When deploying re-identification (ReID) models in the field of public safety, understanding the robustness of models to various types of corrupted images is crucial. Unfortunately, in the real world, images are always contaminated (e.g., noise, blur, and weather changes), which is ignored by existing visible-infrared person re-identification (VI-ReID) models. The performance of existing models tested in corrupted scenes is severely degraded. Therefore, learning corruption-invariant representations for corrupted images in VI-ReID is valuable and deserves further investigation. We design a polymorphic masked wavelet graph convolutional network for VI-ReID under corrupted scenes. Firstly, a cross-modality data augmentation algorithm is designed to construct a mixed image set that merges multi-modality attributes to improve robustness against interference. Secondly, a dual-branch network consisting of a global branch and a graph structure branch is designed. The global branch extracts overall information. While the graph structure branch is a wavelet-based graph convolutional module that utilizes the robustness of human structural information to corruptions and modalities, it can filter noise and extract discriminative features specifically targeted for cross-modality scenes. Finally, the global branch and the graph structure branch are integrated, and modality consistency loss is designed to match the branches with hetero-center triplet loss. Experiments show that our method can effectively alleviate degradation problems under corrupted environments such as noise, blur, digitization, and weather changes, and achieve state-of-the-art on corrupted datasets. Besides, it still maintains good performance on clean datasets, facilitating the reliable deployment of VI-ReID in real-world scenarios.

Abstract In the dark scene at night, the face images captured by ordinary visible light (VIS) are generally poor quality and very dim, while the near‐infrared (NIR) can capture high definition and recognizable face images at night. The NIR‐VIS Heterogeneous face recognition has become a hot research field, which helps to build an all‐weather face recognition system. NIR‐VIS HFR is sophisticated because of the large visual difference between NIR images and VIS images. In order to reduce the difficulty of such cross‐modality invariant feature learning, this paper proposes a cross‐modality data gap decomposed by auxiliary modality method (DGD) for NIR‐VIS HFR. First, the brightness component (Y component) of VIS image YCbCr space is used as the auxiliary modality to decompose the cross‐modality data gap. The lightness component retained the structural information of VIS image and was similar to the colour information of NIR modality; in this way, the huge gap between the NIR data and the VIS data is decomposed into two smaller gaps, thus reducing the difficulty of network learning. Second, the data of the three modalities are input into the weight sharing network and training under the combined guidance of cross‐modality gap decomposition loss and intra‐modality gap loss; in this way, the modality invariant features can be learned faster and better. Extensive experiments were conducted on two commonly used datasets CASIA NIR‐VIS 2.0 and Oulu‐CASIA NIR‐VIS to evaluate DGD method. Experimental results indicate DGD method has competitive performance compared with the latest methods.

Exploiting light field data makes it possible to obtain dense and accurate depth map. However, synthetic scenes with limited disparity range cannot contain the diversity of real scenes. By training in synthetic data, current learning based methods do not perform well in real scenes. In this paper, we propose a self-supervised learning framework for light field depth estimation. Different from the existing end-to-end training methods using disparity label per pixel, our approach implements network training by estimating EPI disparity shift after refocusing, which extends the disparity range of epipolar lines. To reduce the sensitivity of EPI to noise, we propose a new input mode called EPI-Stack, which stacks EPIs in the view dimension. This method is less sensitive to noise scenes than traditional input mode and improves the efficiency of estimation. Compared with other state-of-the-art methods, the proposed method can also obtain higher quality results in real-world scenarios, especially in the complex occlusion and depth discontinuity.

This letter makes a first attempt to design a cooperative relay scheme to secure wireless communications by adopting a fast-forward full-duplex (F3D) node. Different from the conventional full-duplex relay, the F3D node could process and forward the received signal immediately. With such forwarding, the forwarded signal of F3D could enhance the signal to interference plus noise ratio of the receiver, whereas weaken that of the eavesdropper and thus build up a secure channel. Beyond the proposed scheme, we move forward to optimize the signal processing design of the F3D node with the target of maximizing the secrecy capacity. The formulated optimization problem is nonconvex and challenging to deal with. We then design an iterative algorithm based on generalized fractional programming to solve it. One key step in the iterative algorithm involves another nonconvex optimization and we decompose it into a two-level optimization. Simulation results validate the effectiveness of our designed secure cooperative relay scheme and show that adopting F3D node for physical-layer security has good performance in terms of achievable secrecy capacity compared with the scheme without F3D node.

Saliency detection has recently received increasing research interest on using high-dimensional datasets beyond two-dimensional images. Despite the many available capturing devices and algorithms, there still exists a wide spectrum of challenges that need to be addressed to achieve accurate saliency detection. Inspired by the success of the light-field technique, in this article, we propose a new computational scheme to detect salient regions by integrating multiple visual cues from light-field images. First, saliency prior maps are generated from several light-field features based on superpixel-level intra-cue distinctiveness, such as color, depth, and flow inherited from different focal planes and multiple viewpoints. Then, we introduce the location prior to enhance the saliency maps. These maps will finally be merged into a single map using a random-search-based weighting strategy. Besides, we refine the object details by employing a two-stage saliency refinement to obtain the final saliency map. In addition, we present a more challenging benchmark dataset for light-field saliency analysis, named HFUT-Lytro , which consists of 255 light fields with a range from 53 to 64 images generated from each light-field image, therein spanning multiple occurrences of saliency detection challenges such as occlusions, cluttered background, and appearance changes. Experimental results show that our approach can achieve 0.6--6.7% relative improvements over state-of-the-art methods in terms of the F-measure and Precision metrics, which demonstrates the effectiveness of the proposed approach.

