IEEE Transactions on Systems Man and Cybernetics Part B-Cybernetics最新文献

The success of generative models for online signature verification has motivated many research works on this topic. These systems may use hidden Markov models (HMMs) in two different modes: user-specific HMM (US-HMM) and user-adapted universal background models (UBMs) (UA-UBMs). Verification scores can be obtained from likelihood ratios and a distance measure on the Viterbi decoded state sequences. This paper analyzes several factors that can modify the behavior of these systems and which have not been deeply studied yet. First, we study the influence of the feature set choice, paying special attention to the role of dynamic information order, suitability of feature sets on each kind of generative model-based system, and the importance of inclination angles and pressure. Moreover, this analysis is also extended to the influence of the HMM complexity in the performance of the different approaches. For this study, a set of experiments is performed on the publicly available MCYT-100 database using only skilled forgeries. These experiments provide interesting outcomes. First, the Viterbi path evidences a notable stability for most of the feature sets and systems. Second, in the case of US-HMM systems, likelihood evidence obtains better results when lowest order dynamics are included in the feature set, while likelihood ratio obtains better results in UA-UBM systems when lowest dynamics are not included in the feature set. Finally, US-HMM and UA-UBM systems can be used together for improved verification performance by fusing at the score level the Viterbi path information from the US-HMM system and the likelihood ratio evidence from the UA-UBM system. Additional comparisons to other state-of-the-art systems, from the ESRA 2011 signature evaluation contest, are also reported, reinforcing the high performance of the systems and the generality of the experimental results described in this paper.

This paper presents our response to the first international challenge on facial emotion recognition and analysis. We propose to combine different types of features to automatically detect action units (AUs) in facial images. We use one multikernel support vector machine (SVM) for each AU we want to detect. The first kernel matrix is computed using local Gabor binary pattern histograms and a histogram intersection kernel. The second kernel matrix is computed from active appearance model coefficients and a radial basis function kernel. During the training step, we combine these two types of features using the recently proposed SimpleMKL algorithm. SVM outputs are then averaged to exploit temporal information in the sequence. To evaluate our system, we perform deep experimentation on several key issues: influence of features and kernel function in histogram-based SVM approaches, influence of spatially independent information versus geometric local appearance information and benefits of combining both, sensitivity to training data, and interest of temporal context adaptation. We also compare our results with those of the other participants and try to explain why our method had the best performance during the facial expression recognition and analysis challenge.

An important step in the identification of cellular automata (CA) is to detect the correct neighborhood before parameter estimation. Many authors have suggested procedures based on the removal of redundant neighbors from a very large initial neighborhood one by one to find the real model, but this often induces ill conditioning and overfitting. This is true particularly for a large initial neighborhood where there are few significant terms, and this will be demonstrated by an example in this paper. By introducing a new criteria and three new techniques, this paper proposes a new adaptive fast CA orthogonal-least-square (Adaptive-FCA-OLS) algorithm, which cannot only adaptively search for the correct neighborhood without any preset tolerance but can also considerably reduce the computational complexity and memory usage. Several numerical examples demonstrate that the Adaptive-FCA-OLS algorithm has better robustness to noise and to the size of the initial neighborhood than other recently developed neighborhood detection methods in the identification of binary CA.

Web prediction is a classification problem in which we attempt to predict the next set of Web pages that a user may visit based on the knowledge of the previously visited pages. Predicting user's behavior while serving the Internet can be applied effectively in various critical applications. Such application has traditional tradeoffs between modeling complexity and prediction accuracy. In this paper, we analyze and study Markov model and all- Kth Markov model in Web prediction. We propose a new modified Markov model to alleviate the issue of scalability in the number of paths. In addition, we present a new two-tier prediction framework that creates an example classifier EC, based on the training examples and the generated classifiers. We show that such framework can improve the prediction time without compromising prediction accuracy. We have used standard benchmark data sets to analyze, compare, and demonstrate the effectiveness of our techniques using variations of Markov models and association rule mining. Our experiments show the effectiveness of our modified Markov model in reducing the number of paths without compromising accuracy. Additionally, the results support our analysis conclusions that accuracy improves with higher orders of all- Kth model.

