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Author Agata Lapedriza; David Masip; Jordi Vitria
Title (down) On the Use of External Face Features for Identity Verification Type Journal
Year 2006 Publication Journal of Multimedia, 1(4): 11–20 Abbreviated Journal
Volume 1 Issue 4 Pages 11-20
Keywords Face Verification, Computer Vision, Machine Learning
Abstract In general automatic face classification applications images are captured in natural environments. In these cases, the performance is affected by variations in facial images related to illumination, pose, occlusion or expressions. Most of the existing face classification systems use only the internal features information, composed by eyes, nose and mouth, since they are more difficult to imitate. Nevertheless, nowadays a lot of applications not related to security are developed, and in these cases the information located at head, chin or ears zones (external features) can be useful to improve the current accuracies. However, the lack of a natural alignment in these areas makes difficult to extract these features applying classic Bottom-Up methods. In this paper, we propose a complete scheme based on a Top-Down reconstruction algorithm to extract external features of face images. To test our system we have performed face verification experiments using public databases, given that identity verification is a general task that has many real life applications. We have considered images uniformly illuminated, images with occlusions and images with high local changes in the illumination, and the obtained results show that the information contributed by the external features can be useful for verification purposes, specially significant when faces are partially occluded.
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Notes OR;MV Approved no
Call Number BCNPCL @ bcnpcl @ LMV2006b Serial 708
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Author Alex Gomez-Villa; Adrian Martin; Javier Vazquez; Marcelo Bertalmio; Jesus Malo
Title (down) On the synthesis of visual illusions using deep generative models Type Journal Article
Year 2022 Publication Journal of Vision Abbreviated Journal JOV
Volume 22(8) Issue 2 Pages 1-18
Keywords
Abstract Visual illusions expand our understanding of the visual system by imposing constraints in the models in two different ways: i) visual illusions for humans should induce equivalent illusions in the model, and ii) illusions synthesized from the model should be compelling for human viewers too. These constraints are alternative strategies to find good vision models. Following the first research strategy, recent studies have shown that artificial neural network architectures also have human-like illusory percepts when stimulated with classical hand-crafted stimuli designed to fool humans. In this work we focus on the second (less explored) strategy: we propose a framework to synthesize new visual illusions using the optimization abilities of current automatic differentiation techniques. The proposed framework can be used with classical vision models as well as with more recent artificial neural network architectures. This framework, validated by psychophysical experiments, can be used to study the difference between a vision model and the actual human perception and to optimize the vision model to decrease this difference.
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Notes LAMP; 600.161; 611.007 Approved no
Call Number Admin @ si @ GMV2022 Serial 3682
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Author A. Pujol; Alex Caralps; Juan J. Villanueva
Title (down) On the suitability of pixel-outlier removal in face recognition. Type Miscellaneous
Year 2001 Publication Proceedings of the IX Spanish Symposium on Pattern Recognition and Image Analysis, 1:241–247 Abbreviated Journal
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Notes Approved no
Call Number ISE @ ise @ PCV2001 Serial 152
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Author Petia Radeva
Title (down) On the Role of Intravascular Ultrasound Image Analysis Type Miscellaneous
Year 2003 Publication Angiography and Plaque Imaging: Advanced Segmentation Techniques, CRC, pp.397–450, ISBN: 0849317401 Abbreviated Journal
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Notes MILAB Approved no
Call Number BCNPCL @ bcnpcl @ Rad2003 Serial 402
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Author Alejandro Cartas; Estefania Talavera; Petia Radeva; Mariella Dimiccoli
Title (down) On the Role of Event Boundaries in Egocentric Activity Recognition from Photostreams Type Miscellaneous
Year 2018 Publication Arxiv Abbreviated Journal
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Abstract Event boundaries play a crucial role as a pre-processing step for detection, localization, and recognition tasks of human activities in videos. Typically, although their intrinsic subjectiveness, temporal bounds are provided manually as input for training action recognition algorithms. However, their role for activity recognition in the domain of egocentric photostreams has been so far neglected. In this paper, we provide insights of how automatically computed boundaries can impact activity recognition results in the emerging domain of egocentric photostreams. Furthermore, we collected a new annotated dataset acquired by 15 people by a wearable photo-camera and we used it to show the generalization capabilities of several deep learning based architectures to unseen users.
