Infrared and visible image fusion (IVIF) technology has become a frontier of great interest due to the ability to integrate information from multiple sources. However, the progressive slowdown of weight updates in deep networks (i.e., “network laziness” phenomenon), makes existing methods far from realizing the full characterization potential. To this end, we propose a lightweight fusion method for IVIF, Anti-Inert Dynamic Fusion (AIDFusion), to fully utilize the potential of the network at all levels. Specifically, by progressively regulating the collaborative Learning process of multi-level prediction in the network, Dynamic Inertia Inhibition Learning Strategy (DIILS) is proposed to adaptively and efficiently inhibit inertia accumulation. Subsequently, to deeply explore the representation potential while breaking through the performance threshold, lightweight Multi-dimensional modulation fusion module (MMFM) is specifically proposed to capture comprehensive multi-view and multi-scale features efficiently. Finally, considering the semantic bias between the prediction maps of DIILS and the fusion feature of MMFM, Fourier Analysis Convolution (FAConv) is designed in feature recovery as a bridge between prediction and fusion to accomplish the implicit periodic modeling. Based on the above study, extensive experiments on three public IVIF datasets demonstrate the dual advantages of AIDFusion in terms of fusion performance and computational overhead compared to state-of-the-art baseline methods.

In semi‑supervised multi‑view classification (SMVC), scarce labels and noisy unlabeled data impair feature aggregation and compromise prediction reliability, while existing methods lack principled guidance and interpretability. To overcome these limitations, we propose a novel unified SMVC framework, Neural Collapse Priors Driven Trust Semi-Supervised Multi-View Classification (NCPD-TSMVC), building upon neural collapse–derived prototype priors and evidential opinion fusion. Concretely, we rigorously prove under neural collapse theory that normalized classifier weights from the labeled‑data pre‑training stage coincide with class centroids in feature space, conferring maximal inter‑class separation and optimal within‑class compactness. These prototype priors permeate the entire learning pipeline, calibrating the representation learning of unlabeled samples to obtain highly discriminative embeddings. Simultaneously, our evidential learning module quantifies epistemic uncertainty and fuses view‑level opinions at the evidence level, yielding robust and transparent decision making. Extensive evaluations across diverse benchmarks demonstrate that NCPD‑TSMVC surpasses state‑of‑the‑art SMVC approaches in performance, robustness and interpretability.

Dynamic LiDAR point cloud compression with range images aims to reduce storage and transmission costs while preserving both spatial accuracy and temporal consistency across frames. Vision Transformers (ViTs) are commonly used for cross-frame dependency modeling. However, they suffer from feature misalignment under cross-frame displacement due to fixed patch partitioning, and their global attention across all patches is costly yet ineffective for local motions. High-precision sequences also face precision loss when 16-bit range data are quantized in a single channel. To address these limitations, we propose a Slide Deformable Transformer framework for high-precision dynamic LiDAR point cloud compression, termed SDT-PCC. At its core, the proposed SDT layer restricts attention to local sliding windows, capturing fine-grained correspondences across consecutive frames. It integrates deformable convolution into cross-frame attention to adaptively sample motion-offset locations, thereby enhancing temporal alignment and motion modeling. We also propose a Radix-Decomposition Multi-Channel Quantizer (RDMCQ), which decomposes range values into multiple channels and progressively refines precision across radix levels. Consequently, these designs can produce more temporally-coherent, accurate and stable reconstructions. Experiments on the SemanticKITTI dataset show that SDT-PCC achieves high efficiency in dynamic point cloud compression. The code is available on https://github.com/SYSU-SAIL/SDT-PCC.

With the increasing accessibility of multimodal data, cross-modal retrieval (CMR) has gained significant attention in recent years. However, most existing CMR methods are built on clean annotations and closed-set label space assumptions, which are often violated in practice. In realistic scenarios, annotations are often noisy due to machine-generated or non-expert labeling, while new categories may also emerge from heterogeneous data sources. The coexistence of label noise and open-set categories gives rise to open-set noisy labels (OSNL). Compared to closed-set noise, OSNL is more harmful because it arises from samples whose true categories lie outside the training label space. When such unknown-class samples are incorrectly assigned to known labels, the model cannot correct them through label relationships. Instead, the model is forced to learn erroneous semantic associations, embedding unknown semantics into incorrect categories. This bias gradually accumulates and disrupts the semantic structure of the shared representation space, ultimately causing existing CMR methods to struggle to maintain reliable performance. To address these challenges, this paper proposes NOise-TOlerate evidential learning (NOTO), a novel framework that robustly learns cross-modal representations under both closed-set and open-set noisy labels. Specifically, a Robust Evidential Learning (REL) module is proposed to detect clean, closed-set noisy, and open-set noisy instances by modeling the predictive distribution as Dirichlet evidence and inferring belief masses. Based on these inferred instance types, REL then assigns tailored optimization strategies to enhance semantic consistency and enlarge the discrimination margin between in-distribution data and open-set categories. An Adaptive Noise-aware Contrast (ANC) module is proposed to adaptively select reliable positive pairs according to the estimated noise states and maximize the mutual information between them to strengthen cross-modal alignment and mitigate the adverse effects of noisy supervision simultaneously. Extensive experiments and comparisons with ten state-of-the-art CMR methods on four benchmarks demonstrate that NOTO achieves superior retrieval performance and robustness against open-set noisy labels. The code is available at https://github.com/perquisite/NOTO.

