2014 |
Peer, Peter; Emeršič, Žiga; Bule, Jernej; Žganec-Gros, Jerneja; Štruc, Vitomir Strategies for exploiting independent cloud implementations of biometric experts in multibiometric scenarios Članek v strokovni reviji V: Mathematical problems in engineering, vol. 2014, 2014. Povzetek | Povezava | BibTeX | Oznake: application, biometrics, cloud computing, face recognition, fingerprint recognition, fusion @article{peer2014strategies,Cloud computing represents one of the fastest growing areas of technology and offers a new computing model for various applications and services. This model is particularly interesting for the area of biometric recognition, where scalability, processing power, and storage requirements are becoming a bigger and bigger issue with each new generation of recognition technology. Next to the availability of computing resources, another important aspect of cloud computing with respect to biometrics is accessibility. Since biometric cloud services are easily accessible, it is possible to combine different existing implementations and design new multibiometric services that next to almost unlimited resources also offer superior recognition performance and, consequently, ensure improved security to its client applications. Unfortunately, the literature on the best strategies of how to combine existing implementations of cloud-based biometric experts into a multibiometric service is virtually nonexistent. In this paper, we try to close this gap and evaluate different strategies for combining existing biometric experts into a multibiometric cloud service. We analyze the (fusion) strategies from different perspectives such as performance gains, training complexity, or resource consumption and present results and findings important to software developers and other researchers working in the areas of biometrics and cloud computing. The analysis is conducted based on two biometric cloud services, which are also presented in the paper. |
Štruc, Vitomir; Žganec-Gros, Jerneja; Vesnicer, Boštjan; Pavešić, Nikola Beyond parametric score normalisation in biometric verification systems Članek v strokovni reviji V: IET Biometrics, vol. 3, no. 2, str. 62–74, 2014. Povzetek | Povezava | BibTeX | Oznake: biometrics, face verification, hybrid score normalization, score normalization, t-norm, tz-norm, z-norm, zt-norm @article{struc2014beyond,Similarity scores represent the basis for identity inference in biometric verification systems. However, because of the so-called miss-matched conditions across enrollment and probe samples and identity-dependent factors these scores typically exhibit statistical variations that affect the verification performance of biometric systems. To mitigate these variations, scorenormalisation techniques, such as the z-norm, the t-norm or the zt-norm, are commonly adopted. In this study, the authors study the problem of score normalisation in the scope of biometric verification and introduce a new class of non-parametric normalisation techniques, which make no assumptions regarding the shape of the distribution from which the scores are drawn (as the parametric techniques do). Instead, they estimate the shape of the score distribution and use the estimate to map the initial distribution to a common (predefined) distribution. Based on the new class of normalisation techniques they also develop a hybrid normalisation scheme that combines non-parametric and parametric techniques into hybrid two-step procedures. They evaluate the performance of the non-parametric and hybrid techniques in face-verification experiments on the FRGCv2 and SCFace databases and show that the non-parametric techniques outperform their parametric counterparts and that the hybrid procedure is not only feasible, but also retains some desirable characteristics from both the non-parametric and the parametric techniques. |
Emeršič, Žiga; Bule, Jernej; Žganec-Gros, Jerneja; Štruc, Vitomir; Peer, Peter A case study on multi-modal biometrics in the cloud Članek v strokovni reviji V: Electrotechnical Review, vol. 81, no. 3, str. 74, 2014. Povzetek | Povezava | BibTeX | Oznake: cloud, cloud computing, face recognition, face verification, fingerprint verification, fingerprints, fusion @article{emersic2014case,Cloud computing is particularly interesting for the area of biometric recognition, where scalability, availability and accessibility are important aspects. In this paper we try to evaluate different strategies for combining existing uni-modal (cloud-based) biometric experts into a multi-biometric cloud-service. We analyze several fusion strategies from the perspective of performance gains, training complexity and resource consumption and discuss the results of our analysis. The experimental evaluation is conducted based on two biometric cloud-services developed in the scope of the Competence Centere CLASS, a face recognition service and a fingerprint recognition service, which are also briefly described in the paper. The presented results are important to researchers and developers working in the area of biometric services for the cloud looking for easy solutions for improving the quality of their services. |
Križaj, Janez; Štruc, Vitomir; Mihelič, France A Feasibility Study on the Use of Binary Keypoint Descriptors for 3D Face Recognition Proceedings Article V: Proceedings of the Mexican Conference on Pattern Recognition (MCPR), str. 142–151, Springer 2014. Povzetek | Povezava | BibTeX | Oznake: 3d face recognition, binary descriptors, biometrics, BRISK, CASIA, face verification, FREAK, FRGC, MCPR, ORB, performance evaluation, SIFT, SURF @inproceedings{krivzaj2014feasibility,Despite the progress made in the area of local image descriptors in recent years, virtually no literature is available on the use of more recent descriptors for the problem of 3D face recognition, such as BRIEF, ORB, BRISK or FREAK, which are binary in nature and, therefore, tend to be faster to compute and match, while requiring signi cantly less memory for storage than, for example, SIFT or SURF. In this paper, we try to close this gap and present a feasibility study on the use of these descriptors for 3D face recognition. Descriptors are evaluated on the three challenging 3D face image datasets, namely, the FRGC, UMB and CASIA. Our experiments show the binary descriptors ensure slightly lower veri cation rates than SIFT, comparable to those of the SURF descriptor, while being an order of magnitude faster than SIFT. The results suggest that the use of binary descriptors represents a viable alternative to the established descriptors. |
Križaj, Janez; Štruc, Vitomir; Dobrišek, Simon; Marčetić, Darijan; Ribarić, Slobodan SIFT vs. FREAK: Assessing the usefulness of two keypoint descriptors for 3D face verification Proceedings Article V: 37th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), str. 1336–1341, Mipro Opatija, Croatia, 2014. Povzetek | Povezava | BibTeX | Oznake: 3d face recognition, binary descriptors, face recognition, FREAK, performance comparison, performance evaluation, SIFT @inproceedings{krivzaj2014sift,Many techniques in the area of 3D face recognition rely on local descriptors to characterize the surface-shape information around points of interest (or keypoints) in the 3D images. Despite the fact that a lot of advancements have been made in the area of keypoint descriptors over the last years, the literature on 3D-face recognition for the most part still focuses on established descriptors, such as SIFT and SURF, and largely neglects more recent descriptors, such as the FREAK descriptor. In this paper we try to bridge this gap and assess the usefulness of the FREAK descriptor for the task for 3D face recognition. Of particular interest to us is a direct comparison of the FREAK and SIFT descriptors within a simple verification framework. To evaluate our framework with the two descriptors, we conduct 3D face recognition experiments on the challenging FRGCv2 and UMBDB databases and show that the FREAK descriptor ensures a very competitive verification performance when compared to the SIFT descriptor, but at a fraction of the computational cost. Our results indicate that the FREAK descriptor is a viable alternative to the SIFT descriptor for the problem of 3D face verification and due to its binary nature is particularly useful for real-time recognition systems and verification techniques for low-resource devices such as mobile phones, tablets and alike. |
Marčetić, Darijan; Ribarić, Slobodan; Štruc, Vitomir; Pavešić, Nikola An experimental tattoo de-identification system for privacy protection in still images Proceedings Article V: 37th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), str. 1288–1293, Mipro IEEE, 2014. Povzetek | Povezava | BibTeX | Oznake: computer vision, deidentification, MIPRO, privacy protection, tattoo deidentification @inproceedings{marcetic2014experimental,An experimental tattoo de-identification system for privacy protection in still images is described in the paper. The system consists of the following modules: skin detection, region of interest detection, feature extraction, tattoo database, matching, tattoo detection, skin swapping, and quality evaluation. Two methods for tattoo localization are presented. The first is a simple ad-hoc method based only on skin colour. The second is based on skin colour, texture and SIFT features. The appearance of each tattoo area is de-identified in such a way that its skin colour and skin texture are similar to the surrounding skin area. Experimental results for still images in which tattoo location, distance, size, illumination, and motion blur have large variability are presented. The system is subjectively evaluated based on the results of tattoo localization, the level of privacy protection and the naturalness of the de-identified still images. The level of privacy protection is estimated based on the quality of the removal of the tattoo appearance and the concealment of its location. |