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Notes MILAB; no proj Approved no
Call Number Admin @ si @ CTR2018 Serial 3184
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Author Miquel Ferrer; F. Serratosa; Ernest Valveny
Title (down) On the Relation Between the Median Graph and the Maximum Common Subgraph of a Set of Graphs Type Book Chapter
Year 2007 Publication Abbreviated Journal
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Address Alicante (Spain)
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Notes DAG Approved no
Call Number DAG @ dag @ FSV2007 Serial 790
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Author David Masip; Jordi Vitria
Title (down) On the Nearest Neighbor Approach for Gender Recognition Type Miscellaneous
Year 2003 Publication In I. Aguilo, Ll. Valverde M.T. Escrig, editors. Artificial Intelligence Research and Development. IOS PRESS pp.178–188 Abbreviated Journal
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Address Amsterdam
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Notes OR;MV Approved no
Call Number BCNPCL @ bcnpcl @ MaV2003b Serial 387
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Author David Masip; Jordi Vitria
Title (down) On the Nearest Neighbor Approach for Gender Recognition Type Miscellaneous
Year 2003 Publication 6th Catalonian Conference on Artificial Intelligence Abbreviated Journal
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Address Palma de Mallorca
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Notes OR;MV Approved no
Call Number BCNPCL @ bcnpcl @ MaV2003c Serial 392
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Author Debora Gil; Jose Maria-Carazo; Roberto Marabini
Title (down) On the nature of 2D crystal unbending Type Journal Article
Year 2006 Publication Journal of Structural Biology Abbreviated Journal
Volume 156 Issue 3 Pages 546-555
Keywords Electron microscopy
Abstract Crystal unbending, the process that aims to recover a perfect crystal from experimental data, is one of the more important steps in electron crystallography image processing. The unbending process involves three steps: estimation of the unit cell displacements from their ideal positions, extension of the deformation field to the whole image and transformation of the image in order to recover an ideal crystal. In this work, we present a systematic analysis of the second step oriented to address two issues. First, whether the unit cells remain undistorted and only the distance between them should be changed (rigid case) or should be modified with the same deformation suffered by the whole crystal (elastic case). Second, the performance of different extension algorithms (interpolation versus approximation) is explored. Our experiments show that there is no difference between elastic and rigid cases or among the extension algorithms. This implies that the deformation fields are constant over large areas. Furthermore, our results indicate that the main source of error is the transformation of the crystal image.
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ISSN 1047-8477 ISBN Medium
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Notes IAM; Approved no
Call Number IAM @ iam @ GCM2006 Serial 1519
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Author Akhil Gurram; Antonio Lopez
Title (down) On the Metrics for Evaluating Monocular Depth Estimation Type Miscellaneous
Year 2023 Publication Arxiv Abbreviated Journal
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Abstract Monocular Depth Estimation (MDE) is performed to produce 3D information that can be used in downstream tasks such as those related to on-board perception for Autonomous Vehicles (AVs) or driver assistance. Therefore, a relevant arising question is whether the standard metrics for MDE assessment are a good indicator of the accuracy of future MDE-based driving-related perception tasks. We address this question in this paper. In particular, we take the task of 3D object detection on point clouds as a proxy of on-board perception. We train and test state-of-the-art 3D object detectors using 3D point clouds coming from MDE models. We confront the ranking of object detection results with the ranking given by the depth estimation metrics of the MDE models. We conclude that, indeed, MDE evaluation metrics give rise to a ranking of methods that reflects relatively well the 3D object detection results we may expect. Among the different metrics, the absolute relative (abs-rel) error seems to be the best for that purpose.
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Notes ADAS Approved no
Call Number Admin @ si @ GuL2023 Serial 3867
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Author Mohammed Al Rawi; Dimosthenis Karatzas
Title (down) On the Labeling Correctness in Computer Vision Datasets Type Conference Article
Year 2018 Publication Proceedings of the Workshop on Interactive Adaptive Learning, co-located with European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases Abbreviated Journal
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Abstract Image datasets have heavily been used to build computer vision systems.
These datasets are either manually or automatically labeled, which is a
problem as both labeling methods are prone to errors. To investigate this problem, we use a majority voting ensemble that combines the results from several Convolutional Neural Networks (CNNs). Majority voting ensembles not only enhance the overall performance, but can also be used to estimate the confidence level of each sample. We also examined Softmax as another form to estimate posterior probability. We have designed various experiments with a range of different ensembles built from one or different, or temporal/snapshot CNNs, which have been trained multiple times stochastically. We analyzed CIFAR10, CIFAR100, EMNIST, and SVHN datasets and we found quite a few incorrect
labels, both in the training and testing sets. We also present detailed confidence analysis on these datasets and we found that the ensemble is better than the Softmax when used estimate the per-sample confidence. This work thus proposes an approach that can be used to scrutinize and verify the labeling of computer vision datasets, which can later be applied to weakly/semi-supervised learning. We propose a measure, based on the Odds-Ratio, to quantify how many of these incorrectly classified labels are actually incorrectly labeled and how many of these are confusing. The proposed methods are easily scalable to larger datasets, like ImageNet, LSUN and SUN, as each CNN instance is trained for 60 epochs; or even faster, by implementing a temporal (snapshot) ensemble.