Cross-modal hashing (CMH) has appeared as a popular technique for cross-modal retrieval due to its low storage cost and high computational efficiency in large-scale data. Most existing methods implicitly assume that multi-modal data is correctly labeled, which is expensive and even unattainable due to the inevitable imperfect annotations (i.e., noisy labels) in real-world scenarios. Inspired by human cognitive learning, a few methods introduce self-paced learning to gradually train the model from easy to hard samples, which is often used to mitigate the effects of feature noise or outliers. It is a less-touched problem that how to utilize SPL to alleviate the misleading of noisy labels on the hash model. To tackle this problem, we propose a new cognitive cross-modal retrieval method called Robust Self-paced Hashing with Noisy Labels (RSHNL), which can mimic the human cognitive process to identify the noise while embracing robustness against noisy labels. Specifically, we first propose a contrastive hashing learning (CHL) scheme to improve multi-modal consistency, thereby reducing the inherent semantic gap. Afterward, we propose center aggregation learning (CAL) to mitigate the intra-class variations. Finally, we propose Noise-tolerance Self-paced Hashing (NSH) that dynamically estimates the learning difficulty for each instance and distinguishes noisy labels through the difficulty level. For all estimated clean pairs, we further adopt a self-paced regularizer to gradually learn hash codes from easy to hard. Extensive experiments demonstrate that the proposed RSHNL performs remarkably well over the state-of-the-art CMH methods.

In recent years, anchor and hash-based multi-view clustering methods have gained attention for their efficiency and simplicity in handling large-scale data. However, existing methods often overlook the interactions among multi-view data and higher-order cooperative relationships during projection, negatively impacting the quality of hash representation in low-dimensional spaces, clustering performance, and sensitivity to noise. To address this issue, we propose a novel approach named Tensor-Interacted Projection and Cooperative Hashing for Multi-View Clustering(TPCH). TPCH stacks multiple projection matrices into a tensor, taking into account the synergies and communications during the projection process. By capturing higher-order multi-view information through dual projection and Hamming space, TPCH employs an enhanced tensor nuclear norm to learn more compact and distinguishable hash representations, promoting communication within and between views. Experimental results demonstrate that this refined method significantly outperforms state-of-the-art methods in clustering on five large-scale multi-view datasets. Moreover, in terms of CPU time, TPCH achieves substantial acceleration compared to the most advanced current methods.

In recent years, multi-view learning has aroused extensive research passion. Most existing multi-view learning methods often rely on well-annotations to improve decision accuracy. However, noise labels are ubiquitous in multi-view data due to imperfect annotations. To deal with this problem, we propose a novel noisy label calibration method (NLC) for multi-view classification to resist the negative impact of noisy labels. Specifically, to capture consensus information from multiple views, we employ max-margin rank loss to reduce the heterogeneous gap. Subsequently, we evaluate the confidence scores to enrich predictions associated with noise instances according to all reliable neighbors. Further, we propose Label Noise Detection (LND) to separate multi-view data into a clean or noisy subset, and propose Label Calibration Learning (LCL) to correct noisy instances. Finally, we adopt the cross-entropy loss to achieve multi-view classification. Extensive experiments on six datasets validate that our method outperforms eight state-of-the-art methods.

Multi-view clustering (MVC) aims to exploit complementary information from diverse views to enhance clustering performance. Since pseudo-labels can provide additional semantic information, many MVC methods have been proposed to guide unsupervised multi-view learning through pseudo-labels. These methods implicitly assume that the predicted pseudo-labels are predicted correctly. However, due to the challenges in training a flawless unsupervised model, this assumption can be easily violated, thereby leading to the Noisy Pseudo-label Problem (NPP). Moreover, these existing approaches typically rely on the assumption of perfect cross-view alignment. In practice, it is frequently compromised due to noise or sensor differences, thereby resulting in the Noisy Correspondence Problem (NCP). Based on the above observations, we reveal and study unsupervised multi-view learning under NPP and NCP. To this end, we propose Robust Noisy Pseudo-label Learning (ROLL) to prevent the overfitting problem caused by both NPP and NCP. Specifically, we first adopt traditional contrastive learning to warm up the model, thereby generating the pseudo-labels in a self-supervised manner. Afterward, we propose noise-tolerance pseudo-label learning to deal with the noise in the predicted pseudo-labels, thereby embracing the robustness against NPP. To further mitigate the overfitting problem, we present robust multi-view contrastive learning to mitigate the negative impact of NCP. Extensive experiments on five multi-view datasets demonstrate the superior clustering performance of our ROLL compared to 11 state-of-the-art methods.

Physics-informed neural networks (PINNs) aim to constrain the outputs and gradients of deep learning models to satisfy specified governing physics equations, which have demonstrated significant potential for solving partial differential equations (PDEs). Although existing PINN methods have achieved pleasing performance, they always treat both easy and hard sample points indiscriminately, especially ones in the physical boundaries. This easily causes the PINN model to fall into undesirable local minima and unstable learning, thereby resulting in an Unbalanced Prediction Problem (UPP). To deal with this daunting problem, we propose a novel framework named Cognitive Physical Informed Neural Network (CoPINN) that imitates the human cognitive learning manner from easy to hard. Specifically, we first employ separable subnetworks to encode independent one-dimensional coordinates and apply an aggregation scheme to generate multi-dimensional predicted physical variables. Then, during the training phase, we dynamically evaluate the difficulty of each sample according to the gradient of the PDE residuals. Finally, we propose a cognitive training scheduler to progressively optimize the entire sampling regions from easy to hard, thereby embracing robustness and generalization against predicting physical boundary regions. Extensive experiments demonstrate that our CoPINN achieves state-of-the-art performance, particularly significantly reducing prediction errors in stubborn regions.

