nils-herrmann/clean_scirepeval huggingface dataset:
Fast kernel SVM training via support vector identification

Training kernel SVM on large datasets suffers from high computational complexity and requires a large amount of memory. However, a desirable property of SVM is that its decision function is solely determined by the support vectors, a subset of training examples with non-vanishing weights. This motivates a novel efficient algorithm for training kernel SVM via support vector identification. The efficient training algorithm involves two steps. In the first step, we randomly sample the training data without replacement several times, each time a small subset of training data is sampled. Then a kernel SVM is trained on each subset, and the resulting kernel SVM models are used to identify the support vectors on the margin. In the second step, an optimization problem is solved to estimate the Lagrange multipliers corresponding to these support vectors. After obtaining the support vectors and Lagrange multipliers, we can approximate the decision function of kernel SVM. Due to the cubic complexity of standard kernel SVM training algorithm, training many kernel SVMs on small subsets of training data is much more efficient than training a single kernel SVM on the whole training data especially for large datasets. Therefore, our algorithm has better scalability than kernel SVM. Besides, training SVMs on each subset can be done independently, and hence our algorithm can be easily parallelized for further speedup. Since our algorithm only identifies the support vectors on the margin, it produces less number of support vectors as compared to that produced by standard kernel SVM. This makes our algorithm more efficient in prediction too. Experimental results show that our method outperforms state-of-the-art methods and achieves performance on par with the kernel SVM albeit with much improved efficiency.
Action Recognition Using Nonnegative Action Component Representation and Sparse Basis Selection

In this paper, we propose using high-level action units to represent human actions in videos and, based on such units, a novel sparse model is developed for human action recognition. There are three interconnected components in our approach. First, we propose a new context-aware spatial-temporal descriptor, named locally weighted word context, to improve the discriminability of the traditionally used local spatial-temporal descriptors. Second, from the statistics of the context-aware descriptors, we learn action units using the graph regularized nonnegative matrix factorization, which leads to a part-based representation and encodes the geometrical information. These units effectively bridge the semantic gap in action recognition. Third, we propose a sparse model based on a joint l2,1-norm to preserve the representative items and suppress noise in the action units. Intuitively, when learning the dictionary for action representation, the sparse model captures the fact that actions from the same class share similar units. The proposed approach is evaluated on several publicly available data sets. The experimental results and analysis clearly demonstrate the effectiveness of the proposed approach.
Single and Multiple Object Tracking Using Log-Euclidean Riemannian Subspace and Block-Division Appearance Model

Object appearance modeling is crucial for tracking objects, especially in videos captured by nonstationary cameras and for reasoning about occlusions between multiple moving objects. Based on the log-euclidean Riemannian metric on symmetric positive definite matrices, we propose an incremental log-euclidean Riemannian subspace learning algorithm in which covariance matrices of image features are mapped into a vector space with the log-euclidean Riemannian metric. Based on the subspace learning algorithm, we develop a log-euclidean block-division appearance model which captures both the global and local spatial layout information about object appearances. Single object tracking and multi-object tracking with occlusion reasoning are then achieved by particle filtering-based Bayesian state inference. During tracking, incremental updating of the log-euclidean block-division appearance model captures changes in object appearance. For multi-object tracking, the appearance models of the objects can be updated even in the presence of occlusions. Experimental results demonstrate that the proposed tracking algorithm obtains more accurate results than six state-of-the-art tracking algorithms.
Mining activities using sticky multimodal dual hierarchical Dirichlet process hidden Markov model

In this paper, a new nonparametric Bayesian model called Sticky Multimodal Dual Hierarchical Dirichlet Process Hidden Markov Model (SMD-HDP-HMM) is proposed for mining activities from a collection of time series. An activity is modeled as an HMM where each state corresponds to an atomic activity. By extensively using Dirichlet Process (DP), multiple HMMs sharing a common set of states are learned and the numbers of HMMs and states are both automatically determined. Each time series is modeled to be generated by one of the HMMs such that all time series are clustered into activities. Simultaneously state sequences for time series are learned and each of them is decomposed into a sequence of atomic activities. Experimental results on KTH activity dataset demonstrate the advantage of our method.
Multi-Instance Multi-Label Learning Combining Hierarchical Context and its Application to Image Annotation

