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Guided filter for adaptive persistence of ultrasound images

ICIC Express Letters, Part B: Applications 2013年第6期4卷 1597-1602页

作者： Guo, Dequan Yang, Hongyu Yin, Hao Liu, Dong Chyuan Zhang, Zhijie Key Laboratory of Fundamental Synthetic Vision Graphics and Image Science for National Defense Sichuan University No. 24 South Section 1 Yihuan Road Chengdu 610065 China Department of Mechanical Engineering Neijiang Vocational and Technical College No. 42 Dongtong Road Neijiang 641100 China College of Computer Science Sichuan University No. 24 South Section 1 Yihuan Road Chengdu 610065 China

Medical ultrasonic images often suffer from the electronics noise and speckle artifact, which degrade lesion detectability and increase the likelihood of misdiagnosis. In this paper, a legible and comprehensive method for ultrasonic image is proposed and it can be effective to suppress the noise and improve the images quality. Persistence technology based on temporal multi-frames is utilized to smooth the electronics noise and even lower speckle artifact. To reduce computing complexity, a sum table method and conjugate direction search approaches are applied to speed up estimation of motion vectors. Then, the guided image filter strategy is used to enhance the contrast and detail resolution for the processed image by persistence. The experimental results show that the proposed method is better in quantitative and qualitative perfomance, and enhances the ultrasound image in contrast with existing methods. © 2013 ICIC International.

关键词： Motion estimation

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Evaluation of fast 2D and 3D medical image retrieval approaches based on image miniatures

Evaluation of fast 2D and 3D medical image retrieval approac...

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2nd MICCAI International Workshop on Medical Content-Based Retrieval for Clinical Decision Support, MCBR-CDS 2011

作者： Donner, René Haas, Sebastian Burner, Andreas Holzer, Markus Bischof, Horst Langs, Georg Computational Image Analysis and Radiology Lab. Department of Radiology Medical University of Vienna Austria Institute for Computer Graphics and Vision Graz University of Technology Austria Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology Cambridge MA United States

ISBN: (纸本)9783642284595

The present work evaluates four medical image retrieval approaches based on features derived from image miniatures. We argue that due to the restricted domain of medical image data, the standardized acquisition protocols and the absence of a potentially cluttered background a holistic image description is sufficient to capture high-level image similarities. We compare four different miniature 2D and 3D descriptors and corresponding metrics, in terms of their retrieval performance: (A) plain miniatures together with euclidean distances in a k Nearest Neighbor based retrieval backed by kD-trees;(B) correlations of rigidly aligned miniatures, initialized using the kD-tree;(C) distribution fields together with the l1-norm;(D) SIFT-like histogram of gradients using the χ2-distance. We evaluate the approaches on two data sets: the ImageClef 2009 benchmark of 2D radiographs with the aim to categorize the images and a large set of 3D-CTs representing a realistic sample in a hospital PACS with the objective to estimate the location of the query volume. © 2012 Springer-Verlag.

关键词： Medical imaging

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Tablet versus phone: Depth perception in handheld augmented reality

Tablet versus phone: Depth perception in handheld augmented ...

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International Symposium on Mixed and Augmented Reality (ISMAR)

作者： Arindam Dey Graeme Jarvis Christian Sandor Gerhard Reitmayr University of South Australia Adelaide SA AU Magic Vision Laboratory University of South Australia Institute of Computer Graphics and Vision Graz University of Technology

Augmented Reality (AR) applications on mobile devices like smartphones and tablet computers have become increasingly popular. In this paper, for the first time in the AR domain, we present: (1) the influence of different handheld displays and (2) the exocentric depth perception. Unlike egocentric depth perception, exocentric depth perception has not been investigated in AR. We have selected a suitable vision-based tracking method for our user studies based on a set of evaluations. Then we have investigated the effect of display size and resolution through two user studies. One study investigated the effect of different displays on egocentric depth perception. The other study investigated the effect of displays on exocentric and ordinal depth perception. Interestingly, we noticed depth compression is less when using a mobile phone, while participants subjectively preferred a tablet. A similar effect was also noticed in exocentric depth perception. The tablet provided significantly better ordinal depth perception and faster response time than the mobile phone. In both of the studies, we found no effect of the AR X-ray visualization on depth perception. Both egocentric and exocentric distances were underestimated.

