1,721,061 research outputs found
Speckle Noise Reduction and Edge Enhancement in Ultrasound Images Based on Wavelet Transform
No full textFor B-mode ultrasound images, we propose an image enhancement algorithm based on a multi-resolution approach, which consists of edge enhancing and noise reducing procedures. Edge enhancement processing is applied sequentially to coarse-to-fine resolution images obtained from wavelet-transformed data. In each resolution, the structural features of each pixel are examined through eigen analysis. Then, if a pixel belongs to an edge region, we perform two-step filtering: that is, directional smoothing is conducted along the tangential direction of the edge to improve continuity and directional sharpening is conducted along the normal direction to enhance the contrast. In addition, speckle noise is alleviated by proper attenuation of the wavelet coefficients of the homogeneous regions at each band. This region-based speckle-reduction scheme is differentiated from other methods that are based on the magnitude statistics of the wavelet coefficients. The proposed algorithm enhances edges regardless of changes in the resolution of an image, and the algorithm efficiently reduces speckle noise without affecting the sharpness of the edge. Hence, compared with existing algorithms, the proposed algorithm considerably improves the subjective image quality without providing any noticeable artifacts
경사 기반의 통계적 정보를 이용한 강인한 다중센서 영상 정합
No full text학위논문(박사) - 한국과학기술원 : 전기 및 전자공학과, 2011.2, [ vii, 106 p. ]This thesis deals with the robust registration algorithm based on a new similarity measure for aligning multi-sensor images such as charged-couple device (CCD) and infrared (IR) images. Multi-sensor image registration is essential to many applications such as surveillance, remote sensing, and medical imaging. Due to different sensor characteristics and/or different sensor pose in the system, there exist geometrically relative motions such as translation, rotation, scale, and any other transformations between two sensor images. Therefore, the registration can be defined as a process to establish the spatial correspondence between two images. In this thesis, we aim to design a robust similarity measure for registering multi-sensor images to compensate such relative motions which are confined to a global projective model.
As a similarity measure for registration, mutual information (MI) based measures have been widely used for medical imaging. These MI-based methods work properly only if the intensity mapping relationship between the two images is global. However, the intensity mapping relationship is often locally different in many other multi-modal images such as ordinary CCD and IR images which are used for surveillance and remote sensing applications. Therefore, MI-based methods cannot cover such various image modalities and their registration performances are limited. Hence, to improve the registration performance, we propose a new similarity measure based on gradient-based statistical information.
For robust registration, the proposed similarity measure is based on the entropy obtained from a 3-D joint histogram incorporating edginess and generalized gradient vector flow (GGVF) information. In the measure, in order to make a reliable mapping relationship between the edge regions of two images, the concept of edginess which is normalized version of gradient magnitude is adopted so that registration performance may be affected mainly by edge existences rather ...한국과학기술원 : 전기 및 전자공학과
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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