Given a set of images with the number of cameras providing those images unknown, how to blindly identify the sources of the images has been a critical problem in digital forensics. Although state-of-the-art methods have achieved impressive results, they have failed at suppressing outliers. When they deal with a noisy dataset, the performance is significantly degraded. To address this issue, we propose an optimization approach with sparsity constraints to simultaneously handle the how-many subproblem (i.e., the number of cameras) and the which-from-which subproblem (i.e., the image–camera relationship). In our approach, we first formulate the blind camera source clustering as a row-sparsity optimization problem, in which the representation errors are minimized and the outliers caused by noisy features are suppressed. Then, a new two-stage refinement method based on inter- and the intra-class differences is proposed to achieve a more accurate estimation of the number of cameras. Because strong sparsity constraints have been adopted and the interactive relationship among data points can be fully explored to distinguish the images originated from different cameras, the proposed method can effectively handle outliers. Extensive experiments on the popular Dresden dataset show that the proposed method outperforms existing methods in both identification accuracy and efficiency.

It is a great challenge to develop an effective appearance model for robust visual tracking due to various interfering factors, such as pose change, occlusion, background clutter etc. More and more visual tracking methods tend to exploit the local appearance model to deal with the above challenges. In this study, the authors present a simple yet effective weighted structural local sparse appearance model, which can better describe the target appearance information through patch‐based generative weight. To further improve the robustness of tracking, they implement this appearance model on two‐scale patches. The two derived appearance models are then combined to form a collaborative model to play their advantages. Extensive experiments on the tracking benchmark dataset show that the proposed method performs favourably against several state‐of‐the‐art methods.

In this paper, we develop a new low-rank matrix recovery algorithm for image denoising. We incorporate the total variation (TV) norm and the pixel range constraint into the existing reweighted low-rank matrix analysis to achieve structural smoothness and to significantly improve quality in the recovered image. Our proposed mathematical formulation of the low-rank matrix recovery problem combines the nuclear norm, TV norm, and norm, thereby allowing us to exploit the low-rank property of natural images, enhance the structural smoothness, and detect and remove large sparse noise. Using the iterative alternating direction and fast gradient projection methods, we develop an algorithm to solve the proposed challenging non-convex optimization problem. We conduct extensive performance evaluations on single-image denoising, hyper-spectral image denoising, and video background modeling from corrupted images. Our experimental results demonstrate that the proposed method outperforms the state-of-the-art low-rank matrix recovery methods, particularly for large random noise. For example, when the density of random sparse noise is 30%, for single-image denoising, our proposed method is able to improve the quality of the restored image by up to 4.21 dB over existing methods.

Facing a large number of unlabeled data and a small number of labeled data, semisupervised sparse feature selection has received increasing attention in recent years. However, most semisupervised feature selection algorithms are developed for single-view data and cannot naturally handle multiview data. Moreover, most existing semisupervised sparse feature selection methods are based on Laplacian regularization, which is a lack of extrapolating power. To overcome the above-mentioned drawbacks, we present a multiview Hessian semi-supervised sparse feature selection (MHSFS) framework in this paper. MHSFS can directly accomplish multiview sparse feature selection by exploiting multiview learning to reveal and leverage the correlated and complemental information among different views. In addition, MHSFS can achieve better performance based on Hessian regularization, which favors functions whose values linearly vary with respect to geodesic distance and preserves the local manifold structure well. A simple yet efficient iterative method is proposed to solve the objective function, followed by convergence analysis. We apply the proposed method into different multimedia analysis tasks, such as image annotation, video concept detection, and 3D motion analysis. The results show that MHSFS outperforms the state-of-the-art sparse feature selection methods and achieves good performance.

Low-rank approximation has been successfully used for dimensionality reduction, image noise removal, and image restoration. In existing work, input images are often reshaped to a matrix of vectors before low-rank decomposition. It has been observed that this procedure will destroy the inherent two-dimensional correlation within images. To address this issue, the generalized low-rank approximation of matrices (GLRAM) method has been recently developed, which is able to perform low-rank decomposition of multiple matrices directly without the need for vector reshaping. In this paper, we propose a new robust generalized low-rank matrices decomposition method, which further extends the existing GLRAM method by incorporating rank minimization into the decomposition process. Specifically, our method aims to minimize the sum of nuclear norms and l1-norms. We develop a new optimization method, called alternating direction matrices tri-factorization method, to solve the minimization problem. We mathematically prove the convergence of the proposed algorithm. Our extensive experimental results demonstrate that our method significantly outperforms existing GLRAM methods.

