Multiresolution image modelling and estimation

Multiresolution representations make explicit the notion of scale in images, and facilitate the combination of information from different scales. To date, however, image modelling and estimation schemes have not exploited such representations and tend rather to be derived from two- dimensional extensions of traditional one-dimensional signal processing techniques. In the causal case, autoregressive (AR) and ARMA models lead to minimum mean square error (MMSE) estimators which are two-dimensional variants of the well-established Kalman filter. Noncausal approaches tend to be transform-based and the MMSE estimator is the two- dimensional Wiener filter. However, images contain profound nonstationarities such as edges, which are beyond the descriptive capacity of such signal models, and defects such as blurring (and streaking in the causal case) are apparent in the results obtained by the associated estimators. This thesis introduces a new multiresolution image model, defined on the quadtree data structure. The model is a one-dimensional, first-order gaussian martingale process causal in the scale dimension. The generated image, however, is noncausal and exhibits correlations at all scales unlike those generated by traditional models. The model is capable of nonstationary behaviour in all three dimensions (two position and one scale) and behaves isomorphically but independently at each scale, in keeping with the notion of scale invariance in natural images. The optimal (MMSE) estimator is derived for the case of corruption by additive white gaussian noise (AWGN). The estimator is a one-dimensional, first-order linear recursive filter with a computational burden far lower than that of traditional estimators. However, the simple quadtree data structure leads to aliasing and 'block' artifacts in the estimated images. This could be overcome by spatial filtering, but a faster method is introduced which requires no additional multiplications but involves the insertion of some extra nodes into the quadtree. Nonstationarity is introduced by a fast, scale-invariant activity detector defined on the quadtree. Activity at all scales is combined in order to achieve noise rejection. The estimator is modified at each scale and position by the detector output such that less smoothing is applied near edges and more in smooth regions. Results demonstrate performance superior to that of existing methods, and at drastically lower computational cost. The estimation scheme is further extended to include anisotropic processing, which has produced good results in image restoration. An orientation estimator controls anisotropic filtering, the output of which is made available to the image estimator

Smiles and Tears

[Verse 1] When midst the day I meet That gentle smile of thine, Though still on me it turns most sweet, I scarce can call it mine; But when to me alone Your secret tears you show, Oh! Then I feel those tears my own, And claim them while they flow. Then still with bright looks bless The gay, the cold, the free; Give smiles to those who love you less, But keep your tears, keep your tears for me. [Verse 2] The snow of Jura’s steep Can smile in many a beam, Yet still in chains of coldness sleep, How bright soe’er it seem. But when some deep-felt ray, Whose touch is fire, appears, Oh! Then the smile is warm’d away, And, melting, turns to tears. Then still with bright looks bless The gay, the cold, the free; Gives smiles to those who love you less, But keep your tears for me

Microscopic resolution broadband dielectric spectroscopy

Results are presented for a non-contact measurement system capable of micron level spatial resolution. It utilises the novel electric potential sensor (EPS) technology, invented at Sussex, to image the electric field above a simple composite dielectric material. EP sensors may be regarded as analogous to a magnetometer and require no adjustments or offsets during either setup or use. The sample consists of a standard glass/epoxy FR4 circuit board, with linear defects machined into the surface by a PCB milling machine. The sample is excited with an a.c. signal over a range of frequencies from 10 kHz to 10 MHz, from the reverse side, by placing it on a conducting sheet connected to the source. The single sensor is raster scanned over the surface at a constant working distance, consistent with the spatial resolution, in order to build up an image of the electric field, with respect to the reference potential. The results demonstrate that both the surface defects and the internal dielectric variations within the composite may be imaged in this way, with good contrast being observed between the glass mat and the epoxy resin

Remote monitoring of biodynamic activity using electric potential sensors

Previous work in applying the electric potential sensor to the monitoring of body electrophysiological signals has shown that it is now possible to monitor these signals without needing to make any electrical contact with the body. Conventional electrophysiology makes use of electrodes which are placed in direct electrical contact with the skin. The electric potential sensor requires no cutaneous electrical contact, it operates by sensing the displacement current using a capacitive coupling. When high resolution body electrophysiology is required a strong (capacitive) coupling is used to maximise the collected signal. However, in remote applications where there is typically an air-gap between the body and the sensor only a weak coupling can be achieved. In this paper we demonstrate that the electric potential sensor can be successfully used for the remote sensing and monitoring of bioelectric activity. We show examples of heart-rate measurements taken from a seated subject using sensors mounted in the chair. We also show that it is possible to monitor body movements on the opposite side of a wall to the sensor. These sensing techniques have biomedical applications for non-contact monitoring of electrophysiological conditions and can be applied to passive through-the-wall surveillance systems for security applications

Bayesian Video Face Detection with Applications in Broadcasting

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Aligning research to meet policy objectives for migrant families: an example from Canada

<p>Abstract</p> <p>Background</p> <p>'Evidence-based policy making' for immigrants is a complicated undertaking. In striving toward this goal, federal Canadian partners created the <it>Metropolis Project </it>in 1995 to optimize a two-way transfer of knowledge (researchers – policy makers) within five Canadian Centres of Excellence focused on migrants newly arrived in Canada. Most recently, <it>Metropolis </it>federal partners, including the Public Health Agency of Canada, defined one of six research priority areas as, immigrant 'families, children, and youth'. In order to build on previous work in the partnership, we sought to determine what has been studied within this research-policy partnership about immigrant 'families, children, and youth' since its inception.</p> <p>Methods</p> <p>Annual reports and working papers produced in the five Centres of Excellence between 1996–2006 were culled. Data on academic works were extracted, results coded according to eleven stated federal policy priority themes, and analyzed descriptively.</p> <p>Results</p> <p>139 academic works were reviewed. All federal priority themes, but few specific policy questions were addressed. The greatest volume of policy relevant works were identified for <it>Services </it>(n = 42) and <it>Education and Cultural Identity </it>(n = 39) priority themes.</p> <p>Conclusion</p> <p>Research conducted within the last 10 years is available to inform certain, not all, federal policy questions. Greater specificity in federal priorities can be expected to more clearly direct future research within this policy-research partnership.</p