José Luis Alba Castro - Profile on Academia.edu (original) (raw)

Papers by José Luis Alba Castro

Sensors

Facial motion analysis is a research field with many practical applications, and has been strongl... more Facial motion analysis is a research field with many practical applications, and has been strongly developed in the last years. However, most effort has been focused on the recognition of basic facial expressions of emotion and neglects the analysis of facial motions related to non-verbal communication signals. This paper focuses on the classification of facial expressions that are of the utmost importance in sign languages (Grammatical Facial Expressions) but also present in expressive spoken language. We have collected a dataset of Spanish Sign Language sentences and extracted the intervals for three types of Grammatical Facial Expressions: negation, closed queries and open queries. A study of several deep learning models using different input features on the collected dataset (LSE_GFE) and an external dataset (BUHMAP) shows that GFEs can be learned reliably with Graph Convolutional Networks simply fed with face landmarks.

This paper presents LSE_UVIGO, a multi-source database designed to foster research on Sign Langua... more This paper presents LSE_UVIGO, a multi-source database designed to foster research on Sign Language Recognition. It is being recorded and compiled for Spanish Sign Language (LSE acronym in Spanish) and contains also spoken Galician language, so it is very well fitted to research on these languages, but also quite useful for fundamental research in any other sign language. LSE_UVIGO is composed of two datasets: LSE_Lex40_UVIGO, a multi-sensor and multi-signer dataset acquired from scratch, designed as an incremental dataset, both in complexity of the visual content and in the variety of signers. It contains static and co-articulated sign recordings, fingerspelled and gloss-based isolated words, and sentences. Its acquisition is done in a controlled lab environment in order to obtain good quality videos with sharp video frames and RGB and depth information, making them suitable to try different approaches to automatic recognition. The second subset, LSE_TVGWeather_UVIGO is being popul...

CORILSE is a computerized corpus of Spanish Sign Language (Lengua de Signos Espanola, LSE). It co... more CORILSE is a computerized corpus of Spanish Sign Language (Lengua de Signos Espanola, LSE). It consists of a set of recordings from different discourse genres by Galician signers living in the city of Vigo. In this paper we describe its annotation system, developed on the basis of pre-existing ones (mostly the model of Auslan corpus). This includes primary annotation of id-glosses for manual signs, annotation of non-manual component, and secondary annotation of grammatical categories and relations, because this corpus is been built for grammatical analysis, in particular argument structures in LSE. Up until this moment the annotation has been basically made by hand, which is a slow and time-consuming task. The need to facilitate this process leads us to engage in the development of automatic or semi-automatic tools for manual and facial recognition. Finally, we also present the web repository that will make the corpus available to different types of users, and will allow its exploit...

arXiv: Computer Vision and Pattern Recognition, 2015

Boosting algorithms have been widely used to tackle a plethora of problems. In the last few years... more Boosting algorithms have been widely used to tackle a plethora of problems. In the last few years, a lot of approaches have been proposed to provide standard AdaBoost with cost-sensitive capabilities, each with a different focus. However, for the researcher, these algorithms shape a tangled set with diffuse differences and properties, lacking a unifying analysis to jointly compare, classify, evaluate and discuss those approaches on a common basis. In this series of two papers we aim to revisit the various proposals, both from theoretical (Part I) and practical (Part II) perspectives, in order to analyze their specific properties and behavior, with the final goal of identifying the algorithm providing the best and soundest results.

2019 International Conference on Biometrics (ICB), 2019

Over the past few years, Presentation Attack Detection (PAD) has become a fundamental part of fac... more Over the past few years, Presentation Attack Detection (PAD) has become a fundamental part of facial recognition systems. Although much effort has been devoted to anti-spoofing research, generalization in real scenarios remains a challenge. In this paper we present a new opensource evaluation framework to study the generalization capacity of face PAD methods, coined here as face-GPAD. This framework facilitates the creation of new protocols focused on the generalization problem establishing fair procedures of evaluation and comparison between PAD solutions. We also introduce a large aggregated and categorized dataset to address the problem of incompatibility between publicly available datasets. Finally, we propose a benchmark adding two novel evaluation protocols: one for measuring the effect introduced by the variations in face resolution, and the second for evaluating the influence of adversarial operating conditions.