Recently, numerous cross-modal hashing (CMH) methods have been proposed, yielding remarkable progress. As a static learning paradigm, existing CMH methods often implicitly assume that all modalities are prepared before processing. However, in practice applications (such as multi-modal medical diagnosis), it is very challenging to collect paired multi-modal data simultaneously. Specifically, they are collected chronologically, forming streaming-media data (SMA). To handle this, all previous CMH methods require retraining on data from all modalities, which inevitably limits the scalability and flexibility of the model. In this paper, we propose a novel CMH paradigm named Streaming-media Hashing rEtrieval (SHE) that enables parallel training of each modality. Specifically, we first propose a knowledge library mining module (KLM) that extracts a prototype knowledge library for each modality, thereby revealing the commonality distribution of the instances from each modality. Then, we propose a knowledge library transfer module (KLT) that updates and aligns the new knowledge by utilizing the historical knowledge library, ensuring semantic consistency. Finally, to enhance intra-class semantic relevance and inter-class semantic disparity, we develop a discriminative hashing learning module (DHL). Comprehensive experiments on four benchmark datasets demonstrate the superiority of our SHE compared to 14 competitors.

Existing deep multi-view clustering methods have demonstrated excellent performance, which addressing issues such as missing views and view noise. But almost all existing methods are within a static framework, which assumes that all views have already been collected. However, in practical scenarios, new views are continuously collected over time, which forms the stream of views. Additionally, there exists the data imbalance of quality and distribution between different view streams, i.e., concept drift problem. To this end, we propose a novel Deep Streaming View Clustering (DSVC) method, which mitigates the impact of concept drift on streaming view clustering. Specifically, DSVC consists of a knowledge base and three core modules. Through the knowledge aggregation learning module, DSVC extracts representative features and prototype knowledge from the new view. Subsequently, the distribution consistency learning module aligns the prototype knowledge from the current view with the historical knowledge distribution to mitigate the impact of concept drift. Then, the knowledge guidance learning module leverages the prototype knowledge to guide the data distribution and enhance the clustering structure. Finally, the prototype knowledge from the current view is updated in the knowledge base to guide the learning of subsequent views. Extensive experiments demonstrate that, even in dynamic environments, the clustering performance of DSVC outperforms 12 state-of-the-art DMVC methods under static frameworks.

In recent years, multi-view clustering (MVC) has become a promising approach for analyzing heterogeneous multi-source data. However, during the collection of multi-view data, factors such as environmental interference or sensor failure often lead to the loss of view sample data, resulting in incomplete multi-view clustering (IMVC). Graph contrastive IMVC has demonstrated promising performance as an effective solution, which typically utilizes in-graph instances as positive pairs and out-of-graph instances as negative pairs. However, the construction of positive and negative pairs in this paradigm inevitably leads to graph noise Correspondence (GNC). To this end, we propose a new IMVC framework, namely robust graph contrastive learning (RGCL). Specifically, RGCL first completes the missing data by using a multi-view consistency transfer relationship graph. Then, to mitigate the impact of false negative pairs from graph contrastive, we propose noise-robust graph contrastive learning to mine intra-view consistency accurately. Finally, we present cross-view graph-level alignment to fully exploit the complementary information across different views. Experimental results on the six multi-view datasets demonstrate that our RGCL exhibits superiority and effectiveness compared with 9 state-of-the-art IMVC methods. The source code is available at https://github.com/DYZ163/RGCL.git.

Anchor-based strategies have become the dominant paradigm for large-scale multi-view clustering, where the quality and representational capacity of anchors are crucial to clustering performance. Existing methods typically learn anchors adaptively, focusing only on dynamically selecting anchors from the original data. However, these methods often lack an information-theoretic metric to evaluate how effectively the selected anchors capture the intrinsic characteristics of their respective clusters. Moreover, few approaches attempt to enhance the internal structure of anchor matrix to further improve clustering performance. To address these challenges, we propose a novel Anchor-Driven High-Throughput Encoding (ADHTE) framework that optimizes anchors by maximizing their throughput encoding capacity. In this method, the High-Throughput Encoding rate serves as a metric for anchor effectiveness, and we employ a deep neural network to optimize the anchor matrix. In addition, we predefine a clustering indicator matrix to construct a consistent anchor matrix across views, thereby ensuring anchor alignment. Furthermore, we propose an edge-alignment learning scheme to produce a bipartite graph with consistent edges across views. Extensive experiments on eight benchmark datasets demonstrate that the proposed ADHTE framework exhibits superior effectiveness and robustness compared to other state-of-the-art methods. The code of this paper is released on https://github.com/enjoypiker/ADHTE.

As information acquisition diversifies, data is acquired and stored in increasing modalities. However, sensor failures or equipment issues can lead to partial data loss in certain views, resulting in incomplete multi-view clustering (IMVC) problems. Although some prototype-based IMVC methods have achieved satisfactory performance, almost all of these methods implicitly assume that the cross-view prototypes are aligned. However, during the generation or selection of prototypes, different networks could produce different prototypes, thereby leading to potential misalignment of prototypes across views, i.e., prototype-unaligned problem (PUP). The presence of PUP could lead to overfitting the model. Additionally, when recovering the missing data, there is uncertainty in data quality under different missing rates, which could lead to the performance instability problem (PIP). To address these issues, we propose Prototype Matching Learning for Incomplete Multi-view Clustering (PMIMC). Specifically, PMIMC leverages relational consistency learning to mitigate the heterogeneity of multi-view data. Subsequently, we design a robust prototype contrastive learning loss for the generated prototypes to reduce the effects of PUP. Finally, we propose a prototype-based imputation strategy, that aims to alleviate the instability of imputation under high missing rates. Extensive experiments demonstrate that PMIMC outperforms 13 state-of-the-art methods in terms of clustering performance and robustness. The code is available at: https: //github.com/hl-yuan/PMIMC.