Vesnicer, Boštjan; Žganec-Gros, Jerneja; Dobrišek, Simon; Štruc, Vitomir Incorporating Duration Information into I-Vector-Based Speaker-Recognition Systems Proceedings Article V: Proceedings of Odyssey: The Speaker and Language Recognition Workshop, str. 241–248, 2014. Povzetek | Povezava | BibTeX | Oznake: acustic features, biometrics, duration, duration modeling, i-vector, i-vector challenge, Odyssey, performance evaluation, speaker recognition, speech technologies @inproceedings{vesnicer2014incorporating,Most of the existing literature on i-vector-based speaker recognition focuses on recognition problems, where i-vectors are extracted from speech recordings of sufficient length. The majority of modeling/recognition techniques therefore simply ignores the fact that the i-vectors are most likely estimated unreliably when short recordings are used for their computation. Only recently, were a number of solutions proposed in the literature to address the problem of duration variability, all treating the i-vector as a random variable whose posterior distribution can be parameterized by the posterior mean and the posterior covariance. In this setting the covariance matrix serves as a measure of uncertainty that is related to the length of the available recording. In contract to these solutions, we address the problem of duration variability through weighted statistics. We demonstrate in the paper how established feature transformation techniques regularly used in the area of speaker recognition, such as PCA or WCCN, can be modified to take duration into account. We evaluate our weighting scheme in the scope of the i-vector challenge organized as part of the Odyssey, Speaker and Language Recognition Workshop 2014 and achieve a minimal DCF of 0.280, which at the time of writing puts our approach in third place among all the participating institutions. |
Beveridge, Ross; Zhang, Hao; Flynn, Patrick; Lee, Yooyoung; Liong, Venice Erin; Lu, Jiwen; de Angeloni, Marcus Assis; de Pereira, Tiago Freitas; Li, Haoxiang; Hua, Gang; Štruc, Vitomir; Križaj, Janez; Phillips, Jonathon The ijcb 2014 pasc video face and person recognition competition Proceedings Article V: Proceedings of the IEEE International Joint Conference on Biometrics (IJCB), str. 1–8, IEEE 2014. Povzetek | Povezava | BibTeX | Oznake: biometrics, competition, face recognition, group evaluation, IJCB, PaSC, performance evaluation @inproceedings{beveridge2014ijcb,The Point-and-Shoot Face Recognition Challenge (PaSC) is a performance evaluation challenge including 1401 videos of 265 people acquired with handheld cameras and depicting people engaged in activities with non-frontal head pose. This report summarizes the results from a competition using this challenge problem. In the Video-to-video Experiment a person in a query video is recognized by comparing the query video to a set of target videos. Both target and query videos are drawn from the same pool of 1401 videos. In the Still-to-video Experiment the person in a query video is to be recognized by comparing the query video to a larger target set consisting of still images. Algorithm performance is characterized by verification rate at a false accept rate of 0:01 and associated receiver operating characteristic (ROC) curves. Participants were provided eye coordinates for video frames. Results were submitted by 4 institutions: (i) Advanced Digital Science Center, Singapore; (ii) CPqD, Brasil; (iii) Stevens Institute of Technology, USA; and (iv) University of Ljubljana, Slovenia. Most competitors demonstrated video face recognition performance superior to the baseline provided with PaSC. The results represent the best performance to date on the handheld video portion of the PaSC. |
2013 |
Križaj, Janez; Dobrišek, Simon; Štruc, Vitomir; Pavešić, Nikola Robust 3D face recognition using adapted statistical models Proceedings Article V: Proceedings of the Electrotechnical and Computer Science Conference (ERK'13), 2013. Povzetek | Povezava | BibTeX | Oznake: 3d face recognition, biometrics, covariance descriptor, face verification, FRGC, GMM, modeling, performance evaluation, region-covariance matrix @inproceedings{krizajrobust,The paper presents a novel framework to 3D face recognition that exploits region covariance matrices (RCMs), Gaussian mixture models (GMMs) and support vector machine (SVM) classifiers. The proposed framework first combines several 3D face representations at the feature level using RCM descriptors and then derives low-dimensional feature vectors from the computed descriptors with the unscented transform. By doing so, it enables computations in Euclidean space, and makes Gaussian mixture modeling feasible. Finally, a support vector classifier is used for identity inference. As demonstrated by our experimental results on the FRGCv2 and UMB databases, the proposed framework is highly robust and exhibits desirable characteristics such as an inherent mechanism for data fusion (through the RCMs), the ability to examine local as well as global structures of the face with the same descriptor, the ability to integrate domain-specific prior knowledge into the modeling procedure and consequently to handle missing or unreliable data. |
Štruc, Vitomir; Žganec-Gros, Jerneja; Pavešić, Nikola; Dobrišek, Simon Zlivanje informacij za zanseljivo in robustno razpoznavanje obrazov Članek v strokovni reviji V: Electrotechnical Review, vol. 80, no. 3, str. 1-12, 2013. Povzetek | Povezava | BibTeX | Oznake: biometrics, face recognition, fusion, performance evaluation @article{EV_Struc_2013,The existing face recognition technology has reached a performance level where it is possible to deploy it in various applications providing they are capable of ensuring controlled conditions for the image acquisition procedure. However, the technology still struggles with its recognition performance when deployed in uncontrolled and unconstrained conditions. In this paper, we present a novel approach to face recognition designed specifically for these challenging conditions. The proposed approach exploits information fusion to achieve robustness. In the first step, the approach crops the facial region from each input image in three different ways. It then maps each of the three crops into one of four color representations and finally extracts several feature types from each of the twelve facial representations. The described procedure results in a total of thirty facial representations that are combined at the matching score level using a fusion approach based on linear logistic regression (LLR) to arrive at a robust decision regarding the identity of the subject depicted in the input face image. The presented approach was enlisted as a representative of the University of Ljubljana and Alpineon d.o.o. to the 2013 face-recognition competition that was held in conjunction with the IAPR International Conference on Biometrics and achieved the best overall recognition results among all competition participants. Here, we describe the basic characteristics of the approach, elaborate on the results of the competition and, most importantly, present some interesting findings made during our development work that are also of relevance to the research community working in the field of face recognition. |
Štruc, Vitomir; Gros, Jeneja Žganec; Dobrišek, Simon; Pavešić, Nikola Exploiting representation plurality for robust and efficient face recognition Proceedings Article V: Proceedings of the 22nd Intenational Electrotechnical and Computer Science Conference (ERK'13), str. 121–124, Portorož, Slovenia, 2013. Povzetek | Povezava | BibTeX | Oznake: competition, erk, face recognition, face verification, group evaluation, ICB, mobile biometrics, MOBIO, performance evaluation @inproceedings{ERK2013_Struc,The paper introduces a novel approach to face recognition that exploits plurality of representation to achieve robust face recognition. The proposed approach was submitted as a representative of the University of Ljubljana and Alpineon d.o.o. to the 2013 face recognition competition that was held in conjunction with the IAPR International Conference on Biometrics and achieved the best overall recognition results among all competition participants. Here, we describe the basic characteristics of the submitted approach, elaborate on the results of the competition and, most importantly, present some general findings made during our development work that are of relevance to the broader (face recognition) research community. |
Križaj, Janez; Štruc, Vitomir; Dobrišek, Simon Combining 3D face representations using region covariance descriptors and statistical models Proceedings Article V: Proceedings of the IEEE International Conference on Automatic Face and Gesture Recognition and Workshops (IEEE FG), Workshop on 3D Face Biometrics, IEEE, Shanghai, China, 2013. Povzetek | Povezava | BibTeX | Oznake: 3d face recognition, biometrics, covariance descriptors, face recognition, face verification, FG, gaussian mixture models, GMM, unscented transform @inproceedings{FG2013,The paper introduces a novel framework for 3D face recognition that capitalizes on region covariance descriptors and Gaussian mixture models. The framework presents an elegant and coherent way of combining multiple facial representations, while simultaneously examining all computed representations at various levels of locality. The framework first computes a number of region covariance matrices/descriptors from different sized regions of several image representations and then adopts the unscented transform to derive low-dimensional feature vectors from the computed descriptors. By doing so, it enables computations in the Euclidean space, and makes Gaussian mixture modeling feasible. In the last step a support vector machine classification scheme is used to make a decision regarding the identity of the modeled input 3D face image. The proposed framework exhibits several desirable characteristics, such as an inherent mechanism for data fusion/integration (through the region covariance matrices), the ability to examine the facial images at different levels of locality, and the ability to integrate domain-specific prior knowledge into the modeling procedure. We assess the feasibility of the proposed framework on the Face Recognition Grand Challenge version 2 (FRGCv2) database with highly encouraging results. |