In image annotation, one image is often modeled as a bag of regions (“instances”) associated with multiple labels, which is a typical application of multi-instance multi-label learning (MIML). Although lots of research has shown that the interplay embedded among instances and labels can largely boost the image annotation accuracy, most existing MIML methods consider none or partial context cues. In this paper, we propose a novel context-aware MIML model to integrate the instance context and label context into a general framework. Specially, the instance context is constructed with multiple graphs, while the label context is built up through a linear combination of several common latent conceptions that link low level features and high level semantic labels. Comparison with other leading methods on several benchmark datasets in terms of image annotation shows that our proposed method can get better performance than the state-of-the-art approaches.
Robust Object Tracking with Online Multi-lifespan Dictionary Learning

Recently, sparse representation has been introduced for robust object tracking. By representing the object sparsely, i.e., using only a few templates via L1-norm minimization, these so-called L1-trackers exhibit promising tracking results. In this work, we address the object template building and updating problem in these L1-tracking approaches, which has not been fully studied. We propose to perform template updating, in a new perspective, as an online incremental dictionary learning problem, which is efficiently solved through an online optimization procedure. To guarantee the robustness and adaptability of the tracking algorithm, we also propose to build a multi-lifespan dictionary model. By building target dictionaries of different life spans, effective object observations can be obtained to deal with the well-known drifting problem in tracking and thus improve the tracking accuracy. We derive effective observation models both generatively and discriminatively based on the online multi-lifespan dictionary learning model and deploy them to the Bayesian sequential estimation framework to perform tracking. The proposed approach has been extensively evaluated on ten challenging video sequences. Experimental results demonstrate the effectiveness of the online learned templates, as well as the state-of-the-art tracking performance of the proposed approach.
A Novel Web Page Filtering System by Combining Texts and Images

With the rapid development of the Internet, people benefit much from the sharing of information. Meanwhile, the WWW era is a double-edged sword which spreads harmful and erotic content widely. In this paper, a new statistical approach has been exploited by combining the results of two or more different classification methods using our filtering system. We first briefly introduce the classification of discrete texts, continuous texts and images separately, and then describe the specific way we have been exploring to merge the text and image classification result. Also there is a section illustrating our system framework. Finally we assess our method by demonstrating the experimental results and comparing it to some common-used filtering methods
Learning to predict the perceived visual quality of photos

Visual quality (VisQ) representation is a fundamental step in the learning of a VisQ prediction model for photos. It not only reflects how we understand VisQ but also determines the label type. Existing studies apply a scalar value (i.e., a categorical label or a score) to represent VisQ. As VisQ is a subjective property, only a scalar value is insufficient to represent human's perceived VisQ of a photo. This study represents VisQ by a distribution on pre-defined ordinal basic ratings in order to capture the subjectivity of VisQ better. When using the new representation, the label type is structural instead of scalar. Conventional learning algorithms cannot be directly applied in model learning. Meanwhile, for many photos, the numbers of users involved in the evaluation are limited, making some labels unreliable. In this study, a new algorithm called support vector distribution regression (SVDR) is presented to deal with the structural output learning. Two independent learning strategies (reliability-sensitive learning and label refinement) are proposed to alleviate the difficulty of insufficient involved users for rating. Combining SVDR with the two learning strategies, two separate structural-output regression algorithms (i.e., reliability-sensitive SVDR and label refinement-based SVDR) are produced. Experimental results demonstrate the effectiveness of our introduced learning strategies and learning algorithms.
Learning A Superpixel-Driven Speed Function for Level Set Tracking

A key problem in level set tracking is to construct a discriminative speed function for effective contour evolution. In this paper, we propose a level set tracking method based on a discriminative speed function, which produces a superpixel-driven force for effective level set evolution. Based on kernel density estimation and metric learning, the speed function is capable of effectively encoding the discriminative information on object appearance within a feasible metric space. Furthermore, we introduce adaptive object shape modeling into the level set evolution process, which leads to the tracking robustness in complex scenarios. To ensure the efficiency of adaptive object shape modeling, we develop a simple but efficient weighted non-negative matrix factorization method that can online learn an object shape dictionary. Experimental results on a number of challenging video sequences demonstrate the effectiveness and robustness of the proposed tracking method.
Adaptive cooperative tracking based on multi-graph embedding and Markov Random Field

