainsi que des méthodes permettant de manipuler des informations 3D à partir d'images 2D. De ce fait, il y a une attente importante de la part de la communauté scientifique de la vision par ordinateur dans l'intégration de l'information 3D. En effet, des travaux de recherche ont montré que les performances de certaines applications pouvaient être améliorées en intégrant l'information 3D. Cependant, il reste des problèmes à résoudre pour l'analyse et la segmentation de scènes intérieures comme (a) comment l'information 3D peut-elle être exploitée au mieux ? et (b) quelle est la meilleure manière de prendre en compte de manière conjointe les informations couleur et 3D ? Nous abordons ces deux questions dans cette thèse et nous proposons de nouvelles méthodes non supervisées pour la classification d'images 3D et la segmentation prenant en compte de manière conjointe les informations de couleur et de profondeur. A cet effet, nous formulons l'hypothèse que les normales aux surfaces dans les images 3D sont des éléments à prendre en compte pour leur analyse, et leurs distributions sont modélisables à l'aide de lois de mélange. Nous utilisons la méthode dite « Bregman Soft Clustering » afin d'être efficace d'un point de vue calculatoire. De plus, nous étudions plusieurs lois de probabilités permettant de modéliser les distributions de directions : la loi de von Mises-Fisher et la loi de Watson. Les méthodes de classification « basées modèles » proposées sont ensuite validées en utilisant des données de synthèse puis nous montrons leur intérêt pour l'analyse des images 3D (ou de profondeur). Une nouvelle méthode de segmentation d'images couleur et profondeur, appelées aussi images RGB-D, exploitant conjointement la couleur, la position 3D, et la normale locale est alors développée par extension des précédentes méthodes et en introduisant une méthode statistique de fusion de régions « planes » à l'aide d'un graphe. Les résultats montrent que la méthode proposée donne des résultats au moins comparables aux méthodes de l'état de l'art tout en demandant moins de temps de calcul. De plus, elle ouvre des perspectives nouvelles pour la fusion non supervisée des informations de couleur et de géométrie. Nous sommes convaincus que les méthodes proposées dans cette thèse pourront être utilisées pour la classification d'autres types de données comme la parole, les données d'expression en génétique, etc. Elles devraient aussi permettre la réalisation de tâches complexes comme l'analyse conjointe de données contenant des images et de la paroleAccess to the 3D images at a reasonable frame rate is widespread now, thanks to the recent advances in low cost depth sensors as well as the efficient methods to compute 3D from 2D images. As a consequence, it is highly demanding to enhance the capability of existing computer vision applications by incorporating 3D information. Indeed, it has been demonstrated in numerous researches that the accuracy of different tasks increases by including 3D information as an additional feature. However, for the task of indoor scene analysis and segmentation, it remains several important issues, such as: (a) how the 3D information itself can be exploited? and (b) what is the best way to fuse color and 3D in an unsupervised manner? In this thesis, we address these issues and propose novel unsupervised methods for 3D image clustering and joint color and depth image segmentation. To this aim, we consider image normals as the prominent feature from 3D image and cluster them with methods based on finite statistical mixture models. We consider Bregman Soft Clustering method to ensure computationally efficient clustering. Moreover, we exploit several probability distributions from directional statistics, such as the von Mises-Fisher distribution and the Watson distribution. By combining these, we propose novel Model Based Clustering methods. We empirically validate these methods using synthetic data and then demonstrate their application for 3D/depth image analysis. Afterward, we extend these methods to segment synchronized 3D and color image, also called RGB-D image. To this aim, first we propose a statistical image generation model for RGB-D image. Then, we propose novel RGB-D segmentation method using a joint color-spatial-axial clustering and a statistical planar region merging method. Results show that, the proposed method is comparable with the state of the art methods and requires less computation time. Moreover, it opens interesting perspectives to fuse color and geometry in an unsupervised manner. We believe that the methods proposed in this thesis are equally applicable and extendable for clustering different types of data, such as speech, gene expressions, etc. Moreover, they can be used for complex tasks, such as joint image-speech data analysis
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Gilbert, B. John. "Color Vision in the Bovine." DigitalCommons@USU, 1985. https://digitalcommons.usu.edu/etd/4117.
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Eight heifers were trained using operant conditioning to press a plate to receive a feed reward. Different wavelengths of light were presented as correct and incorrect stimuli. Positive and negative responses to the stimuli were registered electronically. Daily sessions of 17 minutes were conducted in a chamber with external light being excluded.