Multi-view clustering (MVC) can fuse the information of multiple views for robust clustering result, among it two fusion strategies,early-fusionandlate-fusionare widely adopted. Although they have derived many MVC methods, there are still two crucial questions: (1)early-fusionforces multiple views to share a consensus latent representation, which compounds the challenge of excavating view-specific diverse local information; (2)late-fusiongenerates view-partitions independently and then integrates them in the following clustering procedure, where the two procedures cannot guide each other and lack necessary negotiation. In view of this, we propose a novel Graph Proxy Fusion (GPF) method to preserve and fuse view-specific local information concertedly in one unified framework. Specifically, we first propose anchor-based local information learning to capture view-specific local structural information in bipartite graphs; meanwhile, a view-consensus graph learned through self-expressiveness-based proxy graph learning module is deemed as a higher-order proxy; following, the novel graph proxy fusion module integrally embeds all lower-order bipartite graphs in the higher-order proxy via higher-order correlation theory. As a novel fusion strategy, the proposed GPF efficiently investigates the valuable consensus and diverse information of multiple views. Experiments on various multi-view datasets demonstrate the superiority of our method.

Compared to static anchor selection, existing dynamic anchor learning could automatically learn more flexible anchors to improve the performance of large-scale multi-view clustering. Despite improving the flexibility of anchors, these methods do not pay sufficient attention to the alignment and fairness of learned anchors. Specifically, within each cluster, the positions and quantities of cross-view anchors may not align, or even anchor absence in some clusters, leading to severe anchor misalignment and imbalance issues. These issues result in inaccurate graph fusion and a reduction in clustering performance. Besides, in practical applications, missing information caused by sensor malfunctions or data losses could further exacerbate anchor misalignment and imbalance. To overcome such challenges, a novel Incomplete Multi-view Clustering withPaired and Balanced Dynamic Anchor Learning (PBDAL)is proposed to ensure the alignment and fairness of anchors. Unlike existing unsupervised anchor learning, we first design a paired and balanced dynamic anchor learning scheme to supervise dynamic anchors to be aligned and fair in each cluster. Meanwhile, we develop an enhanced bipartite graph tensor learning to refine paired and balanced anchors. Our superiority, effectiveness, and efficiency are all validated by performing extensive experiments on multiple public datasets.

Multiview clustering (MVC) can achieve more accurate results by utilizing complementary information from multiple perspectives, compared to traditional single-view methods. However, current multiview techniques require all views to be available upfront, making them inadequate for dealing with prevalent data sources that arrive as streams, such as stem cell analysis and multicamera surveillance. To address this problem, in this article, we propose a method called lifelong stream-view clustering (LSVC), which comprises an embedding anchor knowledge library and three key components, enabling the capability to perform asynchronous clustering on stream views. These three components are specifically: 1) the knowledge extraction module that extracts the abstract knowledge of the newcome view over time and updates the shared knowledge library; 2) the knowledge transfer module that aligns the newcome view with the historical knowledge library, enabling the transfer of structure information to the knowledge library; and 3) the knowledge rule module that constraints the knowledge library to enjoy a fair amount of anchors for each cluster, improving the discrimination of knowledge. The experimental results show that LSVC outperforms traditional single-view clustering (SVC) and MVC methods as it gradually improves with the accumulation of stream views and tends to be stable over time.

Cross-modal hashing~(CMH) is an efficient technique to retrieve relevant data across different modalities, such as images, texts, and videos, which has attracted more and more attention due to its low storage cost and fast query speed. Although existing CMH methods achieve remarkable processes, almost all of them treat all samples of varying difficulty levels without discrimination, thus leaving them vulnerable to noise or outliers. Based on this observation, we reveal and study dual difficulty levels implied in cross-modal hashing learning, \ie instance-level and feature-level difficulty. To address this problem, we propose a novel Dual Self-Paced Cross-Modal Hashing (DSCMH) that mimics human cognitive learning to learn hashing from ``easy'' to ``hard'' in both instance and feature levels, thereby embracing robustness against noise/outliers. Specifically, our DSCMH assigns weights to each instance and feature to measure their difficulty or reliability, and then uses these weights to automatically filter out the noisy and irrelevant data points in the original space. By gradually increasing the weights during training, our method can focus on more instances and features from ``easy'' to ``hard'' in training, thus mitigating the adverse effects of noise or outliers. Extensive experiments are conducted on three widely-used benchmark datasets to demonstrate the effectiveness and robustness of the proposed DSCMH over 12 state-of-the-art CMH methods.

With the massive emergence of multi-modal data, cross-modal retrieval (CMR) has become one of the hot topics. Thanks to fast retrieval and efficient storage, cross-modal hashing (CMH) provides a feasible solution for large-scale multi-modal data. Previous CMH methods always directly learn common hash codes to fuse different modalities. Although they have obtained some success, there are still some limitations: 1) These approaches often prioritize reducing the heterogeneity in multi-modal data by learning consensus hash codes, yet they could sacrifice modality-specific information. 2) They frequently utilize pairwise similarities to guide hashing learning and neglect class distribution correlations. To overcome these two issues, we propose a novel Distribution Consistency Guided Hashing (DCGH) framework. Specifically, we first learn the modality-specific representation to extract the private discriminative information. Further, we learn consensus hash codes from the private representation by consensus hashing learning, thereby merging the specifics with consistency. Finally, we propose distribution consistency learning to guide hash codes following a similar class distribution principle between multi-modal data, thereby exploring more consistent information. Lots of experimental results on four benchmark datasets demonstrate the effectiveness of our DCGH on both fully paired and partially paired CMR tasks. The code can be available at: https://github.com/sunyuan-cs/2024-MM-DCGH.

