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Deconvolution Algorithm (deconvolution + algorithm)
Selected AbstractsColor Separation in Forensic Image ProcessingJOURNAL OF FORENSIC SCIENCES, Issue 1 2006Charles E. H. Berger Ph.D. ABSTRACT: In forensic image processing, it is often important to be able to separate a feature from an interfering background or foreground, or to demonstrate colors within an image to be different from each other. In this study, a color deconvolution algorithm that could accomplish this task is described, and it is applied to color separation problems in document and fingerprint examination. Subtle color differences (sometimes invisible to the naked eye) are found to be sufficient, which is demonstrated successfully for several cases where color differences were shown to exist, or where colors were removed from the foreground or background. The software is available for free in the form of an Adobe® Photoshop® -compatible plug-in. [source] Absolute quantification of cerebral blood flow in normal volunteers: Correlation between Xe-133 SPECT and dynamic susceptibility contrast MRIJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2007Linda Knutsson PhD Abstract Purpose To compare absolute cerebral blood flow (CBF) estimates obtained by dynamic susceptibility contrast MRI (DSC-MRI) and Xe-133 SPECT. Materials and Methods CBF was measured in 20 healthy volunteers using DSC-MRI at 3T and Xe-133 SPECT. DSC-MRI was accomplished by gradient-echo EPI and CBF was calculated using a time-shift-insensitive deconvolution algorithm and regional arterial input functions (AIFs). To improve the reproducibility of AIF registration the time integral was rescaled by use of a venous output function. In the Xe-133 SPECT experiment, Xe-133 gas was inhaled over 8 minutes and CBF was calculated using a biexponential analysis. Results The average whole-brain CBF estimates obtained by DSC-MRI and Xe-133 SPECT were 85 ± 23 mL/(min 100 g) and 40 ± 8 mL/(min 100 g), respectively (mean ± SD, n = 20). The linear CBF relationship between the two modalities showed a correlation coefficient of r = 0.76 and was described by the equation CBF(MRI) = 2.4 · CBF(Xe),7.9 (CBF in units of mL/(min 100 g)). Conclusion A reasonable positive linear correlation between MRI-based and SPECT-based CBF estimates was observed after AIF time-integral correction. The use of DSC-MRI typically results in overestimated absolute perfusion estimates and the present study indicates that this trend is further enhanced by the use of high magnetic field strength (3T). J. Magn. Reson. Imaging 2007;26:913,920. © 2007 Wiley-Liss, Inc. [source] Parallel deconvolution of large 3D images obtained by confocal laser scanning microscopyMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2010Piotr Pawliczek Abstract Various deconvolution algorithms are often used for restoration of digital images. Image deconvolution is especially needed for the correction of three-dimensional images obtained by confocal laser scanning microscopy. Such images suffer from distortions, particularly in the Z dimension. As a result, reliable automatic segmentation of these images may be difficult or even impossible. Effective deconvolution algorithms are memory-intensive and time-consuming. In this work, we propose a parallel version of the well-known Richardson,Lucy deconvolution algorithm developed for a system with distributed memory and implemented with the use of Message Passing Interface (MPI). It enables significantly more rapid deconvolution of two-dimensional and three-dimensional images by efficiently splitting the computation across multiple computers. The implementation of this algorithm can be used on professional clusters provided by computing centers as well as on simple networks of ordinary PC machines. Microsc. Res. Tech., 2010. © 2009 Wiley-Liss, Inc. [source] Thick gas discs in faint dwarf galaxiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2010Sambit Roychowdhury ABSTRACT We determine the intrinsic axial ratio distribution of the gas discs of extremely faint MB < ,14.5 dwarf irregular galaxies. We start with the measured (beam corrected) distribution of apparent axial ratios in the H i 21-cm images of dwarf irregular galaxies observed as part of the Faint Irregular Galaxy GMRT Survey (FIGGS). Assuming that the discs can be approximated as oblate spheroids, the intrinsic axial ratio distribution can be obtained from the observed apparent axial ratio distribution. We use a variety of methods to do this, and our final results are based on using Lucy's deconvolution algorithm. This method is constrained to produce physically plausible distributions, and also has the added advantage of allowing for observational errors to be accounted for. While one might a priori expect that gas discs would be thin (because collisions between gas clouds would cause them to quickly settle down to a thin disc), we find that the H i discs of faint dwarf irregulars are quite thick, with mean axial ratio ,q,, 0.6. While this is substantially larger than the typical value of ,0.2 for the stellar discs of large spiral galaxies, it is consistent with the much larger ratio of velocity dispersion to rotational velocity (,/vc) in dwarf galaxy H i discs as compared to that in spiral galaxies. Our findings have implications for studies of the mass distribution and the Tully,Fisher relation for faint dwarf irregular galaxies, where it is often assumed that the gas is in a thin disc. [source] A ,bottom-up' approach for endo-PK/PD analysisBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 7 2006S. Neelakantan Abstract A ,bottom-up' PK/PD analysis approach employing system analysis principles of convolution/deconvolution and special nonparametric estimation procedures is presented to resolve the complex ,endo-PK/PD' of the endogenous form of recombinant drugs using erythropoietin (EPO) as an example. A novel cellular deconvolution algorithm is presented that facilitates the identification of the functional relationship between the variables involved in EPO's complex PK/PD. Five sheep each underwent two phlebotomies spaced 4,6 weeks apart when their hemoglobin levels were reduced from 12 g/dl to 3,4 g/dl. EPO levels and reticulocyte counts were frequently sampled. The data were analysed using end-constrained cubic splines. The rate of reticulocyte production was determined using the novel deconvolution methodology. The erythroid progenitor cells activation rate by EPO was estimated from the reticulocyte production rate using a lag-time parameter which determines the delay in the reticulocyte appearance in the blood relative to the activation of erythroid progenitors. Hysteresis minimization combined with cellular deconvolution was employed to determine the population PK/PD transduction function relating the progenitor activation rate to EPO concentrations in a nonparametric manner without assuming a specific structure. The proposed approach provides a rational informative starting point for developing parametric PK/PD models to resolve the complex endo-PK/PD of recombinant drugs. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||