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Espinosa-Duro V.,EUP Mataro | Faundez-Zanuy M.,EUP Mataro | Mekyska J.,Brno University of Technology | Monte-Moreno E.,Polytechnic University of Catalonia
Cognitive Computation | Year: 2010

In this paper, we propose a criterion for pairwise combination of information from different sensors in order to decide how a given pair of sensors is useful for different applications. This criterion is related to the principle of maximum information preservation. We present experimental results for the case of face images at different spectral bands, which allow for the in advance evaluation of the usefulness of different sensor combinations as well as the possibility for crossed-sensor recognition (matching of images acquired in different spectral bands). The criterion that we propose is a generalization of the Fisher score for the case of mutual information, which is measured as the ratio of the interclass information to the intraclass. The score we propose measures the behavior of a pair of sensors either when they are used in combination or when they are used to discriminate between classes. Based on Information Theory measurements, we conclude that the best spectral band combination always contains the thermal image, while the best combination for crossed-sensor recognition is VIS and NIR. © 2010 Springer Science+Business Media, LLC.


Mekyska J.,DT | Espinosa-Duro V.,EUP Mataro | Faundez-Zanuy M.,EUP Mataro
Proceedings - International Carnahan Conference on Security Technology | Year: 2010

Face segmentation is a first step for face biometric systems. In this paper we present a face segmentation algorithm for thermographic images. This algorithm is compared with the classic Viola and Jones algorithm used for visible images. Experimental results reveal that, when segmenting a multispectral (visible and thermal) face database, the proposed algorithm is more than 10 times faster, while the accuracy of face segmentation in thermal images is higher than in case of Viola-Jones. ©2010 IEEE.


Faundez-Zanuy M.,EUP Mataro | Mekyska J.,Brno University of Technology | Espinosa-Duro V.,EUP Mataro
Pattern Recognition Letters | Year: 2011

In this paper we present a new thermographic image database, suitable for the analysis of automatic focusing measures. This database contains the images of 10 scenes, each of which is represented once for each of 96 different focus positions. Using this database, we evaluate the usefulness of five focus measures with the goal of determining the optimal focus position. Experimental results reveal that the accurate automatic detection of optimal focus position can be achieved with a low computational burden. We also present an acquisition tool for obtaining thermal images. To the best of our knowledge, this is the first study on the automatic focusing of thermal images. © 2011 Elsevier B.V. All rights reserved.


Espinosa-Duro V.,EUP Mataro | Faundez-Zanuy M.,EUP Mataro | Mekyska J.,Brno University of Technology
Cognitive Computation | Year: 2011

Although audio-visual human systems have several well-known limitations, artificial sensors can measure information beyond our limits. What would happen if we were able to overcome our limitations? Would we be able to obtain a better knowledge of our environment? Or the information beyond our limits is redundant? In this paper, we compare infrared, thermal and visible images from an information theory point of view. We have acquired a small database and compared several measurements over these images. While infrasounds and ultrasounds are not directly applicable, for instance, to speaker recognition due to the impossibility of human beings generating sounds in these frequencies, this is not the case with image signals beyond the visible spectrum for face recognition. We have observed that visible, near-infrared and thermal images contain a small amount of redundancy (less than 1,55 bits). © 2010 Springer Science+Business Media, LLC.


Sesa-Nogueras E.,EUP Mataro | Faundez-Zanuy M.,EUP Mataro | Mekyska J.,Brno University of Technology
Cognitive Computation | Year: 2012

This paper is aimed at analysing, from an information theory perspective, the gestures produced by human beings when handwriting a text. Modern capturing devices allow the gathering of data not only from the on-surface movements of the hand, but also from the in-air trajectories performed when the hand moves in the air from one stroke to the next. Our past research with isolated uppercase words clearly suggests that both types of trajectories have a biometric potential to perform writer recognition and that they can be effectively combined to enhance the recognition accuracy. With samples from the BiosecurID database, we have analysed the entropy of each kind of trajectories, as well as the amount of information they share, and the difference between intra- and inter-writer measures of the mutual information. The results show that when pressure is not taken into account, the amount of information is similar in both types of trajectories. Furthermore, even if they share some information, in-air and on-surface trajectories appear to be notably non-redundant. © 2011 Springer Science+Business Media, LLC.


