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IEEE international Conference on image processing (ICIP 2006)

作者： Takeda, Hiroyuki Farsitt, Sina Milanfar, Peyman Univ Calif Santa Cruz Dept Elect Engn Santa Cruz CA 95064 USA

ISBN: (纸本)9781424404810

We introduce a class of robust non-parametric estimation methods which are ideally suited for the reconstruction of signals and images from noise-corrupted or sparsely collected samples. The filters derived from this class are locally adapted kernels which take into account both the local density of the available samples, and the actual values of these samples. As such, they are automatically steered and adapted to both the given sampling "geometry', and the samples' "radiometry". As the framework we proposed does not rely upon specific assumptions about noise or sampling distributions, it is applicable to a wide class of problems including efficient image upscaling, high quality reconstruction of an image from as little as 15% of its (irregularly sampled) pixels, super-resolution from noisy and under-determined data sets, state of the art denoising of images corrupted by Gaussian and other noise, effective removal of compression artifacts;and more.

关键词： inverse problem image reconstruction piecewise polynomial approximation nonlinear estimation

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A Log-Euclidean polyaffine framework for locally rigid or affine registration

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3rd international workshop on Biomedical image Registration

作者： Arsigny, Vincent Commowick, Olivier Pennec, Xavier Ayache, Nicholas INRIA Sophia Epidaure Project F-06902 Sophia Antipolis France DOSISoft SA F-94230 Cachan France

ISBN: (纸本)3540356487

In this article, we focus on the parameterization of non-rigid geometrical deformations with a small number of flexible degrees of freedom. In previous work, we proposed a general framework called polyaffine to parameterize deformations with a small number of rigid or affine components, while guaranteeing the invertibility of global deformations. However, this framework lacks some important properties: the inverse of a polyaffine transformation is not polyaffine in general, and the polyaffine fusion of affine components is not invariant with respect to a change of coordinate system. We present here a novel general framework, called Log-Euclidean polyaffine, which overcomes these defects. We also detail a simple algorithm, the Fast Polyaffine Transform, which allows to compute very efficiently Log-Euclidean polyaffine transformations and their inverses on a regular grid. The results presented here on real 3D locally affine registration suggest that our novel framework provides a general and efficient way of fusing local rigid or affine deformations into a global invertible transformation without introducing artifacts, independently of the way local deformations are first estimated.

关键词： image processing

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A new generic texture synthesis approach for enhanced H.264/MPEG4-AVC video coding

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9th international workshop on Visual Content processing and Representation

作者： Ndjiki-Nya, Patrick Stueber, Christoph Wiegand, Thomas Fraunhofer Heinrich Hertz Inst Image Proc Dept Image Commun Grp D-10587 Berlin Germany

ISBN: (纸本)3540335781

A new generic texture synthesis approach, which is inspired by the work of Kwatra et al. [1], is presented in this paper. The approach is hierarchical, non-parametric, patch-based and for that applicable to a large class of spatio-temporal textures with and without local motion activity. In this work. it is shown, how the new texture synthesizer can be integrated into a content-based video coding framework. That is, the decoder reconstructs textures like water, grass, etc. that are usually very costly to encode. For that, the new texture synthesizer in conjunction with side information that is generated by the encoder is required. The reconstruction of above-mentioned textures at the decoder side basically corresponds to stuffing holes in a video sequence. Spurious edges are thereby avoided by using graph cuts to generate irregular contours at transitions between natural and synthetic textures and preferably place them (the contours) in high-frequency regions. where they are less visible.

