Artificial vision is the problem of creating systems capable of processing visual information. A fundamental sub-problem of artificial vision is image segmentation, the problem of detecting a structure from a digital image. Examples of segmentation problems include the detection of a road from an aerial photograph or the determination of the boundaries of the brain's ventricles from medical imagery. The extraction of structures allows for subsequent higher-level cognitive tasks. One of them is shape comparison. For example, if the brain ventricles of a patient are segmented, can their shapes be used for diagnosis? That is to say, do the shapes of the extracted ventricles resemble more those of healthy patients or those of patients suffering from schizophrenia? This thesis deals with the problem of image segmentation and shape comparison in the mathematical framework of partial differential equations. The contribution of this thesis is threefold: 1. A technique for the segmentation of regions is proposed. A cost functional is defined for regions based on a non-parametric functional of the distribution of image intensities inside the region. This cost is constructed to favor regions that are homogeneous. Regions that are optimal with respect to that cost can be determined with limited user interaction. 2. The use of direction information is introduced for the segmentation of open curves and closed surfaces. A cost functional is defined for structures (curves or surfaces) by integrating a local, direction-dependent pattern detector along the structure. Optimal structures, corresponding to the best match with the pattern detector, can be determined using efficient algorithms. 3. A technique for shape comparison based on the Laplace equation is proposed. Given two surfaces, one-to-one correspondences are determined that allow for the characterization of local and global similarity measures. The local differences among shapes (resulting for example from a segmentation step) can be visualized for qualitative evaluation by a human expert. It can also be used for classifying shapes into, for example, normal and pathological classes.

M.Bibl. / Television producers form a unique user group that mainly requires information regarding audio-visual material in order to produce or to enhance a television programme Information services can contribute to the successful completion of a programme by making information available. The aim of this study is to determine whether information services can enhance information for producers by adding value. The question is also asked which value-added level of information is required. A literature study was done to -examine the term "value-added" in order to be able to apply it to the information needs of television producers; -study the work environment of television producers in order to determine their information needs. An empirical investigation was executed by means of a layered random sampling test. Structured interviews were conducted by means of a questionnaire with a random portion of the television producer corps of the SABC. Personal details were gathered, as well as the use of information sources and services within the SABC and to which value- added level of information they require for a production. Value-added levels were based on Taylor's value-added continuum which consists of information that is enhanced to level two, Information Knowledge, followed by level three, Productive Knowledge, which leads to level four, Action. A television production is completed in four phases, that is the planning and research phase, filming phase, editing phase and final mixing phase .. The results showed that during the planning and research phases television producers require access to all possible information sources and services within the SABC. The information specialist can add value to the first level of value adding. In certain cases the television producers require information during the editing phase, during which the information specialist can add value up to the third level. The results of the research were distilled into a matrix, structured to indicate the levels of added-value to the television producer. Recommendations were made in order to provide a better information service.