Dobrišek, Simon; Gajšek, Rok; Mihelič, France; Pavešić, Nikola; Štruc, Vitomir Towards efficient multi-modal emotion recognition Članek v strokovni reviji V: International Journal of Advanced Robotic Systems, vol. 10, no. 53, 2013. Povzetek | Povezava | BibTeX | Oznake: avid database, emotion recognition, facial expression recognition, multi modality, speech technologies @article{dobrivsek2013towards,The paper presents a multi-modal emotion recognition system exploiting audio and video (i.e., facial expression) information. The system first processes both sources of information individually to produce corresponding matching scores and then combines the computed matching scores to obtain a classification decision. For the video part of the system, a novel approach to emotion recognition, relying on image-set matching, is developed. The proposed approach avoids the need for detecting and tracking specific facial landmarks throughout the given video sequence, which represents a common source of error in video-based emotion recognition systems, and, therefore, adds robustness to the video processing chain. The audio part of the system, on the other hand, relies on utterance-specific Gaussian Mixture Models (GMMs) adapted from a Universal Background Model (UBM) via the maximum a posteriori probability (MAP) estimation. It improves upon the standard UBM-MAP procedure by exploiting gender information when building the utterance-specific GMMs, thus ensuring enhanced emotion recognition performance. Both the uni-modal parts as well as the combined system are assessed on the challenging multi-modal eNTERFACE'05 corpus with highly encouraging results. The developed system represents a feasible solution to emotion recognition that can easily be integrated into various systems, such as humanoid robots, smart surveillance systems and alike. |
Peer, Peter; Bule, Jernej; Gros, Jerneja Žganec; Štruc, Vitomir Building cloud-based biometric services Članek v strokovni reviji V: Informatica, vol. 37, no. 2, str. 115, 2013. Povzetek | Povezava | BibTeX | Oznake: biometrics, cloud computing, development. SaaS, face recognition, fingerprint recognition @article{peer2013building,Over the next few years the amount of biometric data being at the disposal of various agencies and authentication service providers is expected to grow significantly. Such quantities of data require not only enormous amounts of storage but unprecedented processing power as well. To be able to face this future challenges more and more people are looking towards cloud computing, which can address these challenges quite effectively with its seemingly unlimited storage capacity, rapid data distribution and parallel processing capabilities. Since the available literature on how to implement cloud-based biometric services is extremely scarce, this paper capitalizes on the most important challenges encountered during the development work on biometric services, presents the most important standards and recommendations pertaining to biometric services in the cloud and ultimately, elaborates on the potential value of cloud-based biometric solutions by presenting a few existing (commercial) examples. In the final part of the paper, a case study on fingerprint recognition in the cloud and its integration into the e-learning environment Moodle is presented. |
Kenk, Vildana Sulič; Križaj, Janez; Štruc, Vitomir; Dobrišek, Simon Smart surveillance technologies in border control Članek v strokovni reviji V: European Journal of Law and Technology, vol. 4, no. 2, 2013. Povzetek | Povezava | BibTeX | Oznake: border control, proportionality, smart surveillance, surveillance, surveillance technology @article{kenk2013smart,The paper addresses the technical and legal aspects of the existing and forthcoming intelligent ('smart') surveillance technologies that are (or are considered to be) employed in the border control application area. Such technologies provide a computerized decision-making support to border control authorities, and are intended to increase the reliability and efficiency of border control measures. However, the question that arises is how effective these technologies are, as well as at what price, economically, socially, and in terms of citizens' rights. The paper provides a brief overview of smart surveillance technologies in border control applications, especially those used for controlling cross-border traffic, discusses possible proportionality issues and privacy risks raised by the increasingly widespread use of such technologies, as well as good/best practises developed in this area. In a broader context, the paper presents the result of the research carried out as part of the SMART (Scalable Measures for Automated Recognition Technologies) project. |
Štruc, Vitomir; Pavešić, Nikola; Žganec-Gros, Jerneja; Vesnicer, Boštjan Patch-wise low-dimensional probabilistic linear discriminant analysis for Face Recognition Proceedings Article V: 2013 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), str. 2352–2356, IEEE 2013. Povzetek | Povezava | BibTeX | Oznake: biometrics, face verification, FRGC, ICASSP, patch-wise approach, plda, probabilistic linear discriminant analysis @inproceedings{vstruc2013patch,The paper introduces a novel approach to face recognition based on the recently proposed low-dimensional probabilistic linear discriminant analysis (LD-PLDA). The proposed approach is specifically designed for complex recognition tasks, where highly nonlinear face variations are typically encountered. Such data variations are commonly induced by changes in the external illumination conditions, viewpoint changes or expression variations and represent quite a challenge even for state-of-the-art techniques, such as LD-PLDA. To overcome this problem, we propose here a patch-wise form of the LDPLDA technique (i.e., PLD-PLDA), which relies on local image patches rather than the entire image to make inferences about the identity of the input images. The basic idea here is to decompose the complex face recognition problem into simpler problems, for which the linear nature of the LD-PLDA technique may be better suited. By doing so, several similarity scores are derived from one facial image, which are combined at the final stage using a simple sum-rule fusion scheme to arrive at a single score that can be employed for identity inference. We evaluate the proposed technique on experiment 4 of the Face Recognition Grand Challenge (FRGCv2) database with highly promising results. |
Günther, Manuel; Costa-Pazo, Artur; Ding, Changxing; Boutellaa, Elhocine; Chiachia, Giovani; Zhang, Honglei; de Angeloni, Marcus Assis; Štruc, Vitomir; Khoury, Elie; Vazquez-Fernandez, Esteban; others, The 2013 face recognition evaluation in mobile environment Proceedings Article V: Proceedings of the IAPR International Conference on Biometrics (ICB), str. 1–7, IAPR 2013. Povzetek | Povezava | BibTeX | Oznake: biometrics, competition, face recognition, face verification, group evaluation, mobile biometrics, MOBIO, performance evaluation @inproceedings{gunther20132013,Automatic face recognition in unconstrained environments is a challenging task. To test current trends in face recognition algorithms, we organized an evaluation on face recognition in mobile environment. This paper presents the results of 8 different participants using two verification metrics. Most submitted algorithms rely on one or more of three types of features: local binary patterns, Gabor wavelet responses including Gabor phases, and color information. The best results are obtained from UNILJ-ALP, which fused several image representations and feature types, and UCHU, which learns optimal features with a convolutional neural network. Additionally, we assess the usability of the algorithms in mobile devices with limited resources. |
Stres, Blaz; Sul, Woo Jun; Murovec, Bostjan; Tiedje, James M Recently Deglaciated High-Altitude Soils of the Himalaya: Diverse Environments, Heterogenous Bacterial Communities and Long-Range Dust Inputs from the Upper Troposphere Članek v strokovni reviji V: PLOS ONE, vol. 8, no. 9, str. 1-10, 2013. Povzetek | Povezava | BibTeX | Oznake: @article{10.1371/journal.pone.0076440,Background The Himalaya with its altitude and geographical position forms a barrier to atmospheric transport, which produces much aqueous-particle monsoon precipitation and makes it the largest continuous ice-covered area outside polar regions. There is a paucity of data on high-altitude microbial communities, their native environments and responses to environmental-spatial variables relative to seasonal and deglaciation events. Methodology/Principal Findings Soils were sampled along altitude transects from 5000 m to 6000 m to determine environmental, spatial and seasonal factors structuring bacterial communities characterized by 16 S rRNA gene deep sequencing. Dust traps and fresh-snow samples were used to assess dust abundance and viability, community structure and abundance of dust associated microbial communities. Significantly different habitats among the altitude-transect samples corresponded to both phylogenetically distant and closely-related communities at distances as short as 50 m showing high community spatial divergence. High within-group variability that was related to an order of magnitude higher dust deposition obscured seasonal and temporal rearrangements in microbial communities. Although dust particle and associated cell deposition rates were highly correlated, seasonal dust communities of bacteria were distinct and differed significantly from recipient soil communities. Analysis of closest relatives to dust OTUs, HYSPLIT back-calculation of airmass trajectories and small dust particle size (4–12 µm) suggested that the deposited dust and microbes came from distant continental, lacustrine and marine sources, e.g. Sahara, India, Caspian Sea and Tibetan plateau. Cyanobacteria represented less than 0.5% of microbial communities suggesting that the microbial communities benefitted from (co)deposited carbon which was reflected in the psychrotolerant nature of dust-particle associated bacteria. Conclusions/Significance The spatial, environmental and temporal complexity of the high-altitude soils of the Himalaya generates ongoing disturbance and colonization events that subject heterogeneous microniches to stochastic colonization by far away dust associated microbes and result in the observed spatially divergent bacterial communities. |