Esposito A.,The Second University of Naples | Capuano V.,The Second University of Naples | Mekyska J.,Brno University of Technology | Faundez-Zanuy M.,EUP Mataro
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

This work defines a procedure for collecting naturally induced emotional facial expressions through the vision of movie excerpts with high emotional contents and reports experimental data ascertaining the effects of emotions on memory word recognition tasks. The induced emotional states include the four basic emotions of sadness, disgust, happiness, and surprise, as well as the neutral emotional state. The resulting database contains both thermal and visible emotional facial expressions, portrayed by forty Italian subjects and simultaneously acquired by appropriately synchronizing a thermal and a standard visible camera. Each subject's recording session lasted 45 minutes, allowing for each mode (thermal or visible) to collect a minimum of 2000 facial expressions from which a minimum of 400 were selected as highly expressive of each emotion category. The database is available to the scientific community and can be obtained contacting one of the authors. For this pilot study, it was found that emotions and/or emotion categories do not affect individual performance on memory word recognition tasks and temperature changes in the face or in some regions of it do not discriminate among emotional states. © 2012 Springer-Verlag.


Faundez-Zanuy M.,EUP Mataro | Mekyska J.,Brno University of Technology | Font-Aragones X.,EUP Mataro
Cognitive Computation | Year: 2014

In this paper, we present a new hand database called Tecnocampus Hand Image Database that includes right hand, palm and dorsal images. All the images have been acquired with three different sensors (visible, near-infrared and thermal). This database consists of 100 people acquired in five different acquisition sessions, two images per session and palm/dorsal sides. The total amount of pictures is 6.000, and it is mainly developed for hand image biometric recognition purposes. In addition, the database has been studied from the information theory point of view, and we found that this highest level of information is achieved in thermal spectrum. Furthermore, a low level of mutual information between different spectrums is also demonstrated. This opens an interesting research field in multi-sensor data fusion. © 2013 Springer Science+Business Media New York.


Espinosa-Duro V.,EUP Mataro | Faundez-Zanuy M.,EUP Mataro | Mekyska J.,Brno University of Technology
Cognitive Computation | Year: 2013

In this paper, we present a new database acquired with three different sensors (visible, near infrared and thermal) under different illumination conditions. This database consists of 41 people acquired in four different acquisition sessions, five images per session and three different illumination conditions. The total amount of pictures is 7,380 pictures. Experimental results consist of single sensor experiments as well as the combination of two and three sensors under different illumination conditions (natural, infrared and artificial illumination). We have found that the three studied spectral bands contribute in a nearly equal proportion to a combined system. Experimental results show a significant improvement combining the three spectrums, even when using a simple classifier and feature extractor. In six of the nine studied scenarios, we obtained identification rates higher or equal to 98 %, when using a trained combination rule, and two cases of nine when using a fixed rule. © 2012 Springer Science+Business Media, LLC.


Benes R.,Brno University of Technology | Dvorak P.,Brno University of Technology | Faundez-Zanuy M.,EUP Mataro | Espinosa-Duro V.,EUP Mataro | Mekyska J.,Brno University of Technology
Pattern Recognition Letters | Year: 2013

This paper proposes a novel algorithm for multi-focus thermal image fusion. The algorithm is based on local activity analysis and advanced pre-selection of images into fusion process. The algorithm improves the object temperature measurement error up to 5 °C. The proposed algorithm is evaluated by half total error rate, root mean squared error, cross correlation and visual inspection. To the best of our knowledge, this is the first work devoted to multi-focus thermal image fusion. For testing of proposed algorithm we acquire six thermal image set with objects at different focal depth. © 2012 Elsevier B.V. All rights reserved.


Faundez-Zanuy M.,EUP Mataro | Sesa-Nogueras E.,EUP Mataro | Roure-Alcobe J.,EUP Mataro
Proceedings - International Carnahan Conference on Security Technology | Year: 2012

One of the main drawbaks of biometric recognition is its unstability along time. One of the main reasons for the loss of performance of biometric systems is the aging of its enrolled users. Features-and models built from them-that were up-to-date at the time of their acquisition may eventually become outdated, leading to a failure in recognition tasks. In this paper, we analyze the effect of aging in online handwriting as well as its relevance on biometric error rates. Experimets have been conducted on our BIOSECURID database, which contains data donated by 400 individuals. According to our preliminary experiments, the average handwriting speed steeply decreases for writers who are 60 and above. Regarding the relation between verification errors and age, results suggest that false rejections are not age-dependent while false acceptances seem to be related to the age of the writer. © 2012 IEEE.

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