Facial expression recognition on multiple manifolds

Manifold learning has been successfully applied to facial expression recognition by modeling different expressions as a smooth manifold embedded in a high dimensional space. However, the assumption of single manifold is still arguable and therefore does not necessarily guarantee the best classification accuracy. In this paper, a generalized framework for modeling and recognizing facial expressions on multiple manifolds is presented which assumes that different expressions may reside on different manifolds of possibly different dimensionalities. The intrinsic features of each expression are firstly learned separately and the genetic algorithm (GA) is then employed to obtain the nearly optimal dimensionality of each expression manifold from the classification viewpoint. Classification is performed under a newly defined criterion that is based on the minimum reconstruction error on manifolds. Extensive experiments on both the Cohn-Kanade and Feedtum databases show the effectiveness of the proposed multiple manifold based approach.     

Facial expression recognition based on shape and texture

In this paper, an efficient method for human facial expression recognition is presented. We first propose a representation model for facial expressions, namely the spatially maximum occurrence model (SMOM), which is based on the statistical characteristics of training facial images and has a powerful representation capability. Then the elastic shape-texture matching (ESTM) algorithm is used to measure the similarity between images based on the shape and texture information. By combining SMOM and ESTM, the algorithm, namely SMOM-ESTM, can achieve a higher recognition performance level. The recognition rates of the SMOM-ESTM algorithm based on the AR database and the Yale database are 94.5% and 94.7%, respectively.     

Facial expression recognition and tracking for intelligent human-robot interaction

For effective interaction between humans and socially adept, intelligent service robots, a key capability required by this class of sociable robots is the successful interpretation of visual data. In addition to crucial techniques like human face detection and recognition, an important next step for enabling intelligence and empathy within social robots is that of emotion recognition. In this paper, an automated and interactive computer vision system is investigated for human facial expression recognition and tracking based on the facial structure features and movement information. Twenty facial features are adopted since they are more informative and prominent for reducing the ambiguity during classification. An unsupervised learning algorithm, distributed locally linear embedding (DLLE), is introduced to recover the inherent properties of scattered data lying on a manifold embedded in high-dimensional input facial images. The selected person-dependent facial expression images in a video are classified using the DLLE. In addition, facial expression motion energy is introduced to describe the facial muscle’s tension during the expressions for person-independent tracking for person-independent recognition. This method takes advantage of the optical flow which tracks the feature points’ movement information. Finally, experimental results show that our approach is able to separate different expressions successfully.     

Facial expression recognition based on two-dimensional discriminant locality preserving projections

In this paper, a novel method called two-dimensional discriminant locality preserving projections (2D-DLPP) is proposed. By introducing between-class scatter constraint and label information into two-dimensional locality preserving projections (2D-LPP) algorithm, 2D-DLPP successfully finds the subspace which can best discriminate different pattern classes. So the subspace obtained by 2D-DLPP has more discriminant power than 2D-LPP, and is more suitable for recognition tasks. The proposed method was applied to facial expression recognition tasks on JAFFE and Cohn-Kanade database and compared with other three widely used two-dimensional methods: 2D-PCA, 2D-LDA and 2D-LPP. The high recognition rates show the effectiveness of the proposed algorithm.     

Facial expression recognition in dynamic sequences: An integrated approach

Automatic facial expression analysis aims to analyse human facial expressions and classify them into discrete categories. Methods based on existing work are reliant on extracting information from video sequences and employ either some form of subjective thresholding of dynamic information or attempt to identify the particular individual frames in which the expected behaviour occurs. These methods are inefficient as they require either additional subjective information, tedious manual work or fail to take advantage of the information contained in the dynamic signature from facial movements for the task of expression recognition.     

采用Adaboost算法进行面部表情识别

Adaboost是一种有效的分类器组合方法，它能够提高弱分类器的分类性能。利用Adaboost方法对面部表情进行识别，探讨了Adaboost与主成分分析法的几种结合方案。仿真结果表明这几种方案可行，且识别效果较好。     

Facial expression recognition system based on rigid and non-rigid motion separation and 3D pose estimation

This study presents a facial expression recognition system which separates the non-rigid facial expression from the rigid head rotation and estimates the 3D rigid head rotation angle in real time. The extracted trajectories of the feature points contain both rigid head motion components and non-rigid facial expression motion components. A 3D virtual face model is used to obtain accurate estimation of the head rotation angle such that the non-rigid motion components can be precisely separated to enhance the facial expression recognition performance. The separation performance of the proposed system is further improved through the use of a restoration mechanism designed to recover feature points lost during large pan rotations. Having separated the rigid and non-rigid motions, hidden Markov models (HMMs) are employed to recognize a prescribed set of facial expressions defined in terms of facial action coding system (FACS) action units (AUs).     

基于HSMM的人脸表情识别

针对表情识别中存在人脸semi-Markov models,HSMM)的人脸表情识别模型.该模型具有每个状态产生多个观察值、允许观察值缺省等特性,据此识别那些由于局部被遮挡或其它原因引起的丢失特征的人脸表情.实验结果表明,该模型提高了部分遮挡人脸的表情识别效果,同时对无遮挡人脸的表情识别也有所改善.     

