The process of color-matching any color product is a process that can be quite complicated and requires great skill from a color analyst. As the name suggests color-matching is the process in which the color of a standard is obtained from a sample through careful inspection and precision in order for the colors to match up. It is a process that can vary in length dependent of the amount of pigments used.  Foundations are a type of liquid emulsion cosmetic and consist of five main pigments; white (titanium dioxide), red, brown, yellow and black iron oxides. These five pigments can when mixed together result in hundreds of shades. One of the greatest challenges for cosmetics companies is to successfully manufacture these shades often from a benchmark, a desired shade, as well as maintaining this same shade when the batch is scaled up from lab production to factory.  Oriflame is a direct-selling cosmetics company in which the Marketing department and Color Cosmetic department work closely in order to produce new products and shades for each catalogue. Liquid foundation shades are decided by the Marketing department and given to the Color Cosmetic department to color-match.  Currently the process of color-matching is carried out through the visual assessment by the color analyst. In order to improve the efficiency and lead - time of the current method, Oriflame has drawn inspiration from other sectors dealing with color and taken the decision to color-match with the use of a spectrophotometer coupled with color-appropriate software. The method was divided into four separate processes; confirming a sample method presentation to the spectrophotometer, colorant file set-up & process, color-matching process with the color-appropriate software and color match comparison. The results showed that with an adequate sized colorant file a method for color-matching with a spectrophotometer was established. The lead-time could be decreased by, as much as 66.6 % and providing strong evidence that this is a valuable tool for color analysts working at Oriflame.

This thesis describes the development of a commercial machine vision system as a case study for utilizing the Modular Reprogrammable Real-time Processing Hardware (MORRPH) board. The commercial system described in this thesis is based on a prototype system that was developed as a test-bed for developing the necessary concepts and algorithms. The prototype system utilized color linescan cameras, custom framegrabbers, and standard PCs to color-sort red oak parts (staves). When a furniture manufacturer is building a panel, very often they come from edge-glued paneled parts. These are panels formed by gluing several smaller staves together along their edges to form a larger panel. The value of the panel is very much dependent upon the "match" of the individual staves—i.e. how well they create the illusion that the panel came from a single board as opposed to several staves. The prototype system was able to accurately classify staves based on color into classes defined through a training process. Based on Trichromatic Color Theory, the system developed a probability density function in 3-D color space for each class based on the parts assigned to that class during training. While sorting, the probability density function was generated for each scanned piece, and compared with each of the class probability density functions. The piece was labeled the name of the class whose probability density function it most closely matched. A "best-face" algorithm was also developed to arbitrate between pieces whose top and bottom faces did not fall into the same classes. [1] describes the prototype system in much greater detail. In developing a commercial-quality machine vision system based on the prototype, the primary goal was to improve throughput. A Field Programmable Gate Array (FPGA)-based Custom Computing Machine (FCCM) called the MORRPH was selected to assume most of the computational burden, and increase throughput in the commercial system. The MORRPH was implemented as an ISA-bus interface card, with a 3 x 2 array of Processing Elements (PE). Each PE consists of an open socket which can be populated with a Xilinx 4000 series FPGA, and an open support socket which can be populated with support chips such as external RAM, math processors, etc. In implementing the prototype algorithms for the commercial system, a partition was created between those algorithms that would be implemented on the MORRPH board, and those that would be left as implemented on the host PC. It was decided to implement such algorithms as Field-Of-View operators, Shade Correction, Background Extraction, Gray-Scale Channel Generation, and Histogram Generation on the MORRPH board, and to leave the remainder of the classification algorithms on the host. By utilizing the MORRPH board, an industrial machine vision system was developed that has exceeded customer expectations for both accuracy and throughput. Additionally, the color-sorter received the International Woodworking Fair's Challengers Award for outstanding innovation. / Master of Science