This paper addresses the problem of visual control of a set of mobile robots. In our framework, the perception system consists of an uncalibrated flying camera performing an unknown general motion. The robots are assumed to undergo planar motion considering nonholonomic constraints. The goal of the control task is to drive the multirobot system to a desired rendezvous configuration relying solely on visual information given by the flying camera. The desired multirobot configuration is defined with an image of the set of robots in that configuration without any additional information. We propose a homography-based framework relying on the homography induced by the multirobot system that gives a desired homography to be used to define the reference target, and a new image-based control law that drives the robots to the desired configuration by imposing a rigidity constraint. This paper extends our previous work, and the main contributions are that the motion constraints on the flying camera are removed, the control law is improved by reducing the number of required steps, the stability of the new control law is proved, and real experiments are provided to validate the proposal.

This paper investigates the chaotic characteristics in the dynamics of an aggregating swarm model. The range of the parameters of the swarm model is determined for which chaos exists in the dynamics. The trajectories of the individuals are simulated, and the stable, limit cyclic, and chaotic behaviors are demonstrated. The existence of chaos in the swarm is determined by the maximum Lyapunov exponent. The computer simulation supports the results obtained by theoretical analysis.

Automatic facial expression recognition has been an active topic in computer science for over two decades, in particular facial action coding system action unit (AU) detection and classification of a number of discrete emotion states from facial expressive imagery. Standardization and comparability have received some attention; for instance, there exist a number of commonly used facial expression databases. However, lack of a commonly accepted evaluation protocol and, typically, lack of sufficient details needed to reproduce the reported individual results make it difficult to compare systems. This, in turn, hinders the progress of the field. A periodical challenge in facial expression recognition would allow such a comparison on a level playing field. It would provide an insight on how far the field has come and would allow researchers to identify new goals, challenges, and targets. This paper presents a meta-analysis of the first such challenge in automatic recognition of facial expressions, held during the IEEE conference on Face and Gesture Recognition 2011. It details the challenge data, evaluation protocol, and the results attained in two subchallenges: AU detection and classification of facial expression imagery in terms of a number of discrete emotion categories. We also summarize the lessons learned and reflect on the future of the field of facial expression recognition in general and on possible future challenges in particular.

This paper presents a unified view of interestingness measures for interesting pattern discovery. Specifically, we first provide three necessary conditions for interestingness measures being used for association pattern discovery. Then, we reveal one desirable property for interestingness measures: the support-ascending conditional antimonotone property (SA-CAMP). Along this line, we prove that the measures possessing SA-CAMP are suitable for pattern discovery if the itemset-traversal structure is defined by a support-ascending set enumeration tree. In addition, we provide a thorough study on the family of the generalized mean (GM) measure and show their appealing properties, which are exploited for developing the GMiner algorithm for finding interesting association patterns. Finally, experimental results show that GMiner can efficiently identify interesting patterns based on SA-CAMP of the GM measure, even at an extremely low level of support.

This paper proposes a new video face recognition (FR) method that is designed for significantly improving FR via adaptive fusion of multiple face features (belonging to the same subject) acquired from a face sequence of video frames. In this paper, we derive an upper bound for recognition error arising from the proposed weighted feature fusion to justify theoretically its effectiveness for recognition from videos. In addition, in order to compute the optimal weights of face features to be fused, we develop a novel weight determination solution based on fuzzy membership function and quality measurement for face images. Using four public video databases, the effectiveness of the proposed method has been successfully evaluated under the conditions that are similar to those in real-world video FR applications. Furthermore, our method is simple and straightforward to implement.

Applications of the simulation of adult aging effects are widespread nowadays, whereas the difficulties in certain aspects restrict its development. In this paper, a method is proposed for simulating adult facial aging effects by means of super-resolution. Accounting for the nature of multimodalities in the face image set, multilinear algebra is introduced to represent and process the whole image set in tensor space. To ameliorate the aging simulation results generated by merely the super-resolution method, we further adopt active appearance models to reduce the blurring effects of the results through adding normalization of the faces and postprocessing to the algorithm. To evaluate our aging simulation method, the aged faces obtained are compared with the ground-truth face images of the same individuals and also assessed by several volunteers mainly from two perspectives: the aged faces' perceived age and their preservation effects of the original identities of subjects in the test images. Additionally, objective experiments based on an automatic age estimator and a face recognition method using eigenfaces are also conducted as another way of the evaluation.