The duration of the stimulus was fixed at 17 seconds after which stimuli were randomly presented. Only presses on the plate when the correct stimulus was presented were reinforced with feed. A 75% correct choice was the criterion used as acceptable discrimination.
Ratios of correct to incorrect responses were computed. A stability of response was judged to occur when the median of these ratios over 5 days did not differ by more than .05 from the median of the ratios from the previous 5 sessions. Three colors i.e. green {535nm), red {610nm), and blue {450nm) were compared pairwise during 8 trials. Trial 7 was a repeat trial of green vs red and trial 8 was a comparison of green vs green.
Heifers gave random response to green vs green. Red was distinguished from blue by five of the heifers: 1, 2, 3, 4, and 5 at 76%, 91%, 78%, 88%, and 81% correct choice respectively. Blue was distinguished from green by three of the heifers: 1, 2, and 5 at 89%, 88%, and 85% correct choice respectively. Green was distinguished from red by three of the heifers: 1, 5, and 7 at 90%, 84%, and 85% correct choice respectively. These last discriminations we r e made in the repeat trial of green vs red after heifers failed to do so in the first trial of green vs red. Color discrimination and discrimination learning have been demonstrated by these results.
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Voraphani, Natthapongs. "Color vision screening using eye movements." [Ames, Iowa : Iowa State University], 2007.
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Srinivasan, Ramprakash. "Computational Models of the Production and Perception of Facial Expressions." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531239299392184.
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Stokman, Harro. "Robust photometric invariance in machine color vision." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/56969.
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Wright, Anne R. (Anne Renée). "A low-cost color vision tracking system." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10896.
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Neuschwanger, Christina Mary. "The development of color and motion processing /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2003. http://wwwlib.umi.com/cr/ucsd/fullcit?p3096419.
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Ivins, James P. "Statistical snakes: active region models." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484310.
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Kwok, Pui-yan Veronica, and 郭沛殷. "Learning new color names produces lateralized categorical color perception: a training study." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B49858592.
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Previous behavioral and neuroimaging findings (Drivonikou, et al., 2007; Gilbert, et al., 2006; Tan, et al., 2008; Siok, et al., 2009) indicate that reaction times to targets in visual search are faster in the right than the left visual field when the target and distractor colors straddle a category boundary. This phenomenon is known as the lateralized categorical color perception, which supports the weaker form of Whorf’s hypothesis that linguistic information shapes color perception. Yet, these studies did not demonstrate a definite cause and effect relation between language and perception. The observed lateralized category effect of color perception may either rely on the individual’s innate color categories or his linguistic experience.
In the present study, we used an intensive training method to study categorical perception (CP) of color. We aimed to show a definite causal relation between language and perception. In Experiment 1, 37 native Mandarin speakers were tested with a color discrimination task. We taught 20 participants four new linguistic items for the four stimulus colors which were initially from the same lexical category (two blues and two greens) whilst other participants did not learn any new color names. Performances between the two groups were compared before and after training. Experiment 2 was based on Zhou et al.’s (2010) behavioral study, in which we used the same training procedure and measured and contrasted 19 participants’ brain structure before and after training.
In experiment 1, participants exhibited lateralized Whorf effect when performing the visual search task at the pre-training phase. After training, the experimental group successfully acquired the new color names, reflected by overall shorter reaction time and higher task accuracy, while the control group did not show significant difference in the performance across two phases. The improved performance of experimental group implicated that the newly learned categories altered participants’ color perception pattern. However, we failed to show lateralized Whorf effect at the post-training phase due to several experimental flaws. In Experiment 2, gray matter density is found to increase in color region of the left visual cortex after a short-term training (less than two hours). The data provided strong structural evidence for newly-learned categorical color perception and also suggested structural plasticity of the human brain. The results from this study indicate that language experience shapes perception, both functionally and structurally, after a period of learning that is much shorter than previously established (Draganski, 2004; Carreiras, et al., 2009; Trachtenberg, 2002).published_or_final_version
Linguistics
Master
Master of Philosophy
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Redfield, Signe Anne. "Efficient object recognition using color quantization." [Gainesville, Fla.] : University of Florida, 2001. http://purl.fcla.edu/fcla/etd/UFE0000347.
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Thesis (Ph. D.)--University of Florida, 2001.Title from title page of source document. Document formatted into pages; contains xiv, 150 p.; also contains graphics. Includes vita. Includes bibliographical references.
