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Resulting Images (resulting + image)
Selected AbstractsHigh-resolution imaging using integrated optical systemsINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 2 2004S. Prasad Abstract Certain optical aberrations, such as defocus, can significantly degrade the signal collected by an imaging system, producing images with low resolution. In images with depth-dependent detail, such degradations are difficult to remove due to their inherent spatially varying nature. In 1995, Dowski and Cathey introduced the concept of wavefront coding to extend the depth of field. They showed that wavefront coding and decoding enables quality control of such images using integrated optical-digital imaging systems. With wavefront coding, a high-resolution image can be efficiently obtained without the need to resort to expensive algorithms for spatially varying restoration. In this article, we discuss a novel and effective multiple-design-parameter approach for optimizing the processes of encoding and decoding the wavefront phase in integrated optical-digital imaging systems. Our approach involves the use of information metrics, such as the Strehl ratio and Fisher information, for determining the optimal pupil-phase distribution for which the resulting image is insensitive to certain aberrations, such as focus errors. The effectiveness of this approach is illustrated with a number of numerical simulation experiments, and applications to the development of iris recognition systems with high-resolution capabilities are briefly discussed. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 14, 67,74, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20009 [source] Image-based EPI ghost correction using an algorithm based on projection onto convex sets (POCS)MAGNETIC RESONANCE IN MEDICINE, Issue 4 2002K.J. Lee Abstract This work describes the use of a method, based on the projection onto convex sets (POCS) algorithm, for reduction of the N/2 ghost in echo-planar imaging (EPI). In this method, ghosts outside the parent image are set to zero and a model k -space is obtained from the Fourier transform (FT) of the resulting image. The zeroth- and first-order phase corrections for each line of the original k -space are estimated by comparison with the corresponding line in the model k -space. To overcome problems of phase wrapping, the first-order phase corrections for the lines of the original k -space are estimated by registration with the corresponding lines in the model k -space. It is shown that applying these corrections will result in a reduction of the ghost, and that iterating the process will result in a convergence towards an image in which the ghost is minimized. The method is tested on spin-echo EPI data. The results show that the method is robust and remarkably effective, reducing the N/2 ghost to a level nearly comparable to that achieved with reference scans. Magn Reson Med 47:812,817, 2002. © 2002 Wiley-Liss, Inc. [source] A generalization of the mass-sheet degeneracy producing ring-like artefacts in the lens mass distributionMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008J. Liesenborgs ABSTRACT The inversion of a gravitational lens system is, as is well known, plagued by the so-called mass-sheet degeneracy: one can always rescale the density distribution of the lens and add a constant-density mass sheet such that the, also properly rescaled, source plane is projected on to the same observed images. For strong lensing systems, it is often claimed that this degeneracy is broken as soon as two or more sources at different redshifts are available. This is definitely true in the strict sense that it is then impossible to add a constant-density mass sheet to the rescaled density of the lens without affecting the resulting images. However, often one can easily construct a more general mass distribution , instead of a constant-density sheet of mass , which gives rise to the same effect: a uniform scaling of the sources involved without affecting the observed images. We show that this can be achieved by adding one or more circularly symmetric mass distributions, each with its own centre of symmetry, to the rescaled mass distribution of the original lens. As it uses circularly symmetric distributions, this procedure can lead to the introduction of ring-shaped features in the mass distribution of the lens. In this paper, we show explicitly how degenerate inversions for a given strong lensing system can be constructed. It then becomes clear that many constraints are needed to effectively break this degeneracy. [source] The Human Protein Atlas,a tool for pathology,THE JOURNAL OF PATHOLOGY, Issue 4 2008F Pontén Abstract Tissue-based diagnostics and research is incessantly evolving with the development of new molecular tools. It has long been realized that immunohistochemistry can add an important new level of information on top of morphology and that protein expression patterns in a cancer may yield crucial diagnostic and prognostic information. We have generated an immunohistochemistry-based map of protein expression profiles in normal tissues, cancer and cell lines. For each antibody, altogether 708 spots of tissues and cells are analysed and the resulting images and data are presented as freely available in the Human Protein Atlas (www.proteinatlas.org). The new version 4 of the atlas, including more than 5 million images of immunohistochemically stained tissues and cells, is based on 6122 antibodies, representing 5011 human proteins encoded by approximately 25% of the human genome. The gene-centric database includes a putative classification of proteins in various protein classes, both functional classes, such as kinases or transcription factors and project-related classes, such as candidate genes for cancer or cardiovascular diseases. For each of the internally generated antibodies, the exact antigen sequence is presented, together with a visualization of application-specific validation data, including a protein array assay, western blot analysis, immunohistochemistry and, in most cases, immunofluorescent-based confocal microscopy. The updated version also includes new search algorithms to allow complex queries regarding expression profiles, protein classes and chromosome location. Thus, the presented Human Protein Atlas provides a resource for pathology-based biomedical research, including protein science and biomarker discovery. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Three-dimensional, multi-offset ground-penetrating radar imaging of archaeological targetsARCHAEOLOGICAL PROSPECTION, Issue 2 2008Adam D. Booth Abstract The efficacy of ground penetrating radar (GPR) methods is inhibited when surveying over a target that is structurally complex and/or hosted within attenuative media. Recent research has documented the ability of certain seismic methods to improve imaging using GPR. For imaging complex targets, three-dimensional acquisition and migration methods are applied. For attenuative sites, signal-to- noise ratio (SNR) may be boosted on acquisition of multi-offset data. We present results from an integrated three-dimensional multi-offset survey over a Romano-British villa at Groundwell Ridge, near Swindon, UK. Data were acquired within a grid of dimension 21,m,×,14,m, using a single-channel PulseEKKO GPR system equipped with common-offset (CO) 450,MHz antennas. To satisfy criteria for three-dimensional migration, the sample density over the grid was 0.05,×,0.05,m2. A smaller grid of three-dimensional multi-offset data was acquired, with fold-of-cover 2200%, targeting a low SNR section of data. The spatial resolution and SNR in the resulting images of the target are greatly improved compared with data acquired using a more conventional survey method. However, this improvement may not be justified by the greatly increased (some 10 times) fieldwork effort required to obtain three-dimensional multi-offset data. We therefore investigate a means of improving the efficiency of three-dimensional GPR surveying by applying a simple trace interpolation method to recover three-dimensional acquisition criteria. This trial suggests that, at this site, three-dimensional data can be simulated from a grid of pseudo-three-dimensional data, sampled at 0.05,×,0.25,m2. In this way, high quality images of an archaeological target can be obtained with minimal increase to survey effort. We hope that, on the basis of this work, three-dimensional and multi-offset acquisitions will be more readily considered for archaeological GPR investigations. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||