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Area Expedition Conference ECML-PKDDW
Notes DAG; 600.121; 600.129 Approved no
Call Number Admin @ si @ RaK2018 Serial 3144
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Author Pau Torras; Arnau Baro; Lei Kang; Alicia Fornes
Title (down) On the Integration of Language Models into Sequence to Sequence Architectures for Handwritten Music Recognition Type Conference Article
Year 2021 Publication International Society for Music Information Retrieval Conference Abbreviated Journal
Volume Issue Pages 690-696
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Abstract Despite the latest advances in Deep Learning, the recognition of handwritten music scores is still a challenging endeavour. Even though the recent Sequence to Sequence(Seq2Seq) architectures have demonstrated its capacity to reliably recognise handwritten text, their performance is still far from satisfactory when applied to historical handwritten scores. Indeed, the ambiguous nature of handwriting, the non-standard musical notation employed by composers of the time and the decaying state of old paper make these scores remarkably difficult to read, sometimes even by trained humans. Thus, in this work we explore the incorporation of language models into a Seq2Seq-based architecture to try to improve transcriptions where the aforementioned unclear writing produces statistically unsound mistakes, which as far as we know, has never been attempted for this field of research on this architecture. After studying various Language Model integration techniques, the experimental evaluation on historical handwritten music scores shows a significant improvement over the state of the art, showing that this is a promising research direction for dealing with such difficult manuscripts.
Address Virtual; November 2021
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Area Expedition Conference ISMIR
Notes DAG; 600.140; 600.121 Approved no
Call Number Admin @ si @ TBK2021 Serial 3616
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Author Josep Llados; Marçal Rusiñol; Alicia Fornes; David Fernandez; Anjan Dutta
Title (down) On the Influence of Word Representations for Handwritten Word Spotting in Historical Documents Type Journal Article
Year 2012 Publication International Journal of Pattern Recognition and Artificial Intelligence Abbreviated Journal IJPRAI
Volume 26 Issue 5 Pages 1263002-126027
Keywords Handwriting recognition; word spotting; historical documents; feature representation; shape descriptors Read More: http://www.worldscientific.com/doi/abs/10.1142/S0218001412630025
Abstract 0,624 JCR
Word spotting is the process of retrieving all instances of a queried keyword from a digital library of document images. In this paper we evaluate the performance of different word descriptors to assess the advantages and disadvantages of statistical and structural models in a framework of query-by-example word spotting in historical documents. We compare four word representation models, namely sequence alignment using DTW as a baseline reference, a bag of visual words approach as statistical model, a pseudo-structural model based on a Loci features representation, and a structural approach where words are represented by graphs. The four approaches have been tested with two collections of historical data: the George Washington database and the marriage records from the Barcelona Cathedral. We experimentally demonstrate that statistical representations generally give a better performance, however it cannot be neglected that large descriptors are difficult to be implemented in a retrieval scenario where word spotting requires the indexation of data with million word images.
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Notes DAG Approved no
Call Number Admin @ si @ LRF2012 Serial 2128
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Author David Fernandez; Pau Riba; Alicia Fornes; Josep Llados
Title (down) On the Influence of Key Point Encoding for Handwritten Word Spotting Type Conference Article
Year 2014 Publication 14th International Conference on Frontiers in Handwriting Recognition Abbreviated Journal
Volume Issue Pages 476 - 481
Keywords Local descriptors; Interest points; Handwritten documents; Word spotting; Historical document analysis
Abstract In this paper we evaluate the influence of the selection of key points and the associated features in the performance of word spotting processes. In general, features can be extracted from a number of characteristic points like corners, contours, skeletons, maxima, minima, crossings, etc. A number of descriptors exist in the literature using different interest point detectors. But the intrinsic variability of handwriting vary strongly on the performance if the interest points are not stable enough. In this paper, we analyze the performance of different descriptors for local interest points. As benchmarking dataset we have used the Barcelona Marriage Database that contains handwritten records of marriages over five centuries.
Address Creete Island; Grecia; September 2014
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ISSN 2167-6445 ISBN 978-1-4799-4335-7 Medium
Area Expedition Conference ICFHR
Notes DAG; 600.056; 600.061; 602.006; 600.077 Approved no
Call Number Admin @ si @ FRF2014 Serial 2460
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Author Albin Soutif; Marc Masana; Joost Van de Weijer; Bartlomiej Twardowski
Title (down) On the importance of cross-task features for class-incremental learning Type Conference Article
Year 2021 Publication Theory and Foundation of continual learning workshop of ICML Abbreviated Journal
Volume Issue Pages
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Abstract In class-incremental learning, an agent with limited resources needs to learn a sequence of classification tasks, forming an ever growing classification problem, with the constraint of not being able to access data from previous tasks. The main difference with task-incremental learning, where a task-ID is available at inference time, is that the learner also needs to perform crosstask discrimination, i.e. distinguish between classes that have not been seen together. Approaches to tackle this problem are numerous and mostly make use of an external memory (buffer) of non-negligible size. In this paper, we ablate the learning of crosstask features and study its influence on the performance of basic replay strategies used for class-IL. We also define a new forgetting measure for class-incremental learning, and see that forgetting is not the principal cause of low performance. Our experimental results show that future algorithms for class-incremental learning should not only prevent forgetting, but also aim to improve the quality of the cross-task features. This is especially important when the number of classes per task is small.
Address Virtual; July 2021
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Area Expedition Conference ICMLW
Notes LAMP Approved no
Call Number Admin @ si @ SMW2021 Serial 3588
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