Murovec, Boštjan; Perš, Janez; Mandeljc, Rok; Kenk, Vildana Sulić; Kovačič, Stanislav Towards commoditized smart-camera design Članek v strokovni reviji V: Journal of Systems Architecture, vol. 59, no. 10, Part A, str. 847 - 858, 2013, ISSN: 1383-7621, (Smart Camera Architecture). Povzetek | Povezava | BibTeX | Oznake: Commoditized smart camera, Design principles, General-purpose smart camera, Reference design, Visual-sensor networks @article{MUROVEC2013847,We propose a set of design principles for a cost-effective embedded smart camera. Our aim is to alleviate the shortcomings of the existing designs, such as excessive reliance on battery power and wireless networking, over-emphasized focus on specific use cases, and use of specialized technologies. In our opinion, these shortcomings prevent widespread commercialization and adoption of embedded smart cameras, especially in the context of visual-sensor networks. The proposed principles lead to a distinctively different design, which relies on commoditized, standardized and widely-available components, tools and knowledge. As an example of using these principles in practice, we present a smart camera, which is inexpensive, easy to build and support, capable of high-speed communication and enables rapid transfer of computer-vision algorithms to the embedded world. |
2012 |
Križaj, Janez; Štruc, Vitomir; Dobrišek, Simon Robust 3D Face Recognition Članek v strokovni reviji V: Electrotechnical Review, vol. 79, no. 1-2, str. 1-6, 2012. Povzetek | Povezava | BibTeX | Oznake: 3d face recognition, biometrics, gaussian mixture models, GMM, modeling @article{Križaj-EV-2012,Face recognition in uncontrolled environments is hindered by variations in illumination, pose, expression and occlusions of faces. Many practical face-recognition systems are affected by these variations. One way to increase the robustness to illumination and pose variations is to use 3D facial images. In this paper 3D face-recognition systems are presented. Their structure and operation are described. The robustness of such systems to variations in uncontrolled environments is emphasized. We present some preliminary results of a system developed in our laboratory. |
Križaj, Janez; Štruc, Vitomir; Dobrišek, Simon Towards robust 3D face verification using Gaussian mixture models Članek v strokovni reviji V: International Journal of Advanced Robotic Systems, vol. 9, 2012. Povzetek | Povezava | BibTeX | Oznake: @article{krizaj2012towards,This paper focuses on the use of Gaussian Mixture models (GMM) for 3D face verification. A special interest is taken in practical aspects of 3D face verification systems, where all steps of the verification procedure need to be automated and no meta-data, such as pre-annotated eye/nose/mouth positions, is available to the system. In such settings the performance of the verification system correlates heavily with the performance of the employed alignment (i.e., geometric normalization) procedure. We show that popular holistic as well as local recognition techniques, such as principal component analysis (PCA), or Scale-invariant feature transform (SIFT)-based methods considerably deteriorate in their performance when an “imperfect” geometric normalization procedure is used to align the 3D face scans and that in these situations GMMs should be preferred. Moreover, several possibilities to improve the performance and robustness of the classical GMM framework are presented and evaluated: i) explicit inclusion of spatial information, during the GMM construction procedure, ii) implicit inclusion of spatial information during the GMM construction procedure and iii) on-line evaluation and possible rejection of local feature vectors based on their likelihood. We successfully demonstrate the feasibility of the proposed modifications on the Face Recognition Grand Challenge data set. |
Vesnicer, Bostjan; Gros, Jerneja Žganec; Pavešić, Nikola; Štruc, Vitomir Face recognition using simplified probabilistic linear discriminant analysis Članek v strokovni reviji V: International Journal of Advanced Robotic Systems, vol. 9, 2012. Povzetek | Povezava | BibTeX | Oznake: biometrics, face recognition, plda, simplified PLDA @article{vesnicer2012face,Face recognition in uncontrolled environments remains an open problem that has not been satisfactorily solved by existing recognition techniques. In this paper, we tackle this problem using a variant of the recently proposed Probabilistic Linear Discriminant Analysis (PLDA). We show that simplified versions of the PLDA model, which are regularly used in the field of speaker recognition, rely on certain assumptions that not only result in a simpler PLDA model, but also reduce the computational load of the technique and - as indicated by our experimental assessments - improve recognition performance. Moreover, we show that, contrary to the general belief that PLDA-based methods produce well calibrated verification scores, score normalization techniques can still deliver significant performance gains, but only if non-parametric score normalization techniques are employed. Last but not least, we demonstrate the competitiveness of the simplified PLDA model for face recognition by comparing our results with the state-of-the-art results from the literature obtained on the second version of the large-scale Face Recognition Grand Challenge (FRGC) database. |
2011 |
Štruc, Vitomir; Pavešić, Nikola Photometric normalization techniques for illumination invariance Book Section V: Zhang, Yu-Jin (Ur.): Advances in Face Image Analysis: Techniques and Technologies, str. 279-300, IGI-Global, 2011. Povzetek | Povezava | BibTeX | Oznake: biometrics, face recognition, illumination invariance, illumination normalization, photometric normalization @incollection{IGI2011,Face recognition technology has come a long way since its beginnings in the previous century. Due to its countless application possibilities, it has attracted the interest of research groups from universities and companies around the world. Thanks to this enormous research effort, the recognition rates achievable with the state-of-the-art face recognition technology are steadily growing, even though some issues still pose major challenges to the technology. Amongst these challenges, coping with illumination-induced appearance variations is one of the biggest and still not satisfactorily solved. A number of techniques have been proposed in the literature to cope with the impact of illumination ranging from simple image enhancement techniques, such as histogram equalization, to more elaborate methods, such as anisotropic smoothing or the logarithmic total variation model. This chapter presents an overview of the most popular and efficient normalization techniques that try to solve the illumination variation problem at the preprocessing level. It assesses the techniques on the YaleB and XM2VTS databases and explores their strengths and weaknesses from the theoretical and implementation point of view. |
Štruc, Vitomir; Žganec-Gros, Jerneja; Pavešić, Nikola Principal directions of synthetic exact filters for robust real-time eye localization Proceedings Article V: Proceedings of the COST workshop on Biometrics and Identity Management (BioID), str. 180/192, Springer-Verlag, Berlin, Heidelberg, 2011. Povzetek | Povezava | BibTeX | Oznake: ASEF, correlation filters, eye localization, face image processing, landmark localization, landmarking, PSEF @inproceedings{BioID_Struc_2011,The alignment of the facial region with a predefined canonical form is one of the most crucial steps in a face recognition system. Most of the existing alignment techniques rely on the position of the eyes and, hence, require an efficient and reliable eye localization procedure. In this paper we propose a novel technique for this purpose, which exploits a new class of correlation filters called Principal directions of Synthetic Exact Filters (PSEFs). The proposed filters represent a generalization of the recently proposed Average of Synthetic Exact Filters (ASEFs) and exhibit desirable properties, such as relatively short training times, computational simplicity, high localization rates and real time capabilities. We present the theory of PSEF filter construction, elaborate on their characteristics and finally develop an efficient procedure for eye localization using several PSEF filters. We demonstrate the effectiveness of the proposed class of correlation filters for the task of eye localization on facial images from the FERET database and show that for the tested task they outperform the established Haar cascade object detector as well as the ASEF correlation filters. |
2010 |
Štruc, Vitomir; Pavešić, Nikola Face recogniton from color images using sparse projection analysis Proceedings Article V: Proceedings of the 7th International Conference on Image Analysis and Recognition (ICIAR 2010), str. 445-453, Povoa de Varzim, Portugal, 2010. Povzetek | Povezava | BibTeX | Oznake: biometrics, face verification, ICIAR, performance evaluation, sparse projection analysis @inproceedings{ICIAR2010_Sparse,The paper presents a novel feature extraction technique for face recognition which uses sparse projection axes to compute a lowdimensional representation of face images. The proposed technique derives the sparse axes by first recasting the problem of face recognition as a regression problem and then solving the new (under-determined) regression problem by computing the solution with minimum L1 norm. The developed technique, named Sparse Projection Analysis (SPA), is applied to color as well as grey-scale images from the XM2VTS database and compared to popular subspace projection techniques (with sparse and dense projection axes) from the literature. The results of the experimental assessment show that the proposed technique ensures promising results on un-occluded as well occluded images from the XM2VTS database. |