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Бабкова, Надія Вікторівна. "Моделі та інформаційна технологія ідентифікації фізичних параметрів високотемпературних процесів." Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/28147.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.13.06 – інформаційні технології. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Мета дисертаційного дослідження – підвищення ефективності процесу визначення теплофізичних параметрів на основі розробки моделей і методів цифрової обробки зображень та інформаційної технології ідентифікації фізичних параметрів температурних процесів. Основні результати: уперше запропоновано розв'язання зворотної задачі конвективного теплообміну на основі використання інструментів алгебри скінченних предикатів і теорії цифрової обробки зображень, що дозволяє визначити характеристики об'єкта, який випромінює, за його цифровим зображенням; отримав подальший розвиток метод визначення температурних полів за цифровим зображенням процесу, що дозволяє вирішити задачу визначення фізичних параметрів оребрених структур; удосконалено метод визначення теплофізичних параметрів і побудови температурних полів теплового процесу на основі тривимірної моделі кольорового зору людини та розробленої дискретної моделі передачі тепла в оребрених трубах, що дозволяє визначити оптимальні значення параметрів оребрення в процесі передачі тепла від нагрітих газів у робоче середовище; удосконалено інформаційну технологію визначення фізичних параметрів і побудови температурних полів теплового процесу, яка дозволяє автоматизувати процес обробки теплотехнічної інформації та вдосконалити процес моніторингу стану об'єкта за рахунок визначення зон накладення температурних полів.Thesis for a candidate degree in technical science, specialty 05.13.06 – Information Technologies. – National Technical University "Kharkiv Polytechnic Institute". – Kharkiv, 2017. The aim of the research lies in the improvement of the effectiveness of the determination process of thermal parameters based on the development models and methods of digital imaging and information technologies identification of the physical parameters of temperature processes. The main results: for the first time it is offered the solution to the inverse problem of convective heat transfer based on the us-age of algebra and theory of finite predicates tools and the theory of digital imaging that allows to determine the characteristics of the object that emits according to its digital image; the method of determining the temperature fields according to the digital image process got its further development and that helps to solve the problem of physical parameters ribbed structures; it was also improved the method of deter-mining the thermal parameters and temperature fields of building thermal process based on three-dimensional model of human color vision and developed discrete model of heat transfer in ribbed tubes that enabled to determine the optimal values of ribs in the process of heat transfer from hot gases into the working environment; it was improved the information technology of determining the physical parameters and temperature fields of building thermal process that automates the process of heating the processing of information and improve the process of monitoring the state of the object on the account of the determination of the imposition temperature fields areas.
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Azeff, Liza. "The role of color vision in shape discrimination /." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97897.
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The purpose of this project is to study the role of human color vision in shape processing. We examine the extent to which color vision can contribute to complex shape processing tasks or whether they are accomplished mainly by the achromatic pathways of the brain. We tested normal human visual performance using psychophysical experiments. The stimuli were presented on a monitor and the task of the subject is to indicate whether shape differences in the stimuli have been seen. Each psychophysical trial was run four-to-five times using a two-interval forced choice paradigm. Stimuli were calibrated so that they selectively activate either the achromatic pathways (black & white) pathways or the color (red-green and blue-yellow) pathways of the human brain. The results of the study show that color vision can perform many of the various types of shape discrimination tasks at similar levels to achromatic vision.
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Cerda-Company, Xim. "Understanding color vision: from psychophysics to computational modeling." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667177.
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En aquest doctorat, hem estudiat la visió del color dels humans des de dos punts de vista diferents: la psicofísica i la modelització computacional. Primer, hem avaluat 15 "tone-mapping operators" (TMOs) diferents en dos experiments que consideren criteris diferents: el primer té en compte les relacions locals entre nivells d'intensitat i el segon avalua l'aparença global de la imatge resultant respecte l'escena física (presentades una al costat de l'altra). La conclusió és que els rankings depenen del criteri utilitzat i que no estan correlacionats. Considerant els dos criteris, els millors TMOs són el KimKautz (Kim and Kautz, 2008) i el Krawczyk (Krawczyk et al., 2005). Tot i això, s'han de definir criteris estàndards per a poder fer una comparació justa entre els diferents TMOs.
