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Thesis (DTech(Business Informatics))--Cape Technikon, Cape Town, 1997 / Modem applications in computer graphics and telecommunications command high performance filtering and smoothing to be implemented. The recent development of a new class of max-min selectors for digital image processing is investigated with special emphasis on the practical implications for hardware and software design.

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M.Phil. / Organisations and organisational actions have a profound influence on the lives of modern day citizens. This influence is most often recognised and the magnitude felt when these organisations cease to exist, which is occurring with increasing frequency. Literature related to this occurrence increasingly suggests that a strong organisation identity is paramount to organisational sustainability. Organisation identity per se has been largely under researched in organisations, literature and research with the majority of organisational work on the phenomenon having been conducted in the public relations and marketing domains. In terms of literature and research, the knowledge base is largely limited to conceptual debates with very few empirical studies aimed at building theory and advancing the existing knowledge on the subject. This perceived lack of empirical research and critical study of organisation identity can probably be attributed to its ambiguous nature, the lack of a strong theoretical base and the debate surrounding the conceptualisation of identity as being stable versus being fluid. The purpose of the current study was to confirm, empirically, the presence of identity in an organisation and then to detect the changes, if any, that have taken place in the organisation's identity over time. A brief literature review was undertaken to set the context for the study and to provide a basis from which to commence with the study. The notions of individual identity, social identity, corporate image, corporate identity, corporate branding and organisational culture were reviewed in an attempt to distinguish the organisation identity concept from these. For the purpose of providing a context for the study, brief attention was also directed to the different intellectual traditions on organisation identity, the existing empirical studies and the challenges associated with studying the phenomenon. In order to arrive at an informed research question, it was concluded that organisation identity is concerned with the organisation as entity and that organisation identity is a x socially-constructed, sub-conscious phenomenon which becomes salient during periods of change. Furthermore, organisation identity refers to who and what the organisation is and refers to those features of the organisation that are core, distinctive and enduring. Based on the ambiguous nature of the organisation identity phenomenon and the fact that it is tacitly held and is constructed over time by the individuals that experience it, it was concluded that the phenomenon lends itself to qualitative research. The study was approached from within the knowledge framework provided by the classical school of thought on organisation identity which views organisation identity as being those features which the members of the organisation believe to be core, distinctive and enduring. Use was made of an open-ended, self administered questionnaire, which included two different techniques. The questionnaire required of respondents to describe the organisation's answer to the question "Who am I?" using the Twenty Statements Test as well as to describe the organisation through the use of a metaphor and to provide reasons for choosing a specific metaphor for both the past and the present. The research setting chosen was an English primary school and the questionnaire was administered to all the employees of the organisation (86 in total). A total of 54 responses were received and the data subsequently analysed. Use was made of open coding and the development of themes and the data was scrutinised to identify themes and categories of interest. Relevant quotes as used by respondents and which were illustrative of a specific theme were then utilised to describe the most prominent themes. Statements that were closely related were included as part of the same theme, where applicable. When viewing the current study against the background of the classical definition of organisation identity, an argument was made for the future omission of the "core" feature and the inclusion of the unifying nature of organisation identity. When operationalising identity as being the organisation's distinctive features as presented in xi terms of the answer to the question "Who am I?" it was once again apparent that this is a valid means of determining and surfacing organisation identity. The organisational sense-of-identity was confirmed by the fact that some respondents made specific reference to identity. The data was viewed using these conceptualisations of identity and it was concluded that the organisation did posses an identity and that changes had taken place in this identity over time albeit not fundamental in nature. Attention was also devoted to the dynamic nature of organisation identity and the links between identity and the organisational life cycle stage as well as the effect of size on organisation identity. Based on the findings, it was argued that the time has come to rigorously study organisation identity as a phenomenon in its own right and to further the empirical knowledge base of the field in order to inform theory development. The study concluded that organisation identity has significant implications for the management of the school and indeed for other organisations where similar situations prevail. It was argued that the management of the organisation should take action to harness the advantages of the relatively strong identity of the organisation as a means of competitive advantage. In the final instance it was concluded that organisation identity might prove to be the answer to ensuring organisational longevity in a world characterised by organisational demise.