关键词： Visualization Mobile handsets Cameras Target tracking Mobile communication Estimation

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Classification of gothic and baroque architectural elements

Classification of gothic and baroque architectural elements

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International Conference on Systems, Signals and Image Processing, IWSSIP

作者： Gayane Shalunts Yll Haxhimusa Robert Sablatnig Institute of Computer Aided Automation Computer Vision Laboratory University of Technology Vienna Austria Institute of Computer Graphics and Algorithms Pattern Recognition and Image Processing Lab University of Technology Vienna Austria

Architectural elements are the components and details of buildings. Their unique set, combination, design, construction technique form the architectural style of buildings. Building facade classification by architectural styles is viewed as a task of classifying separate architectural structural elements. In the scope of building facade architectural style classification the current paper targets the problem of classification of Gothic and Baroque architectural elements called tracery, pediment and balustrade. Since certain gradient directions dominate on the shape of each architectural element, discrimination between dominating gradients means classification of architectural elements and thus architectural styles. We use local features to describe gradient directions. Our approach is based on clustering and learning of local features and yields a high classification rate.

关键词： Shape Three dimensional displays Visualization computer vision Histograms Windows

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Improving classifiers with unlabeled weakly-related videos

Improving classifiers with unlabeled weakly-related videos

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作者： Leistner, Christian Godec, Martin Schulter, Samuel Saffari, Amir Werlberger, Manuel Bischof, Horst Computer Vision Laboratory ETH Zurich Switzerland Institute for Computer Graphics and Vision TU Graz Austria Oxford Brookes University and Sony Computer Entertainment London United Kingdom

ISBN: (纸本)9781457703942

Current state-of-the-art object classification systems are trained using large amounts of hand-labeled images. In this paper, we present an approach that shows how to use unlabeled video sequences, comprising weakly-related object categories towards the target class, to learn better classifiers for tracking and detection. The underlying idea is to exploit the space-time consistency of moving objects to learn classifiers that are robust to local transformations. In particular, we use dense optical flow to find moving objects in videos in order to train part-based random forests that are insensitive to natural transformations. Our method, which is called Video Forests, can be used in two settings: first, labeled training data can be regularized to force the trained classifier to generalize better towards small local transformations. Second, as part of a tracking-by-detection approach, it can be used to train a general codebook solely on pair-wise data that can then be applied to tracking of instances of a priori unknown object categories. In the experimental part, we show on benchmark datasets for both tracking and detection that incorporating unlabeled videos into the learning of visual classifiers leads to improved results. © 2011 IEEE.

关键词： Classification (of information)

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Improving Classifiers with Unlabeled Weakly-Related Videos

Improving Classifiers with Unlabeled Weakly-Related Videos

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IEEE Conference on computer vision and Pattern Recognition

作者： Christian Leistner Martin Godec Samuel Schulter Amir Saffari Manuel Werlberger Horst Bischof Computer Vision Laboratory ETH Zurich Institute for Computer Graphics and Vision TU Graz Oxford Brookes University and Sony Computer Entertainment

ISBN: (纸本)9781457703942

关键词： Videos Target tracking Vegetation Training Optical imaging computer vision

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Planar roof surface segmentation using 3D vision 11

Planar roof surface segmentation using 3D vision

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19th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems, ACM SIGSPATIAL GIS 2011

作者： Meixner, Philipp Leberl, Franz Brédif, Mathieu Institute of Computer Graphics and Vision Graz University of Technology A-8010 Graz Austria MATIS Laboratory Institute Géographique Nationale Université Paris-Est 94165 Saint-Mandé Cedex France

ISBN: (纸本)9781450310314

Internet search has initially been a strong driving force for the rapid emergence of 3D building models of large urban areas. Additionally, many commercial and governmental initiatives have been started to develop urban 3D geographic information systems in a transition from the classical 2D- to the novel 3D-GIS. The modeling of building roofs is thus a relevant research topic. The focus has been on the use of aerial LiDAR point clouds (Light Detection And Ranging). However, recent progress in digital aerial cameras has rendered possible the acquisition of very dense point clouds from high overlap digital aerial imagery, and to use these point clouds jointly with the image information to generate 3D building models. This paper presents a multi-step processing framework and work flow for the automatic segmentation of building roofs in densely built-up areas from high-resolution vertical aerial images. Details extruding from, or intruding into, a roof are being excluded so that each roof is being modeled by means of its planar segments and can then be classified as a specific roof type from a set of standard roof shapes. Our experimental work employs a test area in Graz (Austria) with 186 buildings. © 2011 ACM.