La cryptographie visuelle consiste à partager entre plusieurs « Shadow Images » (SIs) un secret qui ne se révèlera à l'oeil de l'observateur qu'à leur superposition. Depuis les travaux de Naor et Shamir, ce procédé cryptographique a été étendu à Des schémas numériques variés, adaptés à diverses problématiques. En revanche, les travaux concernant son implémentation physique sont peu nombreux à ce jour. Cette thèse est consacrée à l'implémentation de la cryptographie visuelle sur des SIs imprimés en demi-tons en vue de l'authentification de documents. Le SI associé au document peut être imprimé sur support opaque ou transparent, les autres SIs étant imprimés sur films transparents. Nous avons résolu la difficulté de leur superposition par une méthode de Fourier permettant le recalage de la structure quasi-périodique d'un SI. La précision de cette méthode nous a permis de développer un système optique de superposition par projection. On verra que les phénomènes physiques responsables du rendu visuel de SIs superposés sont propices à une protection contre la copie illicite du SI associé à un document. La complexité de ces phénomènes et leur dépendance au type d'impression imposent une modélisation physique pour obtenir un rendu précis. Cette approche nous a conduit à considérer la problématique de la reproduction des couleurs et à développer des modèles spectraux adaptés à la superposition de supports imprimés non diffusants et/ou diffusants, en réflexion et en transmission. La précision de ces modèles prédictifs est tout à fait satisfaisante au regard de celle habituellement obtenue dans le domaine de la reproduction des couleurs. Cela nous a permis d'introduire une approche originale de la cryptographie visuelle par ajustement de couleur (color matching) : une même couleur, à une tolérance près basée sur la vision humaine, est générée par différents demi-tons imprimés sur les supports à superposer. La couleur du message peut ainsi constituer un secret partagé entre les SIs de la même façon que l'est le contenu du message. Chaque SI pris individuellement ne laisse fuir aucune information sur la couleur du message, qui ne sera révélée qu'à leur superposition. Cela peut permettre de prévenir une attaque par falsification du SI associé au document (cheating attack ). De plus, le rendu des couleurs étant très dépendant du système d'impression utilisé, une reproduction fidèle à partir d'un système d'impression différent est difficile. La difficulté peut être encore accrue par l'utilisation de caractéristiques d'impression non standard / In this thesis, we will focus on the physical implementation of visual cryptography, which consists in sharing a secret message between several unmeaning images, so-called shadow images, at least one of them being printed. By the principle of the method, no information leaks about the message until the images are properly stacked together. As the alignment of the shadow images hampers the deployment of the visual cryptography in practice, we develop a dedicated image registration method. In contrast with existing methods, ours is not intrusive. We make use of the particular shape of the elementary constituents of the shadow images, the shares, to extract in the Fourier domain the main parameters of the geometrical transformations occurring between the superposed images. We prove that this method allows subpixel accuracy in shadow images registration. We benefit from such ability by implementing visual cryptography in an image projection configuration : the digital shadow image is projected onto the printed one. In this way, the registration is performed automatically by using a digital camera (the resulting superposition being observable by the eye). For the purpose of authentication, one has to deal with specific attacks: the shadow image attached to a given document could be tampered with or copied. In order to prevent such attacks, we have increased the di_culty to reproduce the shadow image by considering color. This approach requires a complete management of colors. Thanks to recent advances in color reproduction, we are able to predict the reflectance and transmittance spectra of supports printed in color. In this thesis, we develop new spectral prediction models namely for piles of printed transparencies as well as for transparencies stacked onto papers, all printed in color. Thus, we are able to predict the color of each share in a shadow image to be printed and to achieve color matching i.e. we are able to reach a color by various combinations of superposed colors. Such a prediction allowed us to introduce a new approach in visual cryptography: color matching when revealing the secret message to be shared into two (or more) shadow images, in order to authenticate the shadow images provider. As the prediction models are sensitive to the calibration of the printing system (printer, inks, supports, halftoning and geometry measurement conditions), the use of special materials will increase the di_culty to generate visually acceptable fake pairs of shadow images

