Ce Zhan

Cryptographic Key Generation from Biometric Data Using Lattice Mapping

Crypto-biometric systems are recently emerging as an effective process of key management to address the security weakness of conventional key release systems using pass-codes, tokens or pattern recognition based biometrics. This paper presents a lattice mapping based fuzzy commitment method for cryptographic key generation from biometric data. The proposed method not only outputs high entropy keys, but also conceals the original biometric data such that it is impossible to recover the biometric data even when the stored information in the system is open to an attacker. Simulated results have demonstrated that its authentication accuracy is comparable to the well-known k-nearest neighbour classification

A real-time facial expression recognition system for online games

Multiplayer online games (MOGs) have become increasingly popular because of the opportunity they provide for collaboration, communication, and interaction. However, compared with ordinary human communication, MOG still has several limitations, especially in communication using facial expressions. Although detailed facial animation has already been achieved in a number of MOGs, players have to use text commands to control the expressions of avatars. In this paper, we propose an automatic expression recognition system that can be integrated into an MOG to control the facial expressions of avatars. To meet the specific requirements of such a system, a number of algorithms are studied, improved, and extended. In particular, Viola and Jones face-detection method is extended to detect small-scale key facial components; and fixed facial landmarks are used to reduce the computational load with little performance degradation in the recognition accuracy.

Smoke detection in videos using Non-Redundant Local Binary Pattern-based features

This paper presents a novel and low complexity method for real-time video-based smoke detection. As a local texture operator, Non-Redundant Local Binary Pattern (NRLBP) is more discriminative and robust to illumination changes in comparison with original Local Binary Pattern (LBP), thus is employed to encode the appearance information of smoke. Non-Redundant Local Motion Binary Pattern (NRLMBP), which is computed on the difference image of consecutive frames, is introduced to capture the motion information of smoke. Experimental results show that NRLBP outperforms the original LBP in the smoke detection task. Furthermore, the combination of NRLBP and NRLMBP, which can be considered as a spatial-temporal descriptor of smoke, can lead to remarkable improvement on detection performance.

Real-time facial feature point extraction

Localization of facial feature points is an important step for many subsequent facial image analysis tasks. In this paper, we proposed a new coarse-to-fine method for extracting 20 facial feature points from image sequences. In particular, the Viola-Jones face detection method is extended to detect small-scale facial components with wide shape variations, and linear Kalman filters are used to smoothly track the feature points by handling detection errors and head rotations. The proposed method achieved higher than 90% detection rate when tested on the BioID face database and the FG-NET facial expression database. Moreover, our method shows robust performance against the variation of face resolutions and facial expressions.

Face recognition from single sample based on human face perception

Although research show that human recognition performance for unfamiliar faces is relatively poor, when the sample is always available for analysis and becomes ”familiar”, people are able to recognize a previous unknown face from single sample. In this paper, a method is proposed to deal with the one sample per person face recognition problem based on the process how unfamiliar faces become familiar to people. Particularly, quantized local features which learnt from generic face dataset are used in the proposed method to mimic the prototype effect of human face recognition. Furthermore, a landmark-based scheme is introduced to quantify the distinctiveness of each facial component for the sample face, then the difference between the sample and the average face is emphasized by weighting face regions according to the gained distinctiveness. The experiments on ORL and FERET face databases demonstrate the efficiency of the proposed method.

Age estimation based on extended non-negative matrix factorization

Previous studies suggested that local appearance-based methods are more efficient than geometric-based and holistic methods for age estimation. This is mainly due to the fact that age information are usually encoded by the local features such as wrinkles and skin texture on the forehead or at the eye corners. However, the variations of theses features caused by other factors such as identity, expression, pose and lighting may be larger than that caused by aging. Thus, one of the key challenges of age estimation lies in constructing a feature space that could successfully recovers age information while ignoring other sources of variations. In this paper, non-negative matrix factorization (NMF) is extended to learn a localized non-overlapping subspace representation for age estimation. To emphasize the appearance variation in aging, one individual extended NMF subspace is learned for each age or age group. The age or age group of a given face image is then estimated based on its reconstruction error after being projected into the learned age subspaces. Furthermore, a coarse to fine scheme is employed for exact age estimation, so that the age is estimated within the pre-classified age groups. Cross-database tests are conducted using FG-NET and MORPH databases to evaluate the proposed method. Experimental results have demonstrated the efficacy of the method.