Križaj, Janez; Štruc, Vitomir; Pavešić, Nikola Adaptation of SIFT Features for Robust Face Recognition Proceedings Article V: Proceedings of the 7th International Conference on Image Analysis and Recognition (ICIAR 2010), str. 394-404, Povoa de Varzim, Portugal, 2010. Povzetek | Povezava | BibTeX | Oznake: biometrics, dense SIFT, face recognition, performance evaluation, SIFT, SIFT features @inproceedings{ICIAR2010_Sift,The Scale Invariant Feature Transform (SIFT) is an algorithm used to detect and describe scale-, translation- and rotation-invariant local features in images. The original SIFT algorithm has been successfully applied in general object detection and recognition tasks, panorama stitching and others. One of its more recent uses also includes face recognition, where it was shown to deliver encouraging results. SIFT-based face recognition techniques found in the literature rely heavily on the so-called keypoint detector, which locates interest points in the given image that are ultimately used to compute the SIFT descriptors. While these descriptors are known to be among others (partially) invariant to illumination changes, the keypoint detector is not. Since varying illumination is one of the main issues affecting the performance of face recognition systems, the keypoint detector represents the main source of errors in face recognition systems relying on SIFT features. To overcome the presented shortcoming of SIFT-based methods, we present in this paper a novel face recognition technique that computes the SIFT descriptors at predefined (fixed) locations learned during the training stage. By doing so, it eliminates the need for keypoint detection on the test images and renders our approach more robust to illumination changes than related approaches from the literature. Experiments, performed on the Extended Yale B face database, show that the proposed technique compares favorably with several popular techniques from the literature in terms of performance. |
Štruc, Vitomir; Vesnicer, Boštjan; Mihelič, France; Pavešić, Nikola Removing Illumination Artifacts from Face Images using the Nuisance Attribute Projection Proceedings Article V: Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP'10), str. 846-849, IEEE, Dallas, Texas, USA, 2010. Povzetek | Povezava | BibTeX | Oznake: biometrics, face recognition, face verification, illumination changes, illumination invariance, nuisance attribute projection, robust recognition @inproceedings{ICASSP2010,Illumination induced appearance changes represent one of the open challenges in automated face recognition systems still significantly influencing their performance. Several techniques have been presented in the literature to cope with this problem; however, a universal solution remains to be found. In this paper we present a novel normalization scheme based on the nuisance attribute projection (NAP), which tries to remove the effects of illumination by projecting away multiple dimensions of a low dimensional illumination subspace. The technique is assessed in face recognition experiments performed on the extended YaleB and XM2VTS databases. Comparative results with state-of-the-art techniques show the competitiveness of the proposed technique. |
Štruc, Vitomir; Pavešić, Nikola V: Oravec, Milos (Ur.): Face Recognition, str. 215-238, In-Tech, Vienna, 2010. Povezava | BibTeX | Oznake: biometrics, face recognition, feature extraction, Gabor features, Gabor filters, illumination changes, phase features @incollection{InTech2010, |
Štruc, Vitomir; Pavešić, Nikola The Complete Gabor-Fisher Classifier for Robust Face Recognition Članek v strokovni reviji V: EURASIP Advances in Signal Processing, vol. 2010, str. 26, 2010. Povzetek | Povezava | BibTeX | Oznake: biometrics, combined model, face recognition, feature extraction, Gabor features, phase features @article{CGF-Struc_2010,This paper develops a novel face recognition technique called Complete Gabor Fisher Classifier (CGFC). Different from existing techniques that use Gabor filters for deriving the Gabor face representation, the proposed approach does not rely solely on Gabor magnitude information but effectively uses features computed based on Gabor phase information as well. It represents one of the few successful attempts found in the literature of combining Gabor magnitude and phase information for robust face recognition. The novelty of the proposed CGFC technique comes from (1) the introduction of a Gabor phase-based face representation and (2) the combination of the recognition technique using the proposed representation with classical Gabor magnitude-based methods into a unified framework. The proposed face recognition framework is assessed in a series of face verification and identification experiments performed on the XM2VTS, Extended YaleB, FERET, and AR databases. The results of the assessment suggest that the proposed technique clearly outperforms state-of-the-art face recognition techniques from the literature and that its performance is almost unaffected by the presence of partial occlusions of the facial area, changes in facial expression, or severe illumination changes. |
Poh, Norman; Chan, Chi Ho; Kittler, Josef; Marcel, Sebastien; Cool, Christopher Mc; Rua, Enrique Argones; Castro, Jose Luis Alba; Villegas, Mauricio; Paredes, Roberto; Struc, Vitomir; others, An evaluation of video-to-video face verification Članek v strokovni reviji V: IEEE Transactions on Information Forensics and Security, vol. 5, no. 4, str. 781–801, 2010. Povzetek | Povezava | BibTeX | Oznake: biometrics, competition, face recognition, face verification, group evaluation, video @article{poh2010evaluation,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 realize facial video recognition, rather than resorting to just still images. In fact, facial video recognition offers many advantages over still image recognition; these include the potential of boosting the system accuracy and deterring spoof attacks. This paper presents an evaluation of person identity verification using facial video data, organized in conjunction with the International Conference on Biometrics (ICB 2009). It involves 18 systems submitted by seven academic institutes. These systems provide for a diverse set of assumptions, including feature representation and preprocessing variations, allowing us to assess the effect of adverse conditions, usage of quality information, query selection, and template construction for video-to-video face authentication. |
Štruc, Vitomir; Dobrišek, Simon; Pavešić, Nikola Confidence Weighted Subspace Projection Techniques for Robust Face Recognition in the Presence of Partial Occlusions Proceedings Article V: Proceedings of the International Conference on Pattern Recognition (ICPR'10), str. 1334-1338, Istanbul, Turkey, 2010. Povezava | BibTeX | Oznake: biometrics, face recognition, face verification, ICPR, performance evaluation, subspace projection @inproceedings{ICPR_Struc_2010, |
Gajšek, Rok; Štruc, Vitomir; Mihelič, France Multi-modal Emotion Recognition using Canonical Correlations and Acustic Features Proceedings Article V: Proceedings of the International Conference on Pattern Recognition (ICPR), str. 4133-4136, IAPR Istanbul, Turkey, 2010. Povzetek | Povezava | BibTeX | Oznake: acustic features, canonical correlations, emotion recognition, facial expression recognition, multi modality, speech processing, speech technologies @inproceedings{ICPR_Gajsek_2010,The information of the psycho-physical state of the subject is becoming a valuable addition to the modern audio or video recognition systems. As well as enabling a better user experience, it can also assist in superior recognition accuracy of the base system. In the article, we present our approach to multi-modal (audio-video) emotion recognition system. For audio sub-system, a feature set comprised of prosodic, spectral and cepstrum features is selected and support vector classifier is used to produce the scores for each emotional category. For video sub-system a novel approach is presented, which does not rely on the tracking of specific facial landmarks and thus, eliminates the problems usually caused, if the tracking algorithm fails at detecting the correct area. The system is evaluated on the eNTERFACE database and the recognition accuracy of our audio-video fusion is compared to the published results in the literature. |
Gajšek, Rok; Štruc, Vitomir; Mihelič, France Multi-modal Emotion Recognition based on the Decoupling of Emotion and Speaker Information Proceedings Article V: Proceedings of Text, Speech and Dialogue (TSD), str. 275-282, Springer-Verlag, Berlin, Heidelberg, 2010. Povzetek | Povezava | BibTeX | Oznake: emotion recognition, facial expression recognition, multi modality, speech processing, speech technologies, spontaneous emotions, video processing @inproceedings{TSD_Emo_Gajsek,The standard features used in emotion recognition carry, besides the emotion related information, also cues about the speaker. This is expected, since the nature of emotionally colored speech is similar to the variations in the speech signal, caused by different speakers. Therefore, we present a gradient descent derived transformation for the decoupling of emotion and speaker information contained in the acoustic features. The Interspeech ’09 Emotion Challenge feature set is used as the baseline for the audio part. A similar procedure is employed on the video signal, where the nuisance attribute projection (NAP) is used to derive the transformation matrix, which contains information about the emotional state of the speaker. Ultimately, different NAP transformation matrices are compared using canonical correlations. The audio and video sub-systems are combined at the matching score level using different fusion techniques. The presented system is assessed on the publicly available eNTERFACE’05 database where significant improvements in the recognition performance are observed when compared to the stat-of-the-art baseline. |