基于Gabor小波变换的人脸表情识别技术研究

为了使人机交互得到更好的研究,提出了一种基于Gabor小波变换的人脸表情识别的新方法;首先对图像进行预处理以提高后续处理的准确度,预处理包括确定纯的人脸表情区域,尺寸和灰度归一化,然后对表情子区域进行Gabor小波变换,提取表情特征矢量,进而构建表情弹性图,最后用模板匹配的方法来识别图像的人脸表情;经过实验,发现Gabor小波变换提取特征时受光照影响比较小,该系统不仅具有很好的鲁棒性,并且速度快,识别率高。     

基于细菌觅食算法和支持向量机的表情识别

为正确选择应用于人脸表情识别的支持向量机相关参数,提高表情识别准确率,提出一种应用于表情识别的基于细菌觅食算法的支持向量机参数选择方法。利用细菌觅食算法,通过模拟细菌觅食行为的趋向性操作、复制操作和迁移操作对应用于表情识别的支持向量机的参数进行寻优,避免寻优陷入局部最优,实现参数优化。实验结果表明,采用该方法能够使人脸表情识别分类结果具有更高的准确率。     

基于特征块主成分分析的人脸表情识别

使用特征块主成分分析(FBPCA)对人脸表情进行特征提取,然后输入最近邻分类器得到分类结果.同时,讨论了特征脸个数在实验中的影响,总结出了识别率与特征脸数量的关系.分别在JAFFE表情库上做了训练数据包含测试数据和训练数据不包含测试数据等情况的表情识别.     

基于协作低秩分层稀疏和LC-KSVD的人脸表情识别

为了降低人脸表情识别对待识别个体的依赖程度,控制识别字典规模,增加识别准确度,提出了一种基于协作低秩和分层稀疏的表情识别字典构建方法.通过协作低秩和分层稀疏表示(C-HiSLR)有效分离与待识别个体相关部分,保留表情变化部分,并结合标签一致区分字典学习(LC-KSVD)算法,进行相应待训练表情序列的重构识别和对应类别字典的区分程度的优化学习.该方法在CK+数据集上进行验证,识别效果较一般基于稀疏表示模型算法有明显的提升.     

Static and dynamic 3D facial expression recognition: A comprehensive survey

Automatic facial expression recognition constitutes an active research field due to the latest advances in computing technology that make the user's experience a clear priority. The majority of work conducted in this area involves 2D imagery, despite the problems this presents due to inherent pose and illumination variations. In order to deal with these problems, 3D and 4D (dynamic 3D) recordings are increasingly used in expression analysis research. In this paper we survey the recent advances in 3D and 4D facial expression recognition. We discuss developments in 3D facial data acquisition and tracking, and present currently available 3D/4D face databases suitable for 3D/4D facial expressions analysis as well as the existing facial expression recognition systems that exploit either 3D or 4D data in detail. Finally, challenges that have to be addressed if 3D facial expression recognition systems are to become a part of future applications are extensively discussed.     

Unsupervised information extraction from unstructured, ungrammatical data sources on the World Wide Web

Information extraction from unstructured, ungrammatical data such as classified listings is difficult because traditional structural and grammatical extraction methods do not apply. Previous work has exploited reference sets to aid such extraction, but it did so using supervised machine learning. In this paper, we present an unsupervised approach that both selects the relevant reference set(s) automatically and then uses it for unsupervised extraction. We validate our approach with experimental results that show our unsupervised extraction is competitive with supervised machine learning approaches, including the previous supervised approach that exploits reference sets.     

Simultaneous Facial Action Tracking and Expression Recognition in the Presence of Head Motion

The recognition of facial gestures and expressions in image sequences is an important and challenging problem. Most of the existing methods adopt the following paradigm. First, facial actions/features are retrieved from the images, then the facial expression is recognized based on the retrieved temporal parameters. In contrast to this mainstream approach, this paper introduces a new approach allowing the simultaneous retrieval of facial actions and expression using a particle filter adopting multi-class dynamics that are conditioned on the expression. For each frame in the video sequence, our approach is split into two consecutive stages. In the first stage, the 3D head pose is retrieved using a deterministic registration technique based on Online Appearance Models. In the second stage, the facial actions as well as the facial expression are simultaneously retrieved using a stochastic framework based on second-order Markov chains. The proposed fast scheme is either as robust as, or more robust than existing ones in a number of respects. We describe extensive experiments and provide evaluations of performance to show the feasibility and robustness of the proposed approach.     

Searching the World Wide Web with Lycos and Infoseek

This paper evaluates the use of the Lycos and InfoSeek search tools for information discovery of the World Wide Web (WWW). It concentrates on a close comparison between the services offered by each of these tools; focusing on search interfaces and languages, collection size and content, quality and indexing issues and the increasing move towards commercialisation of tools on the WWW which are used for organising and cataloguing resources. The paper concludes that both of these search tools are able to produce results of some value when WWW searching and each has strengths and weaknesses in certain areas. Quality and indexing issues have yet to be successfully addressed by the current database creation strategies used by these tools.     

Real-time 2D+3D facial action and expression recognition

This paper presents a completely automated facial action and facial expression recognition system using 2D+3D images recorded in real-time by a structured light sensor. It is based on local feature tracking and rule-based classification of geometric, appearance and surface curvature measurements. Several experiments conducted under relatively non-controlled conditions demonstrate the accuracy and robustness of the approach.