关键词： Roofs

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RANSAC-based Training Data Selection for speaker state recognition

RANSAC-based Training Data Selection for speaker state recog...

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12th Annual Conference of the International Speech Communication Association, INTERSPEECH 2011

作者： Bozkurt, Elif Erzin, Engin Erdem, Çiǧdem Eroǧlu Erdem, A.Tanju Multimedia Vision and Graphics Laboratory Koç University Istanbul Turkey Department of Electrical and Electronics Engineering Bahçeşehir University Istanbul Turkey Department of Electrical and Computer Engineering Özyeǧin University Istanbul Turkey

We present a Random Sampling Consensus (RANSAC) based training approach for the problem of speaker state recognition from spontaneous speech. Our system is trained and tested with the INTERSPEECH 2011 Speaker State Challenge corpora that includes the Intoxication and the Sleepiness Sub-challenges, where each sub-challenge defines a two-class classification task. We aim to perform a RANSAC-based training data selection coupled with the Support Vector Machine (SVM) based classification to prune possible outliers, which exist in the training data. Our experimental evaluations indicate that utilization of RANSAC-based training data selection provides 66.32 % and 65.38 % unweighted average (UA) recall rate on the development and test sets for the Sleepiness Sub-challenge, respectively and a slight improvement on the Intoxication Sub-challenge performance. Copyright © 2011 ISCA.

关键词： Support vector machines

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3D roof details by 3D aerial vision

3D roof details by 3D aerial vision

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International Conference on computer vision Workshops (ICCV Workshops)

作者： Philipp Meixner Franz Leberl Mathieu Brédif Institute for Computer Graphics and Vision Graz University of Technology Austria MATIS Laboratory IGN Paris France

Virtual cities in a 3D GIS will not be complete without the details of roofs with chimneys, dormer windows, skylights. We contribute a method of extracting such details from digital large format aerial photography. The dense point clouds produced by a photogrammetric process produce major and minor plane surfaces of a roof and enter into a classification of its superstructures. In real city data with a total of 1312 superstructures the proposed automated process finds 1024, thus achieving success at a rate of 78%.

关键词： Buildings Three dimensional displays Image edge detection Cities and towns Smoothing methods Geographic Information Systems Photography

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Partial generalized correlation for hyperspectral data

Partial generalized correlation for hyperspectral data

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IEEE Symposium on Computational Intelligence and Data Mining (CIDM)

作者： Marc Strickert Björn Labitzke Volker Blanz Institute of Vision and Graphics University of Siegen Germany Computer Graphics Group University of Siegen Germany Media Systems Laboratory University of Siegen Germany

A variational approach is proposed for the unsupervised assessment of attribute variability of high-dimensional data given a differentiable similarity measure. The key question addressed is how much each data attribute contributes to an optimum transformation of vectors for reaching maximum similarity. This question is formalized and solved in a mathematically rigorous optimization framework for each data pair of interest. Trivially, for the Euclidean metric minimization to zero distance induces highest vector similarity, but in case of the linear Pearson correlation measure the highest similarity of one is desired. During optimization the not necessarily symmetric trajectories between two vectors are recorded and analyzed in terms of attribute changes and line integral. The proposed formalism allows to assess partial covariance and correlation characteristics of data attributes for vectors being compared by any differentiable similarity measure. Its potential for generating alternative and localized views such as for contrast enhancement is demonstrated for hyperspectral images from the remote sensing domain.

关键词： Correlation Euclidean distance Covariance matrix Vectors Equations Mathematical model Geologic measurements

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