Štruc, Vitomir; Žganec-Gros, Jerneja; Pavešić, Nikola Eye Localization using correlation filters Proceedings Article V: Proceedings of the International Conference DOGS, str. 188-191, Novi Sad, Serbia, 2010. BibTeX | Oznake: ASEF, correlation filters, eye localization, face image processing, landmark localization, PSEF @inproceedings{DOGS_Struc_2010, |
Murovec, Boštjan; Tiedje, James M; Stres, Blaž DNA encoding for an efficient 'Omics processing Članek v strokovni reviji V: Computer Methods and Programs in Biomedicine, vol. 100, no. 2, str. 175 - 190, 2010, ISSN: 0169-2607. Povzetek | Povezava | BibTeX | Oznake: Binary DNA encoding, Binary nucleotide encoding, DNA-64, NumFASTA @article{MUROVEC2010175,The exponential growth of available DNA sequences and the increased interoperability of biological information is triggering intergovernmental efforts aimed at increasing the access, dissemination, and analysis of sequence data. Achieving the efficient storage and processing of DNA material is an important goal that parallels well with the foreseen coding standardization on the horizon. This paper proposes novel coding approaches, for both the dissemination and processing of sequences, where the speed of the DNA processing is shown to be boosted by exploring more than the normally utilized eight bits for encoding a single nucleotide. Further gains are achieved by encoding the nucleotides together with their trailing alignment information as a single 64-bit data structure. The paper also proposes a slight modification to the established FASTA scheme in order to improve on its representation of alignment information. The significance of the propositions is confirmed by the encouraging results from empirical tests. |
2009 |
Štruc, Vitomir; Gajšek, Rok; Pavešić, Nikola Principal Gabor Filters for Face Recognition Proceedings Article V: Proceedings of the 3rd IEEE International Conference on Biometrics: Theory, Systems and Applications (BTAS'09), str. 1-6, IEEE, Washington D.C., U.S.A., 2009. Povzetek | Povezava | BibTeX | Oznake: biometrics, face verification, feature extraction, Gabor features, performance evaluation, principal Gabor filters @inproceedings{BTAS2009,Gabor filters have proven themselves to be a powerful tool for facial feature extraction. An abundance of recognition techniques presented in the literature exploits these filters to achieve robust face recognition. However, while exhibiting desirable properties, such as orientational selectivity or spatial locality, Gabor filters have also some shortcomings which crucially affect the characteristics and size of the Gabor representation of a given face pattern. Amongst these shortcomings the fact that the filters are not orthogonal one to another and are, hence, correlated is probably the most important. This makes the information contained in the Gabor face representation redundant and also affects the size of the representation. To overcome this problem we propose in this paper to employ orthonormal linear combinations of the original Gabor filters rather than the filters themselves for deriving the Gabor face representation. The filters, named principal Gabor filters for the fact that they are computed by means of principal component analysis, are assessed in face recognition experiments performed on the XM2VTS and YaleB databases, where encouraging results are achieved. |
Gajšek, Rok; Štruc, Vitomir; Dobrišek, Simon; Mihelič, France Emotion recognition using linear transformations in combination with video Proceedings Article V: Speech and intelligence: proceedings of Interspeech 2009, str. 1967-1970, Brighton, UK, 2009. Povzetek | Povezava | BibTeX | Oznake: emotion recognition, facial expression recognition, interspeech, speech, speech technologies, spontaneous emotions @inproceedings{InterSp2009,The paper discuses the usage of linear transformations of Hidden Markov Models, normally employed for speaker and environment adaptation, as a way of extracting the emotional components from the speech. A constrained version of Maximum Likelihood Linear Regression (CMLLR) transformation is used as a feature for classification of normal or aroused emotional state. We present a procedure of incrementally building a set of speaker independent acoustic models, that are used to estimate the CMLLR transformations for emotion classification. An audio-video database of spontaneous emotions (AvID) is briefly presented since it forms the basis for the evaluation of the proposed method. Emotion classification using the video part of the database is also described and the added value of combining the visual information with the audio features is shown. |
Štruc, Vitomir; Ma, Zongmin; Pavešić, Nikola Nuisance Attribute Projection in the Logarithm Domain for Face Recognition under Severe Illumination Changes Proceedings Article V: Proceedings of the IEEE International Electrotechnical and Computer Science Conference (ERK'09), str. 279-281, Portorož, Slovenia, 2009. BibTeX | Oznake: biometrics, face verification, illumination changes, illumination invariance, nuisance attribute projection, performance evaluation, robust recognition @inproceedings{ERK2009N, |
Štruc, Vitomir; Ma, Zongmin; Pavešić, Nikola Face Recognition using Sparse Projection Axes Proceedings Article V: Proceedings of the IEEE International Electrotechnical and Computer Science Conference (ERK'09), str. 271-274, Portorož, Slovenia, 2009. BibTeX | Oznake: biometrics, erk, face recognition, face verification, performance evaluation, sparse projection analysis @inproceedings{ERK2009S, |
Štruc, Vitomir; Pavešić, Nikola A comparative assessment of appearance based feature extraction techniques and their susceptibility to image degradations in face recognition systems Proceedings Article V: Proceedings of the International Conference on Machine Learning and Pattern Recognition (ICMLPR'09), str. 326-334, Paris, France, 2009. Povzetek | Povezava | BibTeX | Oznake: biometrics, face recognition, face verification, image degradations, performance evaluation @inproceedings{FSKD208b,Over the past decades, automatic face recognition has become a highly active research area, mainly due to the countless application possibilities in both the private as well as the public sector. Numerous algorithms have been proposed in the literature to cope with the problem of face recognition, nevertheless, a group of methods commonly referred to as appearance based have emerged as the dominant solution to the face recognition problem. Many comparative studies concerned with the performance of appearance based methods have already been presented in the literature, not rarely with inconclusive and often with contradictory results. No consent has been reached within the scientific community regarding the relative ranking of the efficiency of appearance based methods for the face recognition task, let alone regarding their susceptibility to appearance changes induced by various environmental factors. To tackle these open issues, this paper assess the performance of the three dominant appearance based methods: principal component analysis, linear discriminant analysis and independent component analysis, and compares them on equal footing (i.e., with the same preprocessing procedure, with optimized parameters for the best possible performance, etc.) in face verification experiments on the publicly available XM2VTS database. In addition to the comparative analysis on the XM2VTS database, ten degraded versions of the database are also employed in the experiments to evaluate the susceptibility of the appearance based methods on various image degradations which can occur in ”real-life” operating conditions. Our experimental results suggest that linear discriminant analysis ensures the most consistent verification rates across the tested databases. |
Štruc, Vitomir; Pavešić, Nikola A comparison of feature normalization techniques for PCA-based palmprint recognition Proceedings Article V: Proceedings of the International Conference on Mathematical Modeling (MATHMOD'09), str. 2450-2453, Viena, Austria, 2009. Povzetek | Povezava | BibTeX | Oznake: biometrics, face verification, feature normalization, normalization, pca, performance evaluation @inproceedings{Mathmod09,Computing user templates (or models) for biometric authentication systems is one of the most crucial steps towards efficient and accurate biometric recognition. The constructed templates should encode user specific information extracted from a sample of a given biometric modality, such as, for example, palmprints, and exhibit a sufficient level of dissimilarity with other templates stored in the systems database. Clearly, the characteristics of the user templates depend on the approach employed for the extraction of biometric features, as well as on the procedure used to normalize the extracted feature vectors. While feature-extraction methods are a well studied topic, for which a vast amount of comparative studies can be found in the literature, normalization techniques lack such studies and are only briefly mentioned in most cases. In this paper we, therefore, apply several normalization techniques to feature vectors extracted from palmprint images by means of principal component analysis (PCA) and perform a comparative analysis on the results. We show that the choice of an appropriate normalization technique greatly influences the performance of the palmprint-based authentication system and can result in error rate reductions of more than 30%. |
Štruc, Vitomir; Pavešić, Nikola Image normalization techniques for robust face recognition Proceedings Article V: Proceedings of the International Conference on Signal Processing, Robotics and Automation (ISPRA'09), str. 155-160, Cambridge, UK, 2009. BibTeX | Oznake: biometrics, face recognition, face verification, histogram remapping, performance evaluation, preprocessing @inproceedings{ISPRA09, |