L'objectif de cette thèse est de proposer une solution au problème de la constance des couleurs entre les images d'une même scène acquises selon un même point de vue ou selon différents points de vue. Ce problème constitue un défi majeur en vision par ordinateur car d'un point de vue à l'autre, on peut être confronté à des variations des conditions d'éclairage (spectre de l'éclairage, intensité de l'éclairage) et des conditions de prise de vue (point de vue, type de caméra, paramètres d'acquisition tels que focus, exposition, balance des blancs, etc.). Ces variations induisent alors des différences d'apparence couleur entre les images acquises qui touchent soit sur l'ensemble de la scène observée soit sur une partie de celle-ci. Dans cette thèse, nous proposons une solution à ce problème qui permet de modéliser puis de compenser, de corriger, ces variations de couleur à partir d'une méthode basée sur quatre étapes : (1) calcul des correspondances géométriques à partir de points d'intérêt (SIFT et MESR) ; (2) calculs des correspondances couleurs à partir d'une approche locale; (3) modélisation de ces correspondances par une méthode de type RANSAC; (4) compensation des différences de couleur par une méthode polynomiale à partir de chacun des canaux couleur, puis par une méthode d'approximation linéaire conjuguée à une méthode d'estimation de l'illuminant de type CAT afin de tenir compte des intercorrélations entre canaux couleur et des changements couleur dus à l'illuminant. Cette solution est comparée aux autres approches de l'état de l'art. Afin d'évaluer quantitativement et qualitativement la pertinence, la performance et la robustesse de cette solution, nous proposons deux jeux d'images spécialement conçus à cet effet. Les résultats de différentes expérimentations que nous avons menées prouvent que la solution que nous proposons est plus performante que toutes les autres solutions proposées jusqu'alors / The objective of this thesis is to propose a solution to the problem of color consistency between images originate from the same scene irrespective of acquisition conditions. Therefore, we present a new color mapping framework that is able to compensate color differences and achieve color consistency between views of the same scene. Our proposed, new framework works in two phases. In the first phase, we propose a new method that can robustly collect color correspondences from the neighborhood of sparse feature correspondences, despite the low accuracy of feature correspondences. In the second phase, from these color correspondences, we introduce a new, two-step, robust estimation of the color mapping model: first, nonlinear channel-wise estimation; second, linear cross-channel estimation. For experimental assessment, we propose two new image datasets: one with ground truth for quantitative assessment; another, without the ground truth for qualitative assessment. We have demonstrated a series of experiments in order to investigate the robustness of our proposed framework as well as its comparison with the state of the art. We have also provided brief overview, sample results, and future perspectives of various applications of color mapping. In experimental results, we have demonstrated that, unlike many methods of the state of the art, our proposed color mapping is robust to changes of: illumination spectrum, illumination intensity, imaging devices (sensor, optic), imaging device settings (exposure, white balance), viewing conditions (viewing angle, viewing distance)

Improving color matching skills requires a specifically designed interface as much as well-calculated feedback on the underlying color model. This thesis relates to the production of a game for learning HSL and elaborates on learning patterns with regard to hue and game progression. A quantification of learning based on performance variation is proposed. In an effort to balance data quantity and relevance, several variables of pure analysis interest are defined. Results on learning inhomogeneities are presented through Hue Learning Curves with streamgraphs and detailed bar charts. The consequences of design choices and gameplay on performance and learning are discussed.