关键词： Pattern recognition

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Evaluation of similarity measures for non-rigid registration

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3rd international workshop on Biomedical image Registration, WBIR 2006

作者： Škerl, Darko Likar, Boštjan Pernuš, Franjo University of Ljubljana Faculty of Electrical Engineering Tržaška 25 1000 Ljubljana Slovenia

ISBN: (纸本)3540356487

In this paper we propose a protocol for the evaluation of similarity measures for non-rigid registration, The protocol is feasible for the evaluation of non-rigid registration in which the deformation model is based on a set of regularly or irregularly distributed corresponding point pairs. The proposed protocol is able to deduce five properties of the similarity measure for each point pair of the deformation model, so that local or global estimation of the similarity measure properties can be derived. The feasibility of the proposed protocol was demonstrated on a popular deformation model based on B-splines, on six similarity measures, and on the "gold standard" CT and MR images of three spine vertebrae and three MR T1 and T2 images of the head. © Springer-Verlag Berlin Heidelberg 2006.

关键词： image processing

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Fast Polygonal approximation Based on Genetic Algorithms

Fast Polygonal Approximation Based on Genetic Algorithms

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international Conference on Computer and Information Science (ACIS)

作者： Yao-Hong Tsai Department of Information Management Hsuan Chuang University Hsinchu Taiwan

A fast algorithm is proposed for polygonal approximation of a digitized curve based on genetic evolution. The polygon is represented by a set of dominant points. The dominant points are identified as the points on the curve with local maximum curvatures. The optimization problem for the digitized curve with the approximating polygon is employing the genetic algorithm. Thus, a chromosome is used to represent a polygon. The break point detection on the chromosome is conducted to reduce the computations for optimization. Experimental results are included to show the effectiveness of this method

关键词： Genetic algorithms Shape Biological cells approximation algorithms Pattern recognition image processing Smoothing methods Evolutionary computation Information management image segmentation

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Using non-Parametric Kernel to Segment and Smooth images Simultaneously

Using Non-Parametric Kernel to Segment and Smooth Images Sim...

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IEEE international Conference on image processing

作者： Weihong Guo Yunmei Chen Department of Mathematics University of Florida Gainesville FL USA

Piecewise constant and piecewise smooth Mumford-Shah (MS) models have been widely studied and used for image segmentation. More complicated than piecewise constant MS, global Gaussian intensity distribution within each partitioned region has also been studied. However, all these frameworks are limited in power and robustness in finding objects whose interiors have high noise level and/or complex multi-modal intensity distribution. To overcome these drawbacks,we propose a non-parametric kernel based model which is able to simultaneously segment and smooth images without adding extra smoothing terms. At each point within each partitioned smooth region, a Gaussian kernel with mean the intensity of the given to-be-segmented image at this point and a small local variance depending on the location is applied to create a nonparametric intensity statistics approximation. To save computation, a quadratic kernel involving simple calculation could replace the Gaussian kernel that involves expensive exponential calculation. We demonstrate the superiority of proposed model over other models by showing segmentation results from various images with different levels and types of noise.

关键词： Kernel image segmentation Noise level Smoothing methods Gaussian noise Mathematical model Noise robustness Statistics Active contours

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Towards restoring historic documents degraded over time

Towards restoring historic documents degraded over time

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international workshop on Document image Analysis for Libraries

作者： F. Drira Laboratoire d'Informatique en image et Systéme d'Information LIRIS UMR 5205 du CNRS-INSA de LYON France

Resorting to restoration techniques for heritage documents becomes an increasingly urgent need. In fact, these valuable resources for human being are subject to several types of degradations limiting their use. A proposed solution to this problem is the application of restoration techniques on the digital copy of the originally degraded document. This would improve human readability and allow further application of image processing techniques. Hence identifying a typology of different types of image degradation is of primary concern for use in restoration techniques. Our main contributions in this paper are twofold. In the first instance, we propose a typology for different types of degradation of old document images. Our proposed typology is lead by the type of image processing undertaken in the course of virtual restoration. The second contribution is to develop a restoration method treating specific document degradation: "ink bleed-through". The proposed method is a non-supervised segmentation method. It is based on a recursive segmentation approach applied to the principal component analysis space. As an illustration, a scheme of "ink bleed-through" removal of the provided document images by the archive of "Chatillon-Chalaronne" is presented. Experiments conducted on these real ancient document images illustrate the effectiveness of our proposed method