The authors extend exemplar representation to the field of tracking and propose a robust tracking algorithm with per‐exemplar support vector machine (SVM) classifiers. First, the authors train the simple yet effective exemplar SVM classifier using the target object as the single positive and mining its surroundings as hard negatives. Second, the authors propose an online ensemble tracker, which integrates the useful ‘key historical templates’ of the target to refine the current template, leading to better discriminative power of tracker and effectively decreasing the risk of drift. Experiments on challenging sequences demonstrate that the tracker performs well in accuracy and robustness, especially under the sequences with strong illumination variation and scale variation, as well as pose change and partial occlusion in the long‐time sequence.

Recent studies have shown that sparse representation (SR) can deal well with many computer vision problems, and its kernel version has powerful classification capability. In this paper, we address the application of a cooperative SR in semi-supervised image annotation which can increase the amount of labeled images for further use in training image classifiers. Given a set of labeled (training) images and a set of unlabeled (test) images, the usual SR method, which we call forward SR, is used to represent each unlabeled image with several labeled ones, and then to annotate the unlabeled image according to the annotations of these labeled ones. However, to the best of our knowledge, the SR method in an opposite direction, that we call backward SR to represent each labeled image with several unlabeled images and then to annotate any unlabeled image according to the annotations of the labeled images which the unlabeled image is selected by the backward SR to represent, has not been addressed so far. In this paper, we explore how much the backward SR can contribute to image annotation, and be complementary to the forward SR. The co-training, which has been proved to be a semi-supervised method improving each other only if two classifiers are relatively independent, is then adopted to testify this complementary nature between two SRs in opposite directions. Finally, the co-training of two SRs in kernel space builds a cooperative kernel sparse representation (Co-KSR) method for image annotation. Experimental results and analyses show that two KSRs in opposite directions are complementary, and Co-KSR improves considerably over either of them with an image annotation performance better than other state-of-the-art semi-supervised classifiers such as transductive support vector machine, local and global consistency, and Gaussian fields and harmonic functions. Comparative experiments with a nonsparse solution are also performed to show that the sparsity plays an important role in the cooperation of image representations in two opposite directions. This paper extends the application of SR in image annotation and retrieval.

Pattern matching with both gap constraints and the one-off condition is a challenging topic, especially in bioinformatics, information retrieval, and dictionary query. Among the algorithms to solve the problem, the most efficient one is SAIL, which is time consuming, especially when the pattern is long. In addition, existing algorithms based on bit-parallelism cannot handle a pattern that has only one pattern character between successive wildcards and the minimum local length constraints are zero. We propose an algorithm BPBM to handle online sequential pattern matching. In BPBM, an extended bit-parallelism operation is used to accelerate the matching process. An effective transition window mechanism with two nondeterministic finite state automatons (NFAs) is adopted to drop the useless scan window. It identifies gap constraints automatically and just scans once to export occurrences with exact match positions. Theoretical analysis and experimental results show that the BPBM algorithm is more competitive than other peers. It has an absolute advantage on search time complexity. It also has better stability that decreases operation costs with the increasing of the size of sequence alphabet or the length of the pattern. We also study off-line pattern matching. With twice pruning, left-most and right-most, we can increase the matching ratio about 2.08% on average.

Sequential pattern mining is an important research task in many domains, such as biological science. In this paper, we study the problem of mining frequent patterns from sequences with wildcards. The user can specify the gap constraints with flexibility. Given a subject sequence, a minimal support threshold and a gap constraint, we aim to find frequent patterns whose supports in the sequence are no less than the given support threshold. We design an efficient mining algorithm MAIL that utilizes the candidate occurrences of the prefix to compute the support of a pattern that avoids the rescanning of the sequence. We present two pruning strategies to improve the completeness and the time efficiency of MAIL. Experiments show that MAIL mines 2 times more patterns than one of its peers and the time performance is 12 times faster on average than its another peer.

This paper focuses on the issues about the complex relations in large-scale FCM, and then proposes a promising method for weight global optimization with local inference to analyze and predict indexes in Anhui sci-tech progress monitor system. Firstly, a new concept, unbalanced degree, is introduced for standard evaluation in FCM model to modify the weight assessment factors and result in the satisfied convergence rate. Secondly, relations between unbalanced degree and convergence error are also presented for further analysis with training error and guarantee on perfect condition in model. Thirdly, local inference in FCM is discussed to enhance prediction accuracy rate. Finally, experimental result reveals successful application of FCM in large-scale complex sci-tech systems.