In this paper, we propose a robust collaborative tracking algorithm based on interest points detection and template matching in sparse representation framework. In the proposed tracker, the target dictionary and the candidate dictionary are constructed with the patches around interest points of the previous frame and the current frame, respectively. The correspondence between target points and candidate points is computed by solving an Li minimization problem. Only the mutually matched target and candidate point pairs are selected, and the displacements of them are measured to generate the candidate targets in current frame. To find the best one among all candidate targets, each of them is sparsely represented by target templates given as benchmarks in initial frame. The candidate target with the smallest projection error produces the final tracking result. The experimental results show that the proposed tracker is superior to the state-of-the-art methods remarkably with respect to the tracking accuracy.

Almost all existing state-of-the-art pedestrian detection methods use combination of hand-crafted features, which cannot well handle the particular challenges in real-world situation. In this paper, we take advantage of Regions with Convolution Neural Networks features (R-CNN) to extract more robust pedestrian features for effective pedestrian detection in complicated environments. To further improve the performance: 1) we propose a Region Proposal Fusion algorithm to get effective region proposals since after careful observation, we found that the quality of region proposals is crucially important for detection performance. 2) we exploit a pedestrian detection expansion method based on image retrieval with color moment features due to R-CNN's requirements of large number of training samples to avoid overfitting. Consequently, the final average miss rate is greatly reduced to 23% in the INRIA pedestrian detection dataset, which is much (23%) lower than that of original HOG (46%).

With the proliferation of large-scale community-contributed images, hashing-based approximate nearest neighbor search in huge databases has aroused considerable interest from the fields of computer vision and multimedia in recent years because of its computational and memory efficiency. In this paper, we propose a novel hashing method named neighborhood discriminant hashing (NDH) (for short) to implement approximate similarity search. Different from the previous work, we propose to learn a discriminant hashing function by exploiting local discriminative information, i.e., the labels of a sample can be inherited from the neighbor samples it selects. The hashing function is expected to be orthogonal to avoid redundancy in the learned hashing bits as much as possible, while an information theoretic regularization is jointly exploited using maximum entropy principle. As a consequence, the learned hashing function is compact and nonredundant among bits, while each bit is highly informative. Extensive experiments are carried out on four publicly available data sets and the comparison results demonstrate the outperforming performance of the proposed NDH method over state-of-the-art hashing techniques.

Semi-supervised sparse feature selection, which can exploit the small number labeled data and large number unlabeled data simultaneously, has become an important technique in many applications on large-scale web image owing to its high efficiency and effectiveness. Recently, graph Laplacian-based semi-supervised sparse feature selection has obtained considerable attention, but it suffers with only few labeled data because Laplacian regularization is short of extrapolating power. In this paper we propose a novel semi-supervised sparse feature selection framework based on Hessian regularization and l2,1/2- matrix norm, namely Hessian sparse feature selection based on L2,1/2- matrix norm (HFSL). Hessian regularization favors functions whose values vary linearly with respect to geodesic distance and preserves the local manifold structure well, leading to good extrapolating power to boost semi-supervised learning, and then to enhance HFSL performance. The l2,1/2-matrix norm model makes HFSL select the most discriminative sparse features with good robustness. An efficient iterative algorithm is designed to optimize the objective function. We apply our algorithm into the image annotation task and conduct extensive experiments on two web image datasets. The results demonstrate that our algorithm outperforms state-of-the-art sparse feature selection methods and is promising for large-scale web image applications.

With the explosive growth of the multimedia data on the Web, content-based image search has attracted considerable attentions in the multimedia and the computer vision community. The most popular approach is based on the bag-of-visual-words model with invariant local features. Since the spatial context information among local features is critical for visual content identification, many methods exploit the geometric clues of local features, including the location, the scale, and the orientation, for explicitly post-geometric verification. However, usually only a few initially top-ranked results are geometrically verified, considering the high computational cost in full geometric verification. In this paper, we propose to represent the spatial context of local features into binary codes, and implicitly achieve geometric verification by efficient comparison of the binary codes. Besides, we explore the multimode property of local features to further boost the retrieval performance. Experiments on holidays, Paris, and Oxford building benchmark data sets demonstrate the effectiveness of the proposed algorithm.

In this demo, we present an effective real-time system for ATM intelligent monitoring by using Kinect of Microsoft. With Kinect, we can easily detect people in ATM room and get their position information. By analyzing position information and video content, the system detects abnormal behaviors such as face-hiding, peeping and wandering, while records the time of these abnormal videos. Therefore, it not only prevents crimes but also helps to find suspects quickly after crimes have happened. The experimental results show that the system has the advantages of robustness, and provides a new mean for preventing financial crimes.