Després, hem realitzat diferents experiments psicofísics per estudiar la inducció del color. Bàsicament, hem estudiat dues propietats diferents dels estímuls: la freqüència temporal i la distribució espaial de la lluminància. Per a estudiar la freqüència temporal, vam definir uns estímuls equiluminants compostos per voltants uniformes i ratllats, els quals els vam mostrar durant un flash. En els voltants uniformes, els resultats mostren que la inducció del color depèn de la duració del flash i de la cromaticitat del inductor. Tal com esperàvem, en totes les diferents condicions cromàtiques, es va induir contrast cromàtic. Per contra, en els voltants ratllats, esperàvem induir assimilació cromàtica, però vam observar contrast o no inducció. Com que estímuls ratllats similars, que no són equiluminants, indueixen assimilació del color, vam concloure que les diferències llumíniques podien ser un factor clau per a la inducció. Per tant, hem analitzat l'efecte de les diferències llumíniques en l'assimilació. Vam variar les diferències de lluminància entre la regió d'interès i els seus inductors i vam veure que l'assimilació cromàtica depèn d'aquestes diferències i de la cromaticitat del inductor. En la condició vermell-verd (quan el primer inductor és vermell i el segon és verd), l'assimilació de color es produeix en gairebé totes les condicions llumíniques. En canvi, en el cas del verd-vermell, mai s'observa assimilació del color. Les condicions lila-llima i llima-lila mostren clarament que la diferència llumínica és un factor clau per induir assimilació del color. Quan la regió d'interès és més fosca que el seu voltant, l'efecte és més fort en la condició lila-llima, mentre que quan la regió d'interès és més brillant, l'efecte és més fort en la condició llima-lila (efecte mirall). A més a més, vam avaluar si l'assimilació del color ve donada per diferències llumíniques o de brillantor. De manera similar a la condició equiluminant, no s'observa assimilació del color quan l'estímul és equibrillant. Els nostres resultats donen suport a la hipòtesis que la inhibició mútua juga un rol important en la percepció del color, o com a mínim en la inducció del color.
Finalment, hem definit un nou model del processament del color (del "parvocellular pathway") a V1. Hem modelitzat dues capes diferents: les capes 4Cβ i 2/3. El nostre model és una xarxa dinàmica recurrent que considera neurones excitadores i inhibidores i les seves connexions laterals. A més, també considera les diferències laminars existents i les diferents cèl·lules que les componen. Per tant, hem modelitzat les neurones simples "single-" i "double-opponent" i les neurones complexes, les quals es consideren un conjunt de neurones simples "double-opponent". Per testejar l'arquitectura, hem utilitzat un conjunt the "drifting gratings" sinusoïdals i hem variat algunes de les seves propietats com la freqüència temporal i espaial, la seva àrea i la seva orientació. Per repoduir les observacions electrofisiològiques, vam haver de suposar l'existència d'unes neurones "double-opponent" sense selectivitat a orientació i la falta de connexions laterals entre neurones "single-opponent". A més a més, hem testejat les connexions laterals modelitzades simulant la modulació del centre i voltant. Hem observat que quan l'estímul té un alt contrast, el resultat d'aquestes connexions és inhibitori, però és facilitatori quan el contrast és baix.In this PhD we have approached the human color vision from two different points of view: psychophysics and computational modeling. First, we have evaluated 15 different tone-mapping operators (TMOs). We have conducted two experiments that consider two different criteria: the first one evaluates the local relationships among intensity levels and the second one evaluates the global appearance of the tone-mapped images w.r.t. the physical one (presented side by side). We conclude that the rankings depend on the criterion and they are not correlated. Considering both criteria, the best TMOs are KimKautz (Kim and Kautz, 2008) and Krawczyk (Krawczyk et al., 2005). Another conclusion is that a more standardized evaluation criteria is needed to do a fair comparison among TMOs. Secondly, we have conducted several psychophysical experiments to study the color induction. We have studied two different properties of the visual stimuli: temporal frequency and luminance spatial distribution. To study the temporal frequency we defined equiluminant stimuli composed by both uniform and striped surrounds and we flashed them varying the flash duration. For uniform surrounds, the results show that color induction depends on both the flash duration and inducer's chromaticity. As expected, in all chromatic conditions color contrast was induced. In contrast, for striped surrounds, we expected to induce color assimilation, but we observed color contrast or no induction. Since similar but not equiluminant striped stimuli induce color assimilation, we concluded that luminance differences could be a key factor to induce color assimilation. Thus, in a subsequent study, we have studied the luminance differences' effect on color assimilation. We varied the luminance difference between the target region and its inducers and we observed that color assimilation depends on both this difference and the inducer's chromaticity. For red-green condition (where the first inducer is red and the second one is green), color assimilation occurs in almost all luminance conditions. Instead, for green-red condition, color assimilation