Hesperia: Anuario de Filología Hispánica, 2020

Automatic sign language recognition (ASLR) is quite a complex task, not only for the difficulty o... more Automatic sign language recognition (ASLR) is quite a complex task, not only for the difficulty of dealing with very dynamic video information, but also because almost every sign language (SL) can be considered as an under-resourced language when it comes to language technology. Spanish sign language (LSE) is one of those under-resourced languages. Developing technology for SSL implies a number of technical challenges that must be tackled down in a structured and sequential manner. In this paper, some problems of machine-learning- based ASLR are addressed. A review of publicly available datasets is given and a new one is presented. It is also discussed the current annotations methods and annotation programs. In our review of existing datasets, our main conclusion is that there is a need for more with high-quality data and annotations.

IberSPEECH 2018, 2018

This paper explains in detail the Audiovisual system deployed by the Multimedia Technologies Grou... more This paper explains in detail the Audiovisual system deployed by the Multimedia Technologies Group (GTM) of the atlanTTic research center at the University of Vigo, for the Albayzin Multimodal Diarization Challenge (MDC) organized in the Iberspeech 2018 conference. This system is characterized by the use of state of the art face and speaker verification embeddings trained with publicly available Deep Neural Networks. Video and audio tracks are processed separately to obtain a matrix of confidence values of each time segment that are finally fused to make joint decisions on the speaker diarization result.

Proceedings of the 7th International Workshop on Pattern Recognition in Information Systems, 2007

In the context of pose robust face recognition, some approaches in the literature aim to correct ... more In the context of pose robust face recognition, some approaches in the literature aim to correct the original faces by synthesizing virtual images facing a standard pose (e.g. a frontal view), which are then fed into the recognition system. One way to do this is by warping the incoming face onto the average frontal shape of a training dataset, bearing in mind that discriminative information for classification may have been thrown away during the warping process, specially if the incoming face shape differs enough from the average shape. Recently, it has been proposed a method for generating synthetic frontal images by modification of a subset of parameters from a Point Distribution Model (the so-called pose parameters), and texture mapping. We demonstrate that if only pose parameters are modified, client specific information remains in the warped image and discrimination between subjects is more reliable. Statistical analysis of the verification experiments conducted on the XM2VTS database confirm the benefits of modifying only the pose parameters over warping onto a mean shape.

SPIE Proceedings, 2008

Beside the optimization of biometric error rates the overall security system performance in respe... more Beside the optimization of biometric error rates the overall security system performance in respect to intentional security attacks plays an important role for biometric enabled authentication schemes. As traditionally most user authentication schemes are knowledge and/or possession based, firstly in this paper we present a methodology for a security analysis of Internet-based biometric authentication systems by enhancing known methodologies such as the CERT attack-taxonomy with a more detailed view on the OSI-Model. Secondly as proof of concept, the guidelines extracted from this methodology are strictly applied to an open source Internet-based biometric authentication system (BioWebAuth). As case studies, two exemplary attacks, based on the found security leaks, are investigated and the attack performance is presented to show that during the biometric authentication schemes beside biometric error performance tuning also security issues need to be addressed. Finally, some design recommendations are given in order to ensure a minimum security level.

Face Video Competition at ICB2009

Annales Des Télécommunications, 2009

Person recognition using facial features, e.g., mug-shot images, has long been used in identity d... more Person recognition using facial features, e.g., mug-shot images, has long been used in identity documents. However, due to the widespread use of web-cams and mobile devices embedded with a camera, it is now possible to realise facial video recognition, rather than resorting to just still images. In fact, facial video recognition offers many advantages over still image recognition; these include

2008 19th International Conference on Pattern Recognition, 2008

It has been shown in many different contexts that the Generalized Gaussian (GG) distribution repr... more It has been shown in many different contexts that the Generalized Gaussian (GG) distribution represents a flexible and suitable tool for data modeling. Almost all the reported applications are focused on modeling points (fixed length vectors); a different but crucial scenario, where the employment of the GG has received little attention, is the modeling of sequential data, i.e. variable length vectors. This paper explores this last direction, describing a variant of the well known Hidden Markov Model (HMM) where the emission probability function of each state is represented by a GG. A training strategy based on the Expectation Maximization (E-M) algorithm is presented. Different experiments using both synthetic and real data (EEG signal classification and face recognition) show the suitability of the proposed approach compared with the standard Gaussian HMM.