Recently, tensor Schatten p-norm has achieved impressive performance for fast multi-view clustering [57]. This primarily ascribes the superiority of tensor Schatten p-norm in exploring high-order structure information among views. Whereas, 1) tensor Schatten p-norm treats different singular values equally, such that the larger singular values corresponding to certain significant feature information (i.e., prior information) have not been utilized fully; 2) tensor Schatten p-norm also ignore ranking the core entries of core tensor, which may contain noise information; 3) existing methods select fixed anchors or averagely update anchors to construct the neighbor bipartite graphs, greatly limiting the flexibility and expression of anchors. To break these limitations, we propose a novel Improved Weighted Tensor Schatten p-Norm for Fast Multi-view Graph Clustering (IWTSN-FMGC). Specifically, to eliminate the interference of the first two limitations, we propose an improved weighted tensor Schatten p-norm to dynamically rank core tensor and automatically shrink singular values. To this end, improved weighted tensor Schatten p-norm has the potential to more effectively leverage low-rank structures and prior information, thereby enhancing robustness compared to current tensor Schatten p-norm methods. Further, the designed adaptive neighbor bipartite graph learning can more flexibly and expressively encode the local manifold structure information than existing anchor selection and averaged anchor updating. Extensive experiments validate our effectiveness and superiority across multiple benchmark datasets.

Multiple kernel clustering (MKC) has garnered considerable attention, as their efficacy in handling nonlinear data in high-dimensional space. However, current MKC methods have three primary issues: (1) Solely focuses on clustering information while neglecting energy information and potential noise interference within the kernel; (2) The inherent manifold structure in the high-dimensional space is complex, and they lack the insufficient exploration of topological structure; (3) Most encounter cubic computational complexity, posing a formidable resource consumption challenge. To tackle the above issues, we propose a novel MKC method with shifted Laplacian on Grassmann manifold (sLGm). Firstly, sLGm constructs r-rank shifted Laplacian and subsequently reconstructs it, retaining the clustering-related and energy-related information while reducing the influence of noise. Additionally, sLGm introduces a Grassmann manifold for information fusion, which can preserve topological information in the high-dimensional space. Notably, an optimal consensus partition can be concurrently learnt from above two procedures, thereby yielding the clustering assignments, and the computational complexity of the whole procedure drops to the quadratic. Conclusively, a comprehensive suite of experiments is executed to roundly prove the effectiveness of sLGm.

In practical data collection processes, certain views may become partially unavailable due to sensor failures or equipment issues, leading to the problem of incomplete multi-view clustering (IMVC). While some IMVC methods employing prototype completion achieve satisfactory performance, almost all of them implicitly assume correct alignment of prototypes across all views. However, during prototype generation, different networks could generate different cluster centers, thereby leading to the produced prototypes from different views may be misaligned, \ie prototype noisy correspondence. To address this issue, we propose Robust Prototype Completion for Incomplete Multi-view Clustering (RPCIC), which mitigates the impact of noisy correspondence in prototypes. Specifically, RPCIC initially utilizes cross-view contrastive learning module to obtain consistent feature representations across different views. Subsequently, we devise robust contrastive loss for the produced prototypes, aiming to alleviate the influence of noisy correspondence within them. Finally, we employ prototype fusion-based strategy to complete the missing data. Comprehensive experiments demonstrate that RPCIC outperforms 11 state-of-the-art methods in terms of both performance and robustness. The code is available at https://github.com/hl-yuan/RPCIC.

Most deep multi-view subspace clustering (DMVSC) methods usually employ pipeline optimization by learning the self-expression with a deep model first and then applying spectral clustering to group multi-view data. Subsequently, end-to-end DMVSC methods have been proposed by integrating these two steps into a unified optimization framework. However, the pipeline methods may suffer from misaligned clustering accumulation due to the noise or outlying entries, and the end-to-end methods often constitute a relatively complex parameter optimization. In this paper, we propose a novel method named decomposed deep multi-view subspace clustering with self-labeling supervision (D 2 MVSC) that runs with a decomposed optimization strategy by three-stage training. Specifically, multi-scale features are extracted by autoencoder in the pre-training stage. According to the discriminative contribution of each view, consensus self-expression is learned from these features by adaptive fusion and structure supervision to generate high-quality pseudo-labels in the fine-tuning stage. Finally, the pseudo-labels are used to retrain the model in a self-labeling supervision manner for robust clustering. Exciting, the self-labeling supervision can be used as an add-on module for other DMVSC methods to improve clustering performance. Extensive experiments on six datasets verify the effectiveness and superiority of our method over other state-of-the-art methods.

Tensor structures are widely utilized in clustering tasks due to their ability to represent high-order relationships among multi-view data. The rank and decomposition of tensors are essential characteristics that have recently received considerable attention. Most approaches approximate tensor rank using the tensor nuclear norm (TNN) and non-convex rank functions. We introduce a multi-view clustering method based on an enhanced self-expression with a tensor double arc-tangent norm. Initially leveraging tensor singular value decomposition , this method impartially approximates the true rank of the tensor, avoiding rank overestimation. The enhanced self-expression further utilizes the latent connections among the original data. Then, we propose an improved alternating direction method of multipliers (ADMM) for rapid optimization of the model. Experiments conducted on six datasets confirm the effectiveness of the proposed model.