never occurs. Purple-lime and lime-purple chromatic conditions show that luminance difference is a key factor to induce color assimilation. When the target is darker than its surround, color assimilation is stronger in purple-lime, while when the target is brighter, color assimilation is stronger in lime-purple ('mirroring' effect). Moreover, we evaluated whether color assimilation is due to luminance or brightness differences. Similarly to equiluminance condition, when the stimuli are equibrightness no color assimilation is induced. Our results support the hypothesis that mutual-inhibition plays a major role in color perception, or at least in color induction. Finally, we have defined a new firing rate model of color processing in the V1 parvocellular pathway. We have modeled two different layers of this cortical area: layers 4Cβ and 2/3. Our model is a recurrent dynamic computational model that considers both excitatory and inhibitory cells and their lateral connections. Moreover, it considers the existent laminar differences and the cells' variety. Thus, we have modeled both single- and double-opponent simple cells and complex cells, which are a pool of double-opponent simple cells. A set of sinusoidal drifting gratings have been used to test the architecture. In these gratings we have varied several spatial properties such as temporal and spatial frequencies, grating's area and orientation. To reproduce the electrophysiological observations, the architecture has to consider the existence of non-oriented double-opponent cells in layer 4Cβ and the lack of lateral connections between single-opponent cells. Moreover, we have tested our lateral connections simulating the center-surround modulation and we have reproduced physiological measurements where for high contrast stimulus, the result of the lateral connections is inhibitory, while it is facilitatory for low contrast stimulus.
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Seemiller, Eric S. "Selective pressures influencing color-vision in Neotropical primates." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1309883439.
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Martinez, Elizabeth. "Bisection of cognitive color space : do individual "midpoint" judgements reveal the dimensional structure of suprathreshold color differences /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2003. http://wwwlib.umi.com/cr/ucsd/fullcit?p3112197.
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Szmajda, Brett A. "Subcortical pathways for colour vision /." Connect to thesis, 2006. http://eprints.unimelb.edu.au/archive/00003165.
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Thesis (Ph.D.)--University of Melbourne, The National Vision Research Institute of Australia and Dept. of Optometry & Vision Sciences, 2007.Typescript. Includes bibliographical references (leaves 95-111).
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Harouna, Seybou Aboubacar. "Analyse d'images couleurs pour le contrôle qualité non destructif." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2282/document.
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La couleur est un critère important dans de nombreux secteurs d'activité pour identifier, comparer ou encore contrôler la qualité de produits. Cette tâche est souvent assumée par un opérateur humain qui effectue un contrôle visuel. Malheureusement la subjectivité de celui-ci rend ces contrôles peu fiables ou répétables. Pour contourner ces limitations, l'utilisation d'une caméra RGB permet d'acquérir et d'extraire des propriétés photométriques. Cette solution est facile à mettre en place et offre une rapidité de contrôle. Cependant, elle est sensible au phénomène de métamérisme. La mesure de réflectance spectrale est alors la solution la plus appropriée pour s'assurer de la conformité colorimétrique entre des échantillons et une référence. Ainsi dans l'imprimerie, des spectrophotomètres sont utilisés pour mesurer des patchs uniformes imprimés sur une bande latérale. Pour contrôler l'ensemble d'une surface imprimée, des caméras multi-spectrales sont utilisées pour estimer la réflectance de chaque pixel. Cependant, elles sont couteuses comparées aux caméras conventionnelles. Dans ces travaux de recherche, nous étudions l'utilisation d'une caméra RGB pour l'estimation de la réflectance dans le cadre de l'imprimerie. Nous proposons une description spectrale complète de la chaîne de reproduction pour réduire le nombre de mesures dans les phases d'apprentissage et pour compenser les limitations de l'acquisition. Notre première contribution concerne la prise en compte des limitations colorimétriques lors de la caractérisation spectrale d'une caméra. La deuxième contribution est l'exploitation du modèle spectrale de l'imprimante dans les méthodes d'estimation de réflectanceColor is a major criterion for many sectors to identify, to compare or simply to control the quality of products. This task is generally assumed by a human operator who performs a visual inspection. Unfortunately, this method is unreliable and not repeatable due to the subjectivity of the operator. To avoid these limitations, a RGB camera can be used to capture and extract the photometric properties. This method is simple to deploy and permits a high speed control. However, it's very sensitive to the metamerism effects. Therefore, the reflectance measurement is the more reliable solution to ensure the conformity between samples and a reference. Thus in printing industry, spectrophotometers are used to measure uniform color patches printed on a lateral band. For a control of the entire printed surface, multispectral cameras are used to estimate the reflectance of each pixel. However, they are very expensive compared to conventional cameras. In this thesis, we study the use of an RGB camera for the spectral reflectance estimation in the context of printing. We propose a complete spectral description of the reproduction chain to reduce the number of measurements in the training stages and to compensate for the acquisition limitations. Our first main contribution concerns the consideration of the colorimetric limitations in the spectral characterization of a camera. The second main contribution is the exploitation of the spectral printer model in the reflectance estimation methods