Many applications of image processing require the initial segmentation of the image by means of grey-level thresholding. In this thesis, the problems of automatic threshold selection and evaluation are addressed in order to find a universally applicable thresholding method. Three previously proposed threshold selection techniques are investigated, and two new methods are introduced. The results of applying these methods to several different images are evaluated using two threshold evaluation techniques, one subjective and one quantitative. It is found that no threshold selection technique is universally acceptable, as different methods work best with different images and applications

Image-based face recognition has attained wide applications during the past decades in commerce and law enforcement areas, such as mug shot database matching, identity authentication, and access control. Existing face recognition techniques (e.g., Eigenface, Fisherface, and Elastic Bunch Graph Matching, etc.), however, do not perform well when the following case inevitably exists. The case is that, due to some variations in imaging conditions, e.g., pose and illumination changes, face images of the same person often have different appearances. These variations make face recognition techniques much challenging. With this concern in mind, the objective of my research is to develop robust face recognition techniques against variations. This thesis addresses two main variation problems in face recognition, i.e., pose and illumination variations. To improve the performance of face recognition systems, the following methods are proposed: (1) a face feature extraction and representation method using non-uniformly selected Gabor convolution features, (2) an illumination normalization method using adaptive region-based image enhancement for face recognition under variable illumination conditions, (3) an eye detection method in gray-scale face images under various illumination conditions, and (4) a virtual pose generation method for pose-invariant face recognition. The details of these proposed methods are explained in this thesis. In addition, we conduct a comprehensive survey of the existing face recognition methods. Future research directions are pointed out. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The goal of this thesis is to gain a deep understanding of inverse problems arising from 2D image and 3D surface reconstruction, and to design effective techniques for solving them. Both computational and theoretical issues are studied and efficient numerical algorithms are proposed. The first part of this thesis is concerned with the recovery of 2D images, e.g., de-noising and de-blurring. We first consider implicit methods that involve solving linear systems at each iteration. An adaptive Huber regularization functional is used to select the most reasonable model and a global convergence result for lagged diffusivity is proved. Two mechanisms---multilevel continuation and multigrid preconditioning---are proposed to improve efficiency for large-scale problems. Next, explicit methods involving the construction of an artificial time-dependent differential equation model followed by forward Euler discretization are analyzed. A rapid, adaptive scheme is then proposed, and additional hybrid algorithms are designed to improve the quality of such processes. We also devise methods for more challenging cases, such as recapturing texture from a noisy input and de-blurring an image in the presence of significant noise. It is well-known that extending image processing methods to 3D triangular surface meshes is far from trivial or automatic. In the second part of this thesis we discuss techniques for faithfully reconstructing such surface models with different features. Some models contain a lot of small yet visually meaningful details, and typically require very fine meshes to represent them well; others consist of large flat regions, long sharp edges (creases) and distinct corners, and the meshes required for their representation can often be much coarser. All of these models may be sampled very irregularly. For models of the first class, we methodically develop a fast multiscale anisotropic Laplacian (MSAL) smoothing algorithm. To reconstruct a piecewise smooth CAD-like model in the second class, we design an efficient hybrid algorithm based on specific vertex classification, which combines K-means clustering and geometric a priori information. Hence, we have a set of algorithms that efficiently handle smoothing and regularization of meshes large and small in a variety of situations. / Science, Faculty of / Mathematics, Department of / Graduate

Submitted in fulfillment of the requirements for the Master's Degree in Information and Communication Technology, Durban, University of Technology, Durban, South Africa, 2017. / The topic of colour image segmentation has been and still is a hot issue in areas such as computer vision and image processing because of its wide range of practical applications. The urge has led to the development of numerous colour image segmentation algorithms to extract salient objects from colour images. However, because of the diverse imaging conditions in varying application domains, accuracy and robustness of several state-of-the-art colour image segmentation algorithms still leave room for further improvement. This dissertation reports on the development of a new image segmentation algorithm based on perceptual colour difference saliency along with binary morphological operations. The algorithm consists of four essential processing stages which are colour image transformation, luminance image enhancement, salient pixel computation and image artefact filtering. The input RGB colour image is first transformed into the CIE L*a*b colour image to achieve perceptual saliency and obtain the best possible calibration of the transformation model. The luminance channel of the transformed colour image is then enhanced using an adaptive gamma correction function to alleviate the adverse effects of illumination variation, low contrast and improve the image quality significantly. The salient objects in the input colour image are then determined by calculating saliency at each pixel in order to preserve spatial information. The computed saliency map is then filtered using the morphological operations to eliminate undesired factors that are likely present in the colour image. A series of experiments was performed to evaluate the effectiveness of the new perceptual colour difference saliency algorithm for colour image segmentation. This was accomplished by testing the algorithm on a large set of a hundred and ninety images acquired from four distinct publicly available benchmarks corporal. The accuracy of the developed colour image segmentation algorithm was quantified using four widely used statistical evaluation metrics in terms of precision, F-measure, error and Dice. Promising results were obtained despite the fact that the experimental images were selected from four different corporal and in varying imaging conditions. The results have indeed demonstrated that the performance of the newly developed colour image segmentation algorithm is consistent with an improved performance compared to a number of other saliency and non- saliency state-of-the-art image segmentation algorithms. / M