The existing multikernel graph clustering (MKGC) methods have emerged with notable success on nonlinear clustering tasks since the graph learning can effectively capture graph structure similarity between sample pair. Ideally, a high-quality graph should enjoy the good block diagonal property, i.e. the intercluster similarities correspond to zeros, while intracluster similarities represent nonzeros. Meanwhile, the number of diagonal blocks for a graph equals to the number of clusters on the dataset. However, most of the existing MKGC methods design a corpulent three-parts graph leaning process that poses challenges for hyperparameter tuning, time cost, and clustering performance. To overcome these challenging issues, we propose an enforced block diagonal graph learning for multikernel clustering (EBDGL-MKC) method, where we pursue a high-quality block diagonal graph via well-designed one-part graph leaning scheme rather than three parts. Inspired by symmetric matrix factorization (SMF), we first design a one-part block diagonal graph learning scheme to learn multiple block diagonal graphs, by exploring an explicit theoretical connection between the clustering partition of kernel$k$-means and the excellent block diagonal graph. Then, these block diagonal graphs are stacked into a low-rank tensor for exploiting the high-order structure information hidden in the nonlinear data. After that, an effective alternate algorithm with convergence proof is performed on extensive experiments to demonstrate the superiority of EBDGL compared with the state-of-the-art multikernel clustering (MKC) methods.

Image retrieval is the eye of industrial robots, which determines the performance of machine visual search, street view search, and object grasping. Learning to hash, as a promising technique, has attracted much attention. Existing image hashing methods often directly learn hash codes by a single hash function. Despite their success, they suffer from the following limits: 1) It is difficult to perfectly preserve the intrinsic structure of the data using a single-layer hash function to generate discriminative hash codes; 2) they unconsciously ignore the main energy information of the original data, which lead to severe information loss of low-dimensional hash codes. To alleviate these issues, we propose a concise yet effective Relaxed Energy Preserving Hashing (REPH) method. Specifically, we utilize a two-layer hash function to provide more flexibility, thereby learning discriminant hash codes. The first-layer hash function projects the image data into a transition space, and the second-layer hash function narrows the semantic gap between features and hash codes. Then, we propose an energy preserving strategy to retain the energy of the original data in the transition space, thereby alleviating the energy loss of hash projecting. Moreover, the semantic reconstruction mechanism is proposed to guarantee the semantic information can be well preserved into hash codes. Extensive experiments demonstrate the superior performance of the proposed REPH on five real-world image datasets. Our source code has been released at https://github.com/sunyuan-cs/REPH_main.

In recent years, image hashing has attracted more and more attention in practical retrieval applications due to its low storage cost and high query speed. Although existing hashing methods have achieved promising performance, they always treat both easy and hard points without discrimination, thus easily getting stuck into bad local minima, especially in the presence of noise or outliers. In this paper, we reveal that there exist dual difficulty levels hindering binarization in learning to hash, i.e., samples and bits. To overcome this problem, we propose a novel Dual Self-Paced Hashing method (DSPH) for image retrieval, which learns binary codes by not only evolving from ‘easy’ to ‘hard’ samples but also from ‘easy’ to ‘hard’ bits, mimicking the cognitive learning process from easy to difficult. Specifically, we endow each sample and bit with a weight to estimate the reliability/ ease of the row and column, respectively. Then both sampleand bit-level weighting are conducted on rows and columns of Hamming space to enforce the model focus on reliable/easy examples and bits. By gradually increasing the weights during model optimization, more samples and bits are automatically involved in training from ‘easy’ to ‘hard’ via our dual self-paced method, thereby alleviating the adverse impact caused by noises or outliers to learn robust hashing models. Extensive experiments are conducted on four benchmark datasets to demonstrate the superiority and robustness of the proposed DSPH. Our source code has been released athttps://github.com/sunyuan-cs/DSPH.

Cross-modal hashing (CMH) has gained much attention due to its effectiveness and efficiency in facilitating efficient retrieval between different modalities. Whereas, most existing methods unconsciously ignore the hierarchical structural information of the data, and often learn a single-layer hash function to directly transform cross-modal data into common low-dimensional hash codes in one step. This sudden drop of dimension and the huge semantic gap can cause the discriminative information loss. To this end, we adopt a coarse-to-fine progressive mechanism and propose a novelHierarchical Consensus Cross-Modal Hashing (HCCH). Specifically, to mitigate the loss of important discriminative information, we propose a coarse-to-fine hierarchical hashing scheme that utilizes a two-layer hash function to refine the beneficial discriminative information gradually. And then, the$\ell _{2,1}$-norm is imposed on the layer-wise hash function to alleviate the effects of redundant and corrupted features. Finally, we present consensus learning to effectively encode data into a consensus space in such a progressive way, thereby reducing the semantic gap progressively. Through extensive contrast experiments with some advanced CMH methods, the effectiveness and efficiency of our HCCH method are demonstrated on four benchmark datasets.

For robust and effective tracking, most efforts strive to design a powerful representation target model, while we are inspired by the idea of“knowing oneself and knowing others”to major in both the target and non-target features. In this work, we propose a unit correlation with interactive feature tracker (UCIF), which utilizes feature interaction and independent correlation operation to improve robustness and effectiveness. Specifically, we first propose a feature integration network, in which the feature enhancement module concentrates on enhancing the tracker's representation ability for both target and non-target. The feature interaction module is in charge of completing the interactive learning between target and non-target features. Then, considering the potential risk of blurring spatial information in regular correlation operation, a unit correlation network is presented, where the convolution sampling strategy can integrate the target features as well as reduce the computation costs. The unit kernel for correlation operation can protect the target spatial information. The channel ranking module suppresses background interference via weight assignment. Extensive experiments are conducted on both the short-term and long-term challenging benchmarks, including OTB2015, NFS, UAV123, TrackingNet, GOT-10 k, TLP, LaSOT and VOT-LT2019. Our tracker achieves remarkable performance in robustness and effectiveness.