Štruc, Vitomir; Pavešić, Nikola Hand-Geometry Device Book Section V: Li, Stan Z (Ur.): Encyclopedia of biometrics, str. 693-698, Springer-Verlag, New York, 2009. Povzetek | Povezava | BibTeX | Oznake: biometrics, device, encyclopedia, hand geometry, sensor @incollection{Springer2009,Hand-geometry devices are specially designed biometric devices used for capturing the geometric characteristics (e.g., the length, width, thickness and curvature of the fingers, the palm size, and the distances between joints) of a human hand for hand-geometry-based identity verification. A typical hand-geometry device records images of the lateral and dorsal parts of the hand with a charge-coupled device (CCD) camera that is mounted above a flat surface on which the person presented to the device places his/her hand. The set of geometrical features extracted from these images is then matched against a pre-recorded template stored in the device’s database. Depending on the result of this matching procedure, the identity of the person presented to the device is either verified or not. |
Štruc, Vitomir; Pavešić, Nikola Gabor-based kernel-partial-least-squares discrimination features for face recognition Članek v strokovni reviji V: Informatica (Vilnius), vol. 20, no. 1, str. 115-138, 2009. Povzetek | Povezava | BibTeX | Oznake: biometrics, face recogntiion, kernel partial least squares, kpca, lda, pca @article{Inform-Struc_2009,The paper presents a novel method for the extraction of facial features based on the Gabor-wavelet representation of face images and the kernel partial-least-squares discrimination (KPLSD) algorithm. The proposed feature-extraction method, called the Gabor-based kernel partial-least-squares discrimination (GKPLSD), is performed in two consecutive steps. In the first step a set of forty Gabor wavelets is used to extract discriminative and robust facial features, while in the second step the kernel partial-least-squares discrimination technique is used to reduce the dimensionality of the Gabor feature vector and to further enhance its discriminatory power. For optimal performance, the KPLSD-based transformation is implemented using the recently proposed fractional-power-polynomial models. The experimental results based on the XM2VTS and ORL databases show that the GKPLSD approach outperforms feature-extraction methods such as principal component analysis (PCA), linear discriminant analysis (LDA), kernel principal component analysis (KPCA) or generalized discriminant analysis (GDA) as well as combinations of these methods with Gabor representations of the face images. Furthermore, as the KPLSD algorithm is derived from the kernel partial-least-squares regression (KPLSR) model it does not suffer from the small-sample-size problem, which is regularly encountered in the field of face recognition. |
Štruc, Vitomir; Žibert, Janez; Pavešić, Nikola Histogram remapping as a preprocessing step for robust face recognition Članek v strokovni reviji V: WSEAS transactions on information science and applications, vol. 6, no. 3, str. 520-529, 2009. Povzetek | Povezava | BibTeX | Oznake: biometrics, face recognition, histogram, histogram remapping, image processing, preprocessing @article{WSEAS-Struc_2009,Image preprocessing techniques represent an essential part of a face recognition systems, which has a great impact on the performance and robustness of the recognition procedure. Amongst the number of techniques already presented in the literature, histogram equalization has emerged as the dominant preprocessing technique and is regularly used for the task of face recognition. With the property of increasing the global contrast of the facial image while simultaneously compensating for the illumination conditions present at the image acquisition stage, it represents a useful preprocessing step, which can ensure enhanced and more robust recognition performance. Even though, more elaborate normalization techniques, such as the multiscale retinex technique, isotropic and anisotropic smoothing, have been introduced to field of face recognition, they have been found to be more of a complement than a real substitute for histogram equalization. However, by closer examining the characteristics of histogram equalization, one can quickly discover that it represents only a specific case of a more general concept of histogram remapping techniques (which may have similar characteristics as histogram equalization does). While histogram equalization remapps the histogram of a given facial image to a uniform distribution, the target distribution could easily be replaced with an arbitrary one. As there is no theoretical justification of why the uniform distribution should be preferred to other target distributions, the question arises: how do other (non-uniform) target distributions influence the face recognition process and are they better suited for the recognition task. To tackle this issues, we present in this paper an empirical assessment of the concept of histogram remapping with the following target distributions: the uniform, the normal, the lognormal and the exponential distribution. We perform comparative experiments on the publicly available XM2VTS and YaleB databases and conclude that similar or even better recognition results that those ensured by histogram equalization can be achieved when other (non-uniform) target distribution are considered for the histogram remapping. This enhanced performance, however, comes at a price, as the nonuniform distributions rely on some parameters which have to be trained or selected appropriately to achieve the optimal performance. |
Gajšek, Rok; Štruc, Vitomir; Mihelič, France; Podlesek, Anja; Komidar, Luka; Sočan, Gregor; Bajec, Boštjan Multi-modal emotional database: AvID Članek v strokovni reviji V: Informatica (Ljubljana), vol. 33, no. 1, str. 101-106, 2009. Povzetek | Povezava | BibTeX | Oznake: avid, database, dataset, emotion recognition, facial expression recognition, speech, speech technologies, spontaneous emotions @article{Inform-Gajsek_2009,This paper presents our work on recording a multi-modal database containing emotional audio and video recordings. In designing the recording strategies a special attention was payed to gather data involving spontaneous emotions and therefore obtain a more realistic training and testing conditions for experiments. With specially planned scenarios including playing computer games and conducting an adaptive intelligence test different levels of arousal were induced. This will enable us to both detect different emotional states as well as experiment in speaker identification/verification of people involved in communications. So far the multi-modal database has been recorded and basic evaluation of the data was processed. |
Štruc, Vitomir; Gajšek, Rok; Mihelič, France; Pavešić, Nikola Using regression techniques for coping with the one-sample-size problem of face recognition Članek v strokovni reviji V: Electrotechnical Review, vol. 76, no. 1-2, str. 7-12, 2009. Povzetek | Povezava | BibTeX | Oznake: biometrics, face recognition, one sample size problem, regression techniques, small sample size @article{EV-Struc_2009,There is a number of face recognition paradigms which ensure good recognition rates with frontal face images. However, the majority of them require an extensive training set and degrade in their performance when an insufficient number of training images is available. This is especially true for applications where only one image per subject is at hand for training. To cope with this one-sample-size (OSS) problem, we propose to employ subspace projection based regression techniques rather than modifications of the established face recognition paradigms, such as the principal component or linear discriminant analysis, as it was done in the past. Experiments performed on the XM2VTS and ORL databases show the effectiveness of the proposed approach. Also presented is a comparative assessment of several regression techniques and some popular face recognition methods. |
Štruc, Vitomir; Pavešić, Nikola Phase-congruency features for palm-print verification Članek v strokovni reviji V: IET Signal Processing, vol. 3, no. 4, str. 258-268, 2009. Povezava | BibTeX | Oznake: biometrics, feature extraction, palmprint verification, palmprints, phase congruency features, recognition @article{IET-Struc_2009, |
Štruc, Vitomir; Pavešić, Nikola Gaussianization of image patches for efficient palmprint recognition Članek v strokovni reviji V: Electrotechnical Review, vol. 76, no. 5, str. 245-250, 2009. Povzetek | Povezava | BibTeX | Oznake: biometrics, gaussianization, histogram remapping, palmprint recognition, palmprints, preprocessing @article{EV_2009_palms,In this paper we present a comparison of the two dominant image preprocessing techniques for palmprint recognition, namely, histogram equalization and mean-variance normalization. We show that both techniques pursue a similar goal and that the difference in recognition efficiency stems from the fact that not all assumptions underlying the mean-variance normalization approach are always met. We present an alternative justification of why histogram equalization ensures enhanced verification performance, and, based on the findings, propose two novel preprocessing techniques: gaussianization of the palmprint images and gaussianization of image patches. We present comparative results obtained on the PolyU database and show that the patch-based normalization technique ensures stat-of-the-art recognition results with a simple feature extraction method and the nearest neighbor classifier. |