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Бабкова, Надія Вікторівна. "Моделі та інформаційна технологія ідентифікації фізичних параметрів високотемпературних процесів." Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/28146.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.13.06 – інформаційні технології. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Мета дисертаційного дослідження – підвищення ефективності процесу визначення теплофізичних параметрів на основі розробки моделей і методів цифрової обробки зображень та інформаційної технології ідентифікації фізичних параметрів температурних процесів. Основні результати: уперше запропоновано розв'язання зворотної задачі конвективного теплообміну на основі використання інструментів алгебри скінченних предикатів і теорії цифрової обробки зображень, що дозволяє визначити характеристики об'єкта, який випромінює, за його цифровим зображенням; отримав подальший розвиток метод визначення температурних полів за цифровим зображенням процесу, що дозволяє вирішити задачу визначення фізичних параметрів оребрених структур; удосконалено метод визначення теплофізичних параметрів і побудови температурних полів теплового процесу на основі тривимірної моделі кольорового зору людини та розробленої дискретної моделі передачі тепла в оребрених трубах, що дозволяє визначити оптимальні значення параметрів оребрення в процесі передачі тепла від нагрітих газів у робоче середовище; удосконалено інформаційну технологію визначення фізичних параметрів і побудови температурних полів теплового процесу, яка дозволяє автоматизувати процес обробки теплотехнічної інформації та вдосконалити процес моніторингу стану об'єкта за рахунок визначення зон накладення температурних полів.Thesis for a candidate degree in technical science, specialty 05.13.06 – Information Technologies. – National Technical University "Kharkiv Polytechnic Institute". – Kharkiv, 2017. The aim of the research lies in the improvement of the effectiveness of the determination process of thermal parameters based on the development models and methods of digital imaging and information technologies identification of the physical parameters of temperature processes. The main results: for the first time it is offered the solution to the inverse problem of convective heat transfer based on the us-age of algebra and theory of finite predicates tools and the theory of digital imaging that allows to determine the characteristics of the object that emits according to its digital image; the method of determining the temperature fields according to the digital image process got its further development and that helps to solve the problem of physical parameters ribbed structures; it was also improved the method of deter-mining the thermal parameters and temperature fields of building thermal process based on three-dimensional model of human color vision and developed discrete model of heat transfer in ribbed tubes that enabled to determine the optimal values of ribs in the process of heat transfer from hot gases into the working environment; it was improved the information technology of determining the physical parameters and temperature fields of building thermal process that automates the process of heating the processing of information and improve the process of monitoring the state of the object on the account of the determination of the imposition temperature fields areas.
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Eisen, Paul S. "An evaluation of the manipulation of color in alternative color spaces." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43852.
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The amenability of various color-controlling algorithms to the real-time operator control of color stimuli was investigated. Mathematical models based on eight color spaces were employed: three uniform color spaces (L*u*v*, L*h*C*, and Y 2.2u' VI), a graphics algorithm (HLS), an opponent color model, the NTSC broadcast signals (YIQ), and two sets of color primaries. Eighty subjects, divided equally among the color spaces, were required to match colors under time-limited conditions.
The apparatus employed was a color-manipulation device using LEDs, custom-built in the Displays and Controls Laboratory at Virginia Tech. The device allows for 12-bit resolution on each color channel and higher stability of luminance and chrominance over the short and long term than can be achieved with experimental quality CRTs.Master of Science
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Gunther, Karen La Vaughn. "The neural mechanisms underlying color perception /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3044771.
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