Graph learning can effectively characterize the similarity structure of sample pairs, hence multiple kernel clustering based on graph learning (MKC-GL) achieves promising results on nonlinear clustering tasks. However, previous methods confine to a “three-stage” scheme, that is, affinity graph learning, Laplacian construction, and clustering indicator extracting, which results in the information distortion in the step alternating. Meanwhile, the energy of Laplacian reconstruction and the necessary cluster information cannot be preserved simultaneously. To address these problems, we propose a one-stage shifted Laplacian refining (OSLR) method for multiple kernel clustering (MKC), where using the “one-stage” scheme focuses on Laplacian learning rather than traditional graph learning. Concretely, our method treats each kernel matrix as an affinity graph rather than ordinary data and constructs its corresponding Laplacian matrix in advance. Compared to the traditional Laplacian methods, we transform each Laplacian to an approximately shifted Laplacian (ASL) for refining a consensus Laplacian. Then, we project the consensus Laplacian onto a Fantope space to ensure that reconstruction information and clustering information concentrate on larger eigenvalues. Theoretically, our OSLR reduces the memory complexity and computation complexity to$O(n)$and$O(n^2)$, respectively. Moreover, experimental results have shown that it outperforms state-of-the-art MKC methods on multiple benchmark datasets.

Although multi-view clustering (MVC) has achieved remarkable performance by integrating the complementary information of views, it is inefficient when facing scalable data. Proverbially, anchor strategy can mitigate such a challenge a certain extent. However, the unsupervised dynamic strategy usually cannot obtain the optimal anchors for MVC. The main reasons are that it does not consider the fairness of different views and lacks the priori supervised guidance. To completely solve these problems, we first propose the priori anchor graph regularization (PAGG) for scalable multi-view bipartite graph clustering, dubbed as SMGC method. Specifically, SMGC learns a few representative consensus anchors to simulate the numerous view data well, and constructs a bipartite graph to bridge the affinities between the anchors and original data points. In order to largely improve the quality of anchors, PAGG predefines prior anchor labels to constrain the anchors with discriminative cluster structure and fair view allocation, such that a better bipartite graph can be obtained for fast clustering. Experimentally, abundant of experiments are accomplished on six scalable benchmark datasets, and the experimental results fully demonstrate the effectiveness and efficiency of our SMGC.

This paper address the problem of optical expansion (OE). OE describes the object scale change between two frames, widely used in monocular 3D vision tasks. Previous methods estimate optical expansion mainly from optical flow results, but this two-stage architecture makes their results limited by the accuracy of optical flow and less robust. To solve these problems, we propose the concept of 3D optical flow by integrating optical expansion into the 2D optical flow, which is implemented by a plug-and-play module, namely TPCV. TPCV implements matching features at the correct location and scale, thus allowing the simultaneous optimization of optical flow and optical expansion tasks. Experimentally, we apply TPCV to the RAFT optical flow baseline. Experimental results show that the baseline optical flow performance is substantially improved. Moreover, we apply the optical flow and optical expansion results to various dynamic 3D vision tasks, including motion-in-depth, time-to-collision, and scene flow, often achieving significant improvement over the prior SOTA. Code is available at https://github.com/HanLingsgjk/TPCV.

In practical scenarios, partial missing of multi-view data is very common, such as register information missing from social network analysis, which results in incomplete multi-view clustering (IMVC). How to fill missing data fast and efficiently plays a vital role in improving IMVC, carrying a significant challenge. Existing IMVC methods always use all observed data to fill in missing data, resulting in high complexity and poor imputation quality due to a lack of guidance from consistent distribution. To break the existing limitations, we propose a novel Distribution Consistency based Fast Anchor Imputation for Incomplete Multi-view Clustering (DCFAI-IMVC) method. Specifically, to eliminate the interference of redundant and fraudulent features in the original space, incomplete data are first projected into a consensus latent space, where we dynamically learn a small number of anchors to achieve fast and good imputation. Then, we employ global distribution information of the observed embedding representations to further ensure the consistent distribution between the learned anchors and the observed embedding representations. Ultimately, a tensor low-rank constraint is imposed on bipartite graphs to investigate the high-order correlations hidden in data. DCFAI-IMVC enjoys linear complexity in terms of sample number, which gives it great potential to handle large-scale IMVC tasks. By performing extensive experiments, our effectiveness, superiority, and efficiency are all validated on multiple public datasets with recent advances.

Due to significant advantages in terms of storage cost and query speed, hashing learning has attracted much attention for image retrieval. Existing hashing methods often acquiescently use long hash codes to guarantee performance, which greatly limits flexibility and scalability. Nevertheless, short hash codes are more suitable for devices with limited computing resources. When these methods use extremely short hash codes, it is difficult to meet the actual performance demand due to the information loss caused by the avalanche of dimension truncation. To address this issue, we propose a novel stepwise refinement short hashing (SRSH) for image retrieval that extracts critical features from high-dimensional image data to learn high-quality hash codes. Specifically, we propose a three-step coupled refinement strategy to relax a single hash function into three more flexible mapping matrices, such that the hash function can have more flexible to approximate precise hash codes and alleviate the information loss. Then, we adopt pairwise similarity preserving to promote coarse and fine hash codes to inherit intrinsic semantic structure from original data. Extensive experiments demonstrate the superior performance of SRSH on four image datasets.

Adversarial attacks in visual object tracking aim to drop tracking performance through injecting imperceptible perturbations to the input of the tracker. Current methods usually superimpose perturbation maps on the input images, and advocate blinding the tracker via occluding the real targets to achieve attack effect. From the perspective of attraction, we alternatively propose a novel idea of attacking the tracker, which advocates using perturbation patches to act as fake targets to attract the tracker's attention. For this purpose, we establish a multi-conditional objective function to generate our ideal patch in an offline iterative manner. For invisibility, we integrate the constraint of patch value into the function for unified optimization. For universality, in addition to adopting large-scale and high-diversity training samples , we also incorporate the video-agnostic condition into this function. To make the patch attractive like a fake target, we elaborately design the non-overlapping area to determine the patch position, and generate matched fake labels to mislead the tracker to track the patch. In online attacking, it only needs to paste the optimized patch onto the video frames, the tracker will be successfully attracted by our patch, achieving attack effect. Extensive experimental results on 8 popular tracking datasets demonstrate that our method can obtain exceptional attack performance in both non-targeted and targeted attack. Additionally, the experiments on transferability illustrate our optimized patches can be directly applied to other trackers with different architectures.