Appearance model is of fundamental importance in a tracking algorithm. In this paper, we propose a new tracking method based on a cooperative object appearance model which incorporates both the discriminative and generative information. We represent the discriminative information with graph embedding (GE). To represent the local object appearance effectively, we divide the object and nearby background into patches. As the discriminative conditions around the 4 object boundaries are different, we divide the patches into 4 groups and perform GE for each group. Markov Random Filed (MRF) is designed to represent the generative information. We propose a novel MRF based method which not only considers the single patch's appearance but also the appearance relations between neighbor patches (not the relations between neighbor patches' states). The proposed cooperative appearance model can represent the object appearance's variation effectively and meanwhile discriminate the object from background robustly. Experimental results on challenging test sequences demonstrated the effectiveness of our method.
A Coarse-to-Fine Strategy for Vehicle Motion Trajectory Clustering

High-level semantic understanding of vehicle motion behaviors is often based on vehicle motion trajectory clustering. In this paper, we propose an effective trajectory clustering framework in which a coarse-to-fine strategy is taken. Our framework consists of four stages: trajectory smoothing, feature extraction, trajectory coarse clustering and trajectory fine clustering. Wavelet decomposition is imposed on raw trajectories to reduce noise in the trajectory smoothing stage. Besides the commonly used positional feature, a novel feature called trajectory directional histogram is proposed to describe the statistic directional distribution of a trajectory in the feature extraction stage. Both coarse clustering and fine clustering are based on a novel graph-theoretic clustering algorithm called dominant-set clustering, but they deal with different trajectory features. Experiments in our pre-labeled trajectory database demonstrate that the proposed trajectory clustering framework possesses a very high accuracy
Load-balanced locality-sensitive hashing: A new method for efficient near duplicate image detection

Locality-Sensitive Hashing (LSH) is a mainstream method for the Near Duplicate Image Detection (NDID) problem. Previous LSH based methods, however, do not have a principled way to make the indexing structure generate the buckets of similar sizes, which will inevitably degrade the detection effectiveness and efficiency. In this work, we propose a Load-Balanced Locality-Sensitive Hashing (LBLSH) method with a new indexing structure to produce load-balanced buckets for the hashing process. As proved in the paper, the proposed LBLSH can guarantee load-balanced buckets in the hashing process and significantly reduce the query time and the storage space. Based on the proposed LBLSH method, we design an effective and feasible algorithm for the NDID problem. Extensive experiments on two benchmark datasets demonstrate the effectiveness and efficiency of our method.
Dominant Sets-Based Action Recognition using Image Sequence Matching

Action recognition is one of the most active research fields in computer vision. In this paper, we propose a novel method for classifying human actions in a series of image sequences containing certain actions. Human action in image sequences can be recognized by a time-varying contour of human body. We first extract shape context of each contour to form the feature space. Then the dominant sets approach is used for feature clustering and classification to obtain the labeled sequences. Finally, we use a smoothing algorithm upon the labeled sequences to recognize human actions. The proposed dominant sets-based approach has been tested in comparison to three classical methods: K-means, mean shift, and fuzzy-C-mean. Experimental results demonstrate that the dominant sets-based approach achieves the best recognition performance. Moreover, our method is robust to non-rigid deformations, significant scale changes, high action irregularities, and low quality video.
Corner Detection of Contour Images using Spectral Clustering

Corner detection plays an important role in object recognition and motion analysis. In this paper, we propose a hierarchical corner detection framework based on spectral clustering (SC). The framework consists of three stages: contour smoothing, corner cell extraction and corner localization. In the contour smoothing stage, wavelet decomposition is imposed on the raw contour to reduce noise. In the corner cell extraction stage, several atomic corner cells are obtained by SC. In the corner localization stage, the corner points of each corner cell are located by the corner locator based on the kernel-weighted cosine curvature measure. Experimental results demonstrate the superiority of our framework.
Towards Robust and Accurate Multi-View and Partially-Occluded Face Alignment

Face alignment acts as an important task in computer vision. Regression-based methods currently dominate the approach to solving this problem, which generally employ a series of mapping functions from the face appearance to iteratively update the face shape hypothesis. One keypoint here is thus how to perform the regression procedure. In this work, we formulate this regression procedure as a sparse coding problem. We learn two relational dictionaries, one for the face appearance and the other one for the face shape, with coupled reconstruction coefficient to capture their underlying relationships. To deploy this model for face alignment, we derive the relational dictionaries in a stage-wised manner to perform close-loop refinement of themselves, i.e., the face appearance dictionary is first learned from the face shape dictionary and then used to update the face shape hypothesis, and the updated face shape dictionary from the shape hypothesis is in return used to refine the face appearance dictionary. To improve the model accuracy, we extend this model hierarchically from the whole face shape to face part shapes, thus both the global and local view variations of a face are captured. To locate facial landmarks under occlusions, we further introduce an occlusion dictionary into the face appearance dictionary to recover face shape from partially occluded face appearance. The occlusion dictionary is learned in a data driven manner from background images to represent a set of elemental occlusion patterns, a sparse combination of which models various practical partial face occlusions. By integrating all these technical innovations, we obtain a robust and accurate approach to locate facial landmarks under different face views and possibly severe occlusions for face images in the wild. Extensive experimental analyses and evaluations on different benchmark datasets, as well as two new datasets built by ourselves, have demonstrated the robustness and accuracy of our proposed model, especially for face images with large view variations and/or severe occlusions.
Multimodal Web Aesthetics Assessment Based on Structural SVM and Multitask Fusion Learning