Objective: To determine the association between body image dissatisfaction (BID) and depressive symptoms in adolescents from a school in Lima, Peru. Methods: A cross-sectional study was performed through a census of 875 high-school students, aged 13 to 17 years, from a school in Lima. Participants completed a survey containing the Body Shape Questionnaire (BSQ) and the Patient Health Questionnaire-9 (PHQ-9). Data regarding demographics, alcohol and tobacco use, self-esteem, and family history of depression were also obtained. To identify associated factors, Poisson regression with robust variance was used. Prevalence ratios with 95% confidence intervals were calculated. Results: Of the 875 adolescents, 55.8% were male. The mean age was 14.161.5 years. Depressive symptoms were observed in 19.9% of participants. An association between BID and depressive symptoms was found. Alcohol and tobacco use were also associated with the outcome of interest. Conclusions: Teens who had BID were 3.7 times more likely to report depressive symptoms. Additionally, those who used tobacco or alcohol were 1.5 and 1.4 times more likely to have depressive symptoms, respectively. Further studies targeting other populations and using longitudinal designs are recommended.

In this thesis, estimation of motion from an image sequence is investigated. The emphasis is on the novel use of motion model for describing two dimensional motion. Special attention is directed towards general motion models which are not restricted to translational motion. In contrast to translational motion, the 2-D motion is described by the model using motion parameters. There are two major areas which can benefit from the study of general motion model. The first one is image sequence processing and compression. In this context, the use of motion model provides a more compact description of the motion information because the model can be applied to a larger area. The second area is computer vision. The general motion parameters provide clues to the understanding of the environment. This offers a simpler alternative to techniques such as optical flow analysis. A direct approach is adopted here to estimate the motion parameters directly from an image sequence. This has the advantage of avoiding the error caused by the estimation of optical flow. A differential method has been developed for the purpose. This is applied in conjunction with a multi-resolution scheme. An initial estimate is obtained by applying the algorithm to a low resolution image. The initial estimate is then refined by applying the algorithm to image of higher resolutions. In this way, even severe motion can be estimated with high resolution. However, the algorithm is unable to cope with the situation of multiple moving objects, mainly because of the least square estimator used. A second algorithm, inspired by the Hough transform, is therefore developed to estimate the motion parameters of multiple objects. By formulating the problem as an optimization problem, the Hough transform is computed only implicitly. This drastically reduces the computational requirement as compared with the Hough transform. The criterion used in optimization is a measure of the degree of match between two images. It has been shown that the measure is a well behaving function in the vicinity of the motion parameter vectors describing the motion of the objects, depending on the smoothness of the images. Therefore, smoothing an image has the effect of allowing longer range motion to be estimated. Segmentation of the image according to motion is achieved at the same time. The ability to estimate general motion in the situation of multiple moving objects represents a major step forward in 2-D motion estimation. Finally, the application of motion compensation to the problem of frame rate conversion is considered. The handling of the covered and uncovered background has been investigated. A new algorithm to obtain a pixel value for the pixels in those areas is introduced. Unlike published algorithms, the background is not assumed stationary. This presents a major obstacle which requires the study of occlusion in the image. During the research, the art of motion estimation hcis been advanced from simple motion vector estimation to a more descriptive level: The ability to point out that a certain area in an image is undergoing a zooming operation is one example. Only low level information such as image gradient and intensity function is used. In many different situations, problems are caused by the lack of higher level information. This seems to suggest that general motion estimation is much more than using a general motion model and developing an algorithm to estimate the parameters. To advance further the state of the art of general motion estimation, it is believed that future research effort should focus on higher level aspects of motion understanding.