Poh, Norman; Chan, Chi Ho; Kittler, Josef; Marcel, Sebastien; McCool, Christopher; Argones-Rua, Enrique; Alba-Castro, Jose Luis; Villegas, Mauricio; Paredes, Roberto; Štruc, Vitomir; Pavešić, Nikola; Salah, Albert Ali; Fang, Hui; Costen, Nicholas Face Video Competition Proceedings Article V: Tistarelli, Massimo; Nixon, Mark (Ur.): Proceedings of the international Conference on Biometrics (ICB), str. 715-724, Springer-Verlag, Berlin, Heidelberg, 2009. Povzetek | Povezava | BibTeX | Oznake: biometrics, competition, face recognition, face verification, ICB, performance evaluation @inproceedings{ICB2009,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 the potential of boosting the system accuracy and deterring spoof attacks. This paper presents the first known benchmarking effort of person identity verification using facial video data. The evaluation involves 18 systems submitted by seven academic institutes. |
Objave
2014 |
Strategies for exploiting independent cloud implementations of biometric experts in multibiometric scenarios Članek v strokovni reviji V: Mathematical problems in engineering, vol. 2014, 2014. |
Beyond parametric score normalisation in biometric verification systems Članek v strokovni reviji V: IET Biometrics, vol. 3, no. 2, str. 62–74, 2014. |
A case study on multi-modal biometrics in the cloud Članek v strokovni reviji V: Electrotechnical Review, vol. 81, no. 3, str. 74, 2014. |
A Feasibility Study on the Use of Binary Keypoint Descriptors for 3D Face Recognition Proceedings Article V: Proceedings of the Mexican Conference on Pattern Recognition (MCPR), str. 142–151, Springer 2014. |
SIFT vs. FREAK: Assessing the usefulness of two keypoint descriptors for 3D face verification Proceedings Article V: 37th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), str. 1336–1341, Mipro Opatija, Croatia, 2014. |
An experimental tattoo de-identification system for privacy protection in still images Proceedings Article V: 37th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO), str. 1288–1293, Mipro IEEE, 2014. |
Incorporating Duration Information into I-Vector-Based Speaker-Recognition Systems Proceedings Article V: Proceedings of Odyssey: The Speaker and Language Recognition Workshop, str. 241–248, 2014. |
The ijcb 2014 pasc video face and person recognition competition Proceedings Article V: Proceedings of the IEEE International Joint Conference on Biometrics (IJCB), str. 1–8, IEEE 2014. |
2013 |
Robust 3D face recognition using adapted statistical models Proceedings Article V: Proceedings of the Electrotechnical and Computer Science Conference (ERK'13), 2013. |
Zlivanje informacij za zanseljivo in robustno razpoznavanje obrazov Članek v strokovni reviji V: Electrotechnical Review, vol. 80, no. 3, str. 1-12, 2013. |
Exploiting representation plurality for robust and efficient face recognition Proceedings Article V: Proceedings of the 22nd Intenational Electrotechnical and Computer Science Conference (ERK'13), str. 121–124, Portorož, Slovenia, 2013. |
Combining 3D face representations using region covariance descriptors and statistical models Proceedings Article V: Proceedings of the IEEE International Conference on Automatic Face and Gesture Recognition and Workshops (IEEE FG), Workshop on 3D Face Biometrics, IEEE, Shanghai, China, 2013. |
Towards efficient multi-modal emotion recognition Članek v strokovni reviji V: International Journal of Advanced Robotic Systems, vol. 10, no. 53, 2013. |
Building cloud-based biometric services Članek v strokovni reviji V: Informatica, vol. 37, no. 2, str. 115, 2013. |
Smart surveillance technologies in border control Članek v strokovni reviji V: European Journal of Law and Technology, vol. 4, no. 2, 2013. |
Patch-wise low-dimensional probabilistic linear discriminant analysis for Face Recognition Proceedings Article V: 2013 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), str. 2352–2356, IEEE 2013. |
The 2013 face recognition evaluation in mobile environment Proceedings Article V: Proceedings of the IAPR International Conference on Biometrics (ICB), str. 1–7, IAPR 2013. |
Recently Deglaciated High-Altitude Soils of the Himalaya: Diverse Environments, Heterogenous Bacterial Communities and Long-Range Dust Inputs from the Upper Troposphere Članek v strokovni reviji V: PLOS ONE, vol. 8, no. 9, str. 1-10, 2013. |
Towards commoditized smart-camera design Članek v strokovni reviji V: Journal of Systems Architecture, vol. 59, no. 10, Part A, str. 847 - 858, 2013, ISSN: 1383-7621, (Smart Camera Architecture). |
2012 |
Robust 3D Face Recognition Članek v strokovni reviji V: Electrotechnical Review, vol. 79, no. 1-2, str. 1-6, 2012. |
Towards robust 3D face verification using Gaussian mixture models Članek v strokovni reviji V: International Journal of Advanced Robotic Systems, vol. 9, 2012. |
Face recognition using simplified probabilistic linear discriminant analysis Članek v strokovni reviji V: International Journal of Advanced Robotic Systems, vol. 9, 2012. |
2011 |
Photometric normalization techniques for illumination invariance Book Section V: Zhang, Yu-Jin (Ur.): Advances in Face Image Analysis: Techniques and Technologies, str. 279-300, IGI-Global, 2011. |
Principal directions of synthetic exact filters for robust real-time eye localization Proceedings Article V: Proceedings of the COST workshop on Biometrics and Identity Management (BioID), str. 180/192, Springer-Verlag, Berlin, Heidelberg, 2011. |
2010 |
Face recogniton from color images using sparse projection analysis Proceedings Article V: Proceedings of the 7th International Conference on Image Analysis and Recognition (ICIAR 2010), str. 445-453, Povoa de Varzim, Portugal, 2010. |
Adaptation of SIFT Features for Robust Face Recognition Proceedings Article V: Proceedings of the 7th International Conference on Image Analysis and Recognition (ICIAR 2010), str. 394-404, Povoa de Varzim, Portugal, 2010. |
Removing Illumination Artifacts from Face Images using the Nuisance Attribute Projection Proceedings Article V: Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP'10), str. 846-849, IEEE, Dallas, Texas, USA, 2010. |
V: Oravec, Milos (Ur.): Face Recognition, str. 215-238, In-Tech, Vienna, 2010. |
The Complete Gabor-Fisher Classifier for Robust Face Recognition Članek v strokovni reviji V: EURASIP Advances in Signal Processing, vol. 2010, str. 26, 2010. |
An evaluation of video-to-video face verification Članek v strokovni reviji V: IEEE Transactions on Information Forensics and Security, vol. 5, no. 4, str. 781–801, 2010. |
Confidence Weighted Subspace Projection Techniques for Robust Face Recognition in the Presence of Partial Occlusions Proceedings Article V: Proceedings of the International Conference on Pattern Recognition (ICPR'10), str. 1334-1338, Istanbul, Turkey, 2010. |
Multi-modal Emotion Recognition using Canonical Correlations and Acustic Features Proceedings Article V: Proceedings of the International Conference on Pattern Recognition (ICPR), str. 4133-4136, IAPR Istanbul, Turkey, 2010. |
Multi-modal Emotion Recognition based on the Decoupling of Emotion and Speaker Information Proceedings Article V: Proceedings of Text, Speech and Dialogue (TSD), str. 275-282, Springer-Verlag, Berlin, Heidelberg, 2010. |
Eye Localization using correlation filters Proceedings Article V: Proceedings of the International Conference DOGS, str. 188-191, Novi Sad, Serbia, 2010. |
DNA encoding for an efficient 'Omics processing Članek v strokovni reviji V: Computer Methods and Programs in Biomedicine, vol. 100, no. 2, str. 175 - 190, 2010, ISSN: 0169-2607. |
2009 |
Principal Gabor Filters for Face Recognition Proceedings Article V: Proceedings of the 3rd IEEE International Conference on Biometrics: Theory, Systems and Applications (BTAS'09), str. 1-6, IEEE, Washington D.C., U.S.A., 2009. |
Emotion recognition using linear transformations in combination with video Proceedings Article V: Speech and intelligence: proceedings of Interspeech 2009, str. 1967-1970, Brighton, UK, 2009. |
Nuisance Attribute Projection in the Logarithm Domain for Face Recognition under Severe Illumination Changes Proceedings Article V: Proceedings of the IEEE International Electrotechnical and Computer Science Conference (ERK'09), str. 279-281, Portorož, Slovenia, 2009. |
Face Recognition using Sparse Projection Axes Proceedings Article V: Proceedings of the IEEE International Electrotechnical and Computer Science Conference (ERK'09), str. 271-274, Portorož, Slovenia, 2009. |
A comparative assessment of appearance based feature extraction techniques and their susceptibility to image degradations in face recognition systems Proceedings Article V: Proceedings of the International Conference on Machine Learning and Pattern Recognition (ICMLPR'09), str. 326-334, Paris, France, 2009. |
A comparison of feature normalization techniques for PCA-based palmprint recognition Proceedings Article V: Proceedings of the International Conference on Mathematical Modeling (MATHMOD'09), str. 2450-2453, Viena, Austria, 2009. |
Image normalization techniques for robust face recognition Proceedings Article V: Proceedings of the International Conference on Signal Processing, Robotics and Automation (ISPRA'09), str. 155-160, Cambridge, UK, 2009. |
Hand-Geometry Device Book Section V: Li, Stan Z (Ur.): Encyclopedia of biometrics, str. 693-698, Springer-Verlag, New York, 2009. |
Gabor-based kernel-partial-least-squares discrimination features for face recognition Članek v strokovni reviji V: Informatica (Vilnius), vol. 20, no. 1, str. 115-138, 2009. |
Histogram remapping as a preprocessing step for robust face recognition Članek v strokovni reviji V: WSEAS transactions on information science and applications, vol. 6, no. 3, str. 520-529, 2009. |
Multi-modal emotional database: AvID Članek v strokovni reviji V: Informatica (Ljubljana), vol. 33, no. 1, str. 101-106, 2009. |
Using regression techniques for coping with the one-sample-size problem of face recognition Članek v strokovni reviji V: Electrotechnical Review, vol. 76, no. 1-2, str. 7-12, 2009. |
Phase-congruency features for palm-print verification Članek v strokovni reviji V: IET Signal Processing, vol. 3, no. 4, str. 258-268, 2009. |
Gaussianization of image patches for efficient palmprint recognition Članek v strokovni reviji V: Electrotechnical Review, vol. 76, no. 5, str. 245-250, 2009. |
Face Video Competition Proceedings Article V: Tistarelli, Massimo; Nixon, Mark (Ur.): Proceedings of the international Conference on Biometrics (ICB), str. 715-724, Springer-Verlag, Berlin, Heidelberg, 2009. |