Measuring the degree of face familiarity based on extended NMF

Getting familiar with a face is an important cognitive process in human perception of faces, but little study has been reported on how to objectively measure the degree of familiarity. In this article, a method is proposed to quantitatively measure the familiarity of a face with respect to a set of reference faces that have been seen previously. The proposed method models the context-free and context-dependent forms of familiarity suggested by psychological studies and accounts for the key factors, namely exposure frequency, exposure intensity and similar exposure, that affect human perception of face familiarity. Specifically, the method divides the reference set into nonexclusive groups and measures the familiarity of a given face by aggregating the similarities of the face to the individual groups. In addition, the nonnegative matrix factorization (NMF) is extended in this paper to learn a compact and localized subspace representation for measuring the similarities of the face with respect to the individual groups. The proposed method has been evaluated through experiments that follow the protocols commonly used in psychological studies and has been compared with subjective evaluation. Results have shown that the proposed measurement is highly consistent with the subjective judgment of face familiarity. Moreover, a face recognition method is devised using the concept of face familiarity and the results on the standard FERET evaluation protocols have further verified the efficacy of the proposed familiarity measurement.

Finding distinctive facial areas for face recognition

One of the key issues for local appearance based face recognition methods is that how to find the most discriminative facial areas. Most of the existing methods take the assumption that anatomical facial components, such as the eyes, nose, and mouth, are the most useful areas for recognition. Other more elaborate methods locate the most salient parts within the face according to a pre-specified criterion. In this paper, a novel method is proposed to identify the discriminative facial areas for face recognition. Unlike the existing methods that only analyze the given face, the proposed method identifies the distinctive areas of each individuals face by its comparison to the general population. In particular, non-negative matrix factorization (NMF) is extended to learn a localized non-overlapping subspace representation of the facial patterns from a generic face image database. In the learned subspace, the degree of distinctiveness for any facial area is measured depends on the probability of this area is belong to a general face. For evaluation, the proposed method is tested on exaggerated face images and applied in exiting face recognition systems. Experimental results demonstrate the efficiency of the proposed method.

Measuring face familiarity and its application to face recognition

The familiarity of faces is one of the key factors that come into play during human face analysis. However, there is very little research that studies face familiarity. In this paper, two methods are proposed to quantitatively measure the degree of familiarity of a face with respect to a known set. The methods are in accordance with the psychological study. In particular, non-negative matrix factorization (NMF) is extended to learn a localized non-overlapping subspace representation of commonly experienced facial patterns from known faces. The familiarity of a given face is then measured based on its reconstruction error after being projected into the learned extended NMF subspaces. A subjective study involving 50 subjects indicates the proposed familiarity measurement is in line with human judgments. Furthermore, the familiarity vector generated during the measuring process is employed for face recognition. Experiments based on the standard FERET evaluation protocol demonstrates the efficacy of the familiarity based representation for face recognition.

Head pose estimation based on extended non-negative matrix factorization

One popular solution to head pose estimation is to formulate it as a pattern classification problem, and treat the holistic facial appearance as the input to classifiers. However, since the face appearance contains all kinds of information, the variation caused by other factors such as identity, expression and lighting may be larger than that caused by different head poses. Thus, the key challenge of these appearance based methods lies in constructing a feature subspace that could successfully recovers head pose while ignoring other sources of image variation. In this paper, following the intuition of combining parts to form a whole face, non-negative matrix factorization (NMF) is extended to learn a localized non-overlapping subspace representation for head pose estimation. To emphasize the appearance variation in head poses, one individual extended NMF subspace is learned for each pose. The head pose of a given face image is then estimated based on its reconstruction error after being projected into the learned pose subspaces. Experiments based on benchmark face database demonstrate the efficiency of the proposed method.