The overall visual attributes (e.g., aesthetics) of Web pages significantly influence user experience. A beautiful and well laid out Web page greatly facilitates user access and enhances the browsing experience. In this paper, a new method is proposed to learn an assessment model for the (visual) aesthetics of Web pages. First, multimodal features (structural, local visual, global visual, and functional) of a Web page that are known to significantly affect the aesthetics of a Web page are extracted to construct a feature vector. Second, the interuser disagreement of aesthetics is analyzed and novel aesthetic representations are obtained from the multiuser ratings of a page. A structural learning algorithm is proposed for the new aesthetic representations. Third, as a Web page's functional purpose also affects the perceived aesthetics, we divide Web pages into different types using functional features, and a soft multitask fusion learning strategy is introduced to train assessment models for pages with functional purposes. Experimental results show the effectiveness of our method: 1) the combination of structural, local, and global visual features outperforms existing state-of-the-art Web aesthetic features; 2) the proposed structural learning algorithm achieves good results for the new aesthetic representations; and 3) the proposed soft multitask fusion learning strategy improves the performances of aesthetics assessment models.
Robust visual tracking via transfer learning

In this paper, we propose a boosting based tracking framework using transfer learning. To deal with complex appearance variations, the proposed tracking framework tries to utilize discriminative information from previous frames to conduct the tracking task in the current frame, and thus transfers some prior knowledge from the previous source data domain to the current target data domain, resulting in a high discriminative tracker for distinguishing the object from the background. The proposed tracking system has been tested on several challenging sequences. Experimental results demonstrate the effectiveness of the proposed tracking framework.
Adaptive Distributed Intrusion Detection Using Parametric Model

Due to the increasing demands for network security, distributed intrusion detection has become a hot research topic in computer science. However, the design and maintenance of the intrusion detection system (IDS) is still a challenging task due to its dynamic, scalability, and privacy properties. In this paper, we propose a distributed IDS framework which consists of the individual and global models. Specifically, the individual model for the local unit derives from Gaussian Mixture Model based on online Adaboost algorithm, while the global model is constructed through the PSO-SVM fusion algorithm. Experimental results demonstrate that our approach can achieve a good detection performance while being trained online and consuming little traffic to communicate between local units.
Horror movie scene recognition based on emotional perception

The number of video clips available online is growing at a tremendous pace. Meanwhile, the video scenes of pornography, violence and horror permeate the whole Web. Horror videos, whose threat to children's health is no less than pornographic video, are sometimes neglected by existing Web filtering tools. Consequently, an effective horror video filtering tool is necessary for preventing children from accessing these horror videos. In this paper, by introducing color emotion and color harmony theories, we propose a horror video scene recognition algorithm. Firstly, the video scenes are decomposed into a set of shots. Then we extract the visual features, audio features and color emotion features of each shot. Finally, by combining the three features, the horror video scenes are recognized by the Support Vector Machine (SVM) classifier. According to the experimental results on diverse video scenes, the proposed scheme based on the emotional perception could deal effectively with the horror video scene recognition and promising results are achieved.
Graph Embedding Based Semi-supervised Discriminative Tracker

Recently, constructing a good graph to represent data structures is widely used in machine learning based applications. Some existing trackers have adopted graph construction based classifiers for tracking. However, their graph structures are not effective to characterize the inter-class separability and multi-model sample distribution, both of which are very important to successful tracking. In this paper, we propose to use a new graph structure to improve tracking performance without the assistance of learning object subspace generatively as previous work did. Meanwhile, considering the test samples deviate from the distribution of the training samples in tracking applications, we formulate the discriminative learning process, to avoid over fitting, in a semi-supervised fashion as L1-graph based regularizer. In addition, a non-linear variant is extended to adapt to multi-modal sample distribution. Experimental results demonstrate the superior properties of the proposed tracker.