关键词： Degradation image restoration image converters Software libraries image processing local government Internet Humidity image segmentation Character recognition

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Visual Shapes of Silhouette Sets

Visual Shapes of Silhouette Sets

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international Symposium on 3D Data processing Visualization and Transmission

作者： Jean-Sebastien Franco Marc Lapierre Edmond Boyer GRAVIR-INRIA Rhône-Alpes Saint Ismier France

Shape from silhouette methods are extensively used to model dynamic and non-rigid objects using binary foreground-background images. Since the problem of reconstructing shapes from silhouettes is ambiguous, a number of solutions exist and several approaches only consider the one with a maximal volume, called the visual hull. However, the visual hull is not always a good approximation of shapes, in particular when observing smooth surfaces with few cameras. In this paper, we consider instead a class of solutions to the silhouette reconstruction problem that we call visual shapes. Such a class includes the visual hull, but also better approximations of the observed shapes which can take into account local assumptions such as smoothness, among others. Our contributions with respect to existing works is first to identify silhouette consistent shapes different from the visual hull, and second to give a practical way to estimate such shapes in real time. Experiments on various sets of data including human body silhouettes are shown to illustrate the principle and the interests of visual shapes.

关键词： Shape Surface reconstruction image reconstruction Cameras Humans Robustness Yield estimation Topology Digital images Graphics

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non-local quasi-linear parabolic equations

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RUSSIAN MATHEMATICAL SURVEYS 2005年第6期60卷 1021-1033页

作者： Amann, H Univ Zurich Inst Math CH-8006 Zurich Switzerland

This is a survey of the most common approaches to quasi-linear parabolic evolution equations, a discussion of their advantages and drawbacks, and a presentation of an entirely new approach based on maximal L-p regularity. The general results here apply, above all, to parabolic initial-boundary value problems that are non-local in time. This is illustrated by indicating their relevance for quasi-linear parabolic equations with memory and, in particular, for time-regularized versions of the Perona-Malik equation of image processing.

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Robust nonrigid multimodal image registration using local frequency maps 1

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19th international Conference on Information processing in Medical Imaging, IPMI 2005

作者： Jian, Bing Vemuri, Baba C. Marroquin, José L. Department of Computer and Information Science and Engineering University of Florida Gainesville FL 32611 United States Centro de Investigacion en Matematicas A.C.Apostado Postal 402 Guanajuato Mexico 36020 Mexico

ISBN: (数字)9783540316763

ISBN: (纸本)9783540265450

Automatic multi-modal image registration is central to numerous tasks in medical imaging today and has a vast range of applications e.g., image guidance, atlas construction, etc. In this paper, we present a novel multi-modal 3D non-rigid registration algorithm where in 3D images to be registered are represented by their corresponding local frequency maps efficiently computed using the Riesz transform as opposed to the popularly used Gabor filters. The non-rigid registration between these local frequency maps is formulated in a statistically robust framework involving the minimization of the integral squared error a.k.a. L2E (L2 error). This error is expressed as the squared difference between the true density of the residual (which is the squared difference between the non-rigidly transformed reference and the target local frequency representations) and a Gaussian or mixture of Gaussians density approximation of the same. The non-rigid transformation is expressed in a B-spline basis to achieve the desired smoothness in the transformation as well as computational efficiency. The key contributions of this work are (i) the use of Riesz transform to achieve better efficiency in computing the local frequency representation in comparison to Gabor filter-based approaches, (ii) new mathematical model for local-frequency based non-rigid registration, (iii) analytic computation of the gradient of the robust non-rigid registration cost function to achieve efficient and accurate registration. The proposed non-rigid L2E-based registration is a significant extension of research reported in literature to date. We present experimental results for registering several real data sets with synthetic and real non-rigid misalignments. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Imaging systems

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