La protection des documents fiduciaires et identitaires contre la fraude exige le développement d’outils de contrôle fondés sur des effets visuels sans cesse renouvelés, difficiles à contrefaire (même pour un expert ... de la contrefaçon !). Ce projet de recherche s’inscrit dans cette problématique et vise à apporter des solutions originales via l’impression de supports diffusants d’une part, et le développement de modèles de rendu visuel d’autre part. Les effets visuels recherchés sont des ajustements de couleurs entre les deux faces d’un imprimé lorsque celui-ci est observé par transparence devant une source lumineuse. Pour obtenir facilement des ajustements de couleurs quelles que soient les couleurs visées, il est capital d’avoir un modèle à disposition, permettant de calculer les quantités d’encre à déposer. Un modèle doit être capable de prédire les facteurs spectraux de réflexion et de transmission du support imprimé en décrivant les phénomènes de diffusion optique présents en pratique dans les couches d’encre et le support. Nous nous intéressons plus particulièrement aux imprimés translucides contenant des couleurs en demi-ton des deux côtés de la surface avec pour objectif de prédire le rendu visuel pour diverses configurations d’observation. Pour cela, nous proposons une nouvelle approche basée sur l’utilisation de matrices de transfert de flux pour prédire les facteurs spectraux de réflexion et de transmission des imprimés lorsqu’ils sont éclairés simultanément des deux côtés. En représentant le comportement optique des différents composants d’un imprimé par des matrices de transfert, la description des transferts de flux entre ces composantes s’en trouve simplifiée. Ce cadre mathématique mène à la construction de modèles de prédiction de couleurs imprimées en demi-ton sur des supports diffusants. Nous montrons par ailleurs que certains modèles existants, comme le modèle de Kubelka-Munk ou encore le modèle de Clapper-Yule, peuvent également être formulés en termes de matrices de transfert. Les résultats obtenus avec les modèles proposés dans ce travail mettent en évidence des qualités de prédiction équivalentes, voire supérieures, à celles qu’on retrouve dans l’état de l’art, tout en proposant une simplification de la formulation mathématique et de la description physique des échanges de flux. Cette simplification fait de ces modèles des outils de calcul qui s’utilisent très facilement, notamment pour la détermination des quantités d’encre à déposer sur les deux faces de l’imprimé afin d’obtenir des ajustements de couleurs / The protection of banknotes or identity documents against counterfeiting demands the development of control tools based on visual effects that are continuously renewed. These visual effects become thus difficult to counterfeit even by an expert forger ! This research tries to deal with that issue. Its objective is to bring new solutions using on the one side, the printing of diffusing materials, and on the other side the development of visual rendering models that can be observed. The visual effects that are sought-after are the color matching on both sides of a printed document when observed against thelight. To easily obtain a color matching, whatever the colors that are aimed for, it is essential to have a model that helps in calculating the quantity of ink to be left on the document. A model must be used to predict the spectral reflectance and the transmittance factors of the printed document by describing the phenomena of optical diffusion really present in the ink layers and in the document. We shall focus our interest especially on translucent printed documents that have halftone colors on both sides. Our goal here is to predict the visual rendering in different configurations of observation. To that end, we are offering a new approach based on the use of flux transfer matrices to predict the spectral reflectance and transmittance factors of prints when they are simultaneously lit up on both sides. By representing with transfer matrices the optical behavior of the different components present in a printed document, we see that the description of flux transfer between these elements is thus simplified. This mathematical framework leads to the construction of prediction models of halftone printed colors on diffusing materials. We also show that some existing models, such as the Kubelka-Munk or the Clapper-Yule models, can also be formulated in transfer matrices terms. The results that we get with the models used in this work make apparent identical prediction quality and in some cases even better ones to the ones found in the state of the art, while offering a simplification of the mathematical formulation and the physical description of the flux transfer. This simplification thus transforms these models into calculation tools that can easily be used especially for the choice of quantities of ink that must be left on both sides of the document in order to obtain color matching

With the rapidly growing computational power of modern computers, physically based rendering has found its way into real world applications. Real-time simulations and renderings of fire and smoke had become one major research interest in modern video game industry, and will continue being one important research direction in computer graphics. To visually recreate realistic dynamic fire and smoke is a complicated problem. Furthermore, to solve the problem requires knowledge from various areas, ranged from computer graphics and image processing to computational physics and chemistry. Even though most of the areas are well-studied separately, when combined, new challenges will emerge. This thesis focuses on three aspects of the problem, dynamic, real-time and realism, to propose a solution in form of a GPGPU pipeline, along with its implementation. Three main areas with application in the problem are discussed in detail: fluid simulation, volumetric radiance estimation and volumetric rendering. The weights are laid upon the first two areas. The results are evaluated around the three aspects, with graphical demonstrations and performance measurements. Uniform grids are used with Finite Difference (FD) discretization scheme to simplify the computation. FD schemes are easy to implement in parallel, especially with ComputeShader, which is well supported in Unity engine. The whole implementation can easily be integrated into any real-world applications in Unity or other game engines that support DirectX 11 or higher.