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Author
Oriol Ramos Terrades; Ernest Valveny
Title
A new use of the ridgelets transform for describing linear singularities in images
Type
Journal Article
Year
2006
Publication
Pattern Recognition Letters
Abbreviated Journal
PRL
Volume
27
Issue
6
Pages
587–596
Keywords
Abstract
Address
Corporate Author
Thesis
Publisher
Place of Publication
Editor
Language
Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
ISBN
Medium
Area
Expedition
Conference
Notes
DAG
Approved
no
Call Number
DAG @ dag @ RaV2006a
Serial
635
Permanent link to this record
Author
Anjan Dutta; Josep Llados; Horst Bunke; Umapada Pal
Title
Product graph-based higher order contextual similarities for inexact subgraph matching
Type
Journal Article
Year
2018
Publication
Pattern Recognition
Abbreviated Journal
PR
Volume
76
Issue
Pages
596-611
Keywords
Abstract
Many algorithms formulate graph matching as an optimization of an objective function of pairwise quantification of nodes and edges of two graphs to be matched. Pairwise measurements usually consider local attributes but disregard contextual information involved in graph structures. We address this issue by proposing contextual similarities between pairs of nodes. This is done by considering the tensor product graph (TPG) of two graphs to be matched, where each node is an ordered pair of nodes of the operand graphs. Contextual similarities between a pair of nodes are computed by accumulating weighted walks (normalized pairwise similarities) terminating at the corresponding paired node in TPG. Once the contextual similarities are obtained, we formulate subgraph matching as a node and edge selection problem in TPG. We use contextual similarities to construct an objective function and optimize it with a linear programming approach. Since random walk formulation through TPG takes into account higher order information, it is not a surprise that we obtain more reliable similarities and better discrimination among the nodes and edges. Experimental results shown on synthetic as well as real benchmarks illustrate that higher order contextual similarities increase discriminating power and allow one to find approximate solutions to the subgraph matching problem.
Address
Corporate Author
Thesis
Publisher
Place of Publication
Editor
Language
Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
ISBN
Medium
Area
Expedition
Conference
Notes
DAG; 602.167; 600.097; 600.121
Approved
no
Call Number
Admin @ si @ DLB2018
Serial
3083
Permanent link to this record
Author
Sophie Wuerger; Kaida Xiao; Chenyang Fu; Dimosthenis Karatzas
Title
Colour-opponent mechanisms are not affected by age-related chromatic sensitivity changes
Type
Journal Article
Year
2010
Publication
Ophthalmic and Physiological Optics
Abbreviated Journal
OPO
Volume
30
Issue
5
Pages
635-659
Keywords
Abstract
The purpose of this study was to assess whether age-related chromatic sensitivity changes are associated with corresponding changes in hue perception in a large sample of colour-normal observers over a wide age range (n = 185; age range: 18-75 years). In these observers we determined both the sensitivity along the protan, deutan and tritan line; and settings for the four unique hues, from which the characteristics of the higher-order colour mechanisms can be derived. We found a significant decrease in chromatic sensitivity due to ageing, in particular along the tritan line. From the unique hue settings we derived the cone weightings associated with the colour mechanisms that are at equilibrium for the four unique hues. We found that the relative cone weightings (w(L) /w(M) and w(L) /w(S)) associated with the unique hues were independent of age. Our results are consistent with previous findings that the unique hues are rather constant with age while chromatic sensitivity declines. They also provide evidence in favour of the hypothesis that higher-order colour mechanisms are equipped with flexible cone weightings, as opposed to fixed weights. The mechanism underlying this compensation is still poorly understood.
Address
Corporate Author
Thesis
Publisher
Place of Publication
Editor
Language
Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
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Medium
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Notes
DAG; IF: 1.259
Approved
no
Call Number
Admin @ si @ WXF2010
Serial
1826
Permanent link to this record
Author
Jose Antonio Rodriguez; Florent Perronnin; Gemma Sanchez; Josep Llados
Title
Unsupervised writer adaptation of whole-word HMMs with application to word-spotting
Type
Journal Article
Year
2010
Publication
Pattern Recognition Letters
Abbreviated Journal
PRL
Volume
31
Issue
8
Pages
742–749
Keywords
Word-spotting; Handwriting recognition; Writer adaptation; Hidden Markov model; Document analysis
Abstract
In this paper we propose a novel approach for writer adaptation in a handwritten word-spotting task. The method exploits the fact that the semi-continuous hidden Markov model separates the word model parameters into (i) a codebook of shapes and (ii) a set of word-specific parameters.
Our main contribution is to employ this property to derive writer-specific word models by statistically adapting an initial universal codebook to each document. This process is unsupervised and does not even require the appearance of the keyword(s) in the searched document. Experimental results show an increase in performance when this adaptation technique is applied. To the best of our knowledge, this is the first work dealing with adaptation for word-spotting. The preliminary version of this paper obtained an IBM Best Student Paper Award at the 19th International Conference on Pattern Recognition.
Address
Corporate Author
Thesis
Publisher
Elsevier
Place of Publication
Editor
Language
Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
ISBN
Medium
Area
Expedition
Conference
Notes
DAG
Approved
no
Call Number
DAG @ dag @ RPS2010
Serial
1290
Permanent link to this record
Author
Anjan Dutta; Josep Llados; Umapada Pal
Title
A symbol spotting approach in graphical documents by hashing serialized graphs
Type
Journal Article
Year
2013
Publication
Pattern Recognition
Abbreviated Journal
PR
Volume
46
Issue
3
Pages
752-768
Keywords
Symbol spotting; Graphics recognition; Graph matching; Graph serialization; Graph factorization; Graph paths; Hashing
Abstract
In this paper we propose a symbol spotting technique in graphical documents. Graphs are used to represent the documents and a (sub)graph matching technique is used to detect the symbols in them. We propose a graph serialization to reduce the usual computational complexity of graph matching. Serialization of graphs is performed by computing acyclic graph paths between each pair of connected nodes. Graph paths are one-dimensional structures of graphs which are less expensive in terms of computation. At the same time they enable robust localization even in the presence of noise and distortion. Indexing in large graph databases involves a computational burden as well. We propose a graph factorization approach to tackle this problem. Factorization is intended to create a unified indexed structure over the database of graphical documents. Once graph paths are extracted, the entire database of graphical documents is indexed in hash tables by locality sensitive hashing (LSH) of shape descriptors of the paths. The hashing data structure aims to execute an approximate k-NN search in a sub-linear time. We have performed detailed experiments with various datasets of line drawings and compared our method with the state-of-the-art works. The results demonstrate the effectiveness and efficiency of our technique.
Address
Corporate Author
Thesis
Publisher
Elsevier
Place of Publication
Editor
Language
Summary Language
Original Title
Series Editor
Series Title
Abbreviated Series Title
Series Volume
Series Issue
Edition
ISSN
0031-3203
ISBN
Medium
Area
Expedition
Conference
Notes
DAG; 600.042; 600.045; 605.203; 601.152
Approved
no
Call Number
Admin @ si @ DLP2012
Serial
2127
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