Procedings of the British Machine Vision Conference 2013, 2013

Parameterized Appearance Models, such as Active Appearance Models (AAM), Morphable Models, or Boo... more Parameterized Appearance Models, such as Active Appearance Models (AAM), Morphable Models, or Boosted Appearance Models, have been extensively used for face alignment. Discriminative methods learn a mapping function between appearance features and shape parameters. Different mapping functions have been studied in the literature, including linear regression, which has proved to perform well when close to the true solution. Despite its easiness, it still suffers from two major drawbacks: 1) It takes the whole data without highlighting relations among different regions of the face, and 2) it is computationally expensive both in time and memory. In this paper, we analyze the covariance of the training data, and propose a way to find related information. By clustering those patches that are related, we reach a noise-reduced regression matrix. Then, we construct a clean mapping matrix, with reduced dimensionality, taking only the relevant training information. Experiments show that this method outperforms linear regression for face alignment.

Lecture Notes in Computer Science

This paper addresses the problem of biometric audiovisual person authentication in realistic acqu... more This paper addresses the problem of biometric audiovisual person authentication in realistic acquisition conditions. Differences in environmental factors or acquisition devices between enrollment and test conditions modify the verification scores distribution and degrade verification performance if not taken into account. A theoretical framework that incorporates quality measures to biometric authentication is introduced. As a result, the necessary and sufficient condition that a quality measure must hold to enable improved verification performance is given. Two quality-based score normalization techniques are derived that successfully incorporate quality factors in the verification decision process. Experiments on the multimodal BANCA database for video-based face verification and speaker verification show a statistically significant verification performance improvement when using the proposed quality-based score normalization techniques.

Gaussian mixtures versus MLP for terrain classification in Landsat TM images

ABSTRACT

Signal Processing, 1999

In this paper a method to automatically generate a Gaussian mixture classifier is presented. The ... more In this paper a method to automatically generate a Gaussian mixture classifier is presented. The growing process is based on the iterative addition of Gaussian nodes. Each iteration takes place in two sequential steps: first, using the EM algorithm, we maximize the likelihood of the data under the current configuration of the classifier; then, a new Gaussian node is added

Guide to Biometric …, 2009

An overview of selected topics in face recognition is first presented in this chapter. The BioSec... more An overview of selected topics in face recognition is first presented in this chapter. The BioSecure 2D-face Benchmarking Framework is also described, com-posed of open-source software, publicly available databases and protocols. Three methods for 2D-face ...

Desarrollo de Soluciones Cliente-Servidor para la Verificación Biométrica de Identidad y Monitorización en Plataformas Web: Aplicación a Tele-enseñanza

... y en un principio exigían la necesidad de que los educadores tuvieran bastante conocimiento t... more ... y en un principio exigían la necesidad de que los educadores tuvieran bastante conocimiento técnico para su uso efectivo ... No obstante, estos problemas están en vías de solución, ya que cada vez aparecen nuevas versiones de los LMS, tanto comerciales como de software ...

Biometrics for Web Authentication: an Open Source Java-Based Approach

... Automatic identity ver-ification, based on distinctive anatomical features (eg, face, voice, ... more ... Automatic identity ver-ification, based on distinctive anatomical features (eg, face, voice, fingerprint, iris, etc.) and behavioral characteristics (eg, online/offline signature, keystroke dynamics, etc), is becoming an increasingly ... Biometrics for Web Authentication: an Open ...

I Intelligence Everywhere-Intelligent Techniques for Biometric Based Authentication-An Open Source Java Framework for Biometric Web Authentication Based on BioAPI

In this paper we propose a solution to obtain useful and reliable student session logs in a Learn... more In this paper we propose a solution to obtain useful and reliable student session logs in a Learning Management System (LMS) combining current logs with biometrics-based logs that show the student behaviour during the whole learning session. The aims of our solution are to guarantee that the online student is who he/she claims to be, and also to know exactly how much time he/she spends in front of the computer reading each LMS content. Even when the proposed solution does not completely avoid cheating, the use of biometric data during authentication and face tracking provides additional help to validate student performance during learning sessions. In this way it is possible to improve security for specific contents, to gain feedback of the student effort and to check the actual time spent in learning.