Due to the strong non-linear fitting ability of deep neural networks, deep multi-view clustering has become a popular topic in the fields of signal processing and machine learning. Multi-view clustering based on deep auto-encoder can effectively capture the nonlinear features of high-dimensional data. However, the existing methods still have the following problems: 1) most autoencoder-based deep multi-view clustering methods ignore the differences between cross-view data and lose view-diversity features by using the same encoder structure for different views, and 2) many current deep multi-view techniques rely on single-lane neural networks for extracting feature data from each view. The current approach has limitations in its capability to accurately analyze comprehensive complementary information and multilevel features. To address these issues, we introduce a new clustering method Architecture Alternative Deep Multi-view Clustering (AADMC). Specifically, AADMC proposes a dynamic encoder network to adapt the encoder structure of each view according to the diversities of different views. Subsequently, AADMC proposes utilizing the HilbertSchmidt Independent Criterion (HSIC) to analyze the diversity of information between each encoder output. Moreover, AADMC integrates high-order and low-order information of the data into a shared connection matrix. To be more specific, the lowrank constraint is employed in order to effectively investigate and utilize the consensus information derived from all available views. The effectiveness and superiority of AADMC are demonstrated through experimental results conducted on various public datasets.

Graph-based clustering has become an active topic due to the efficiency in characterizing the relationships between the samples via graph. To improve the quality of graph, recent works propose to utilize global and local information. However, existing methods may lead to a degenerated graph when facing noisy and uneven distributed data. Since 1) they preserve the local information by referring the similarity between each sample-pair, whose confidence is easily disturbed by the poor quality samples; and 2) although the global information is relatively robust to the noisy, existing methods have island effect that lies between local and global structures learning, such that the information of both can not be utilized mutually. To alleviate these issues, this paper presents explicit local coupling global structure clustering (ELGSC) to explicitly learn the local structure and global structure information via a coupling scheme. To be specific, we learn$l(\ll n)$pseudo samples as the anchors to reflect local hot spots distribution, where$n$is the number of samples. By referring the relationship between each anchor-sample pair, ELGSC is capable of obtaining an effective local bipartite graph to capture the local structure. Meanwhile, the self-expressiveness learning is adopted to pursue a lower-rank global affinity graph. Finally, a higher-order coupling learning framework is proposed to couple the learning of global affinity graph and local bipartite graph. Thus, local and global structure information could be propagated each other on both graphs. The experimental results on real datasets demonstrate the efficacy of the proposed method over state-of-the-arts.

Existing multi-kernel clustering (MKC) methods usually focus on constructing a fixed dimension consensus-partition from base kernels to demonstrate their superior in integrating complementary information. Despite their success, they still suffer from the following limitations: (1) The size of consensus-partition is always fixed as the upper bound ($k=n$) or lower bound ($k=c$), where$n$,$c$, and$k$are the number of samples, clusters, and partition dimension, respectively, resulting in suboptimal partition;(2)The learned consensus-partition cannot make full use of the global distribution information hidden in data. To address these issues, we propose a latent consensus-partition learning framework for MKC, namelyConsensus Cluster Center Guided Latent Multi-kernel Clustering(C3LMC), including two methods,i.e., C3LMCKand C3LMCH. For C3LMCK, we flexibly search for a more proper dimension of consensus-partition in a latent embedding space rather than the fixed partition dimension. Meanwhile, the generation of latent consensus-partition is guided by a consensus cluster center of base kernels, such that global distribution information hidden in base kernels can be captured fully. However, C3LMCKsuffers from$\boldsymbol {\mathcal {O}}(n^{2})$computational complexity and memory complexity. Thus, we further propose C3LMCHto handle large-scale data by reducing both kinds of complexities to$\boldsymbol {\mathcal {O}}(n)$. Two solvers with convergence proof are developed to validate our effectiveness, superiority, and efficiency on multiple public datasets with the recent advances.

Adversarial attacks in visual object tracking aims to fool trackers via injecting invisible perturbations for the video frames. Most adversarial methods advocate generating perturbations for each video frame, but frequent attacks may increase the computational load and the risk of exposure. Unfortunately, less works are about only attacking the initial frame and their attack effects are insufficient. To tackle this, we focus on the initialization phase of tracking and propose an only once attack framework. It can effectively fool the tracker via only generating invisible perturbations for the initial template, rather than each frame. Specifically, considering the tracking mechanism of the Siamese-based trackers, we design the minimum score-based and the minimum IoU-based loss functions. Both of them are used for training the UNet-based perturbation generator instead of the tracker, achieving the non-targeted attack. Additionally, we propose the location and direction offsets as the base attacks of sophisticated targeted attack. Combined with the two basic attacks, the tracker can be easily hijacked to move towards the fake target predefined by users. Extensive experimental results demonstrate that our only once attack framework costs the least number of attacks yet achieves better attack effect, with the maximum drop of 68.7%. The transferability experiments illustrate that our attack framework with good generalization ability can be directly applicable to the CNN-based, Siamese-based, deep discriminative-based and Transformer-based trackers, without retraining.

With the development of video network, image set classification (ISC) has received a lot of attention and can be used for various practical applications, such as video based recognition, action recognition, and so on. Although the existing ISC methods have obtained promising performance, they often have extreme high complexity. Due to the superiority in storage space and complexity cost, learning to hash becomes a powerful solution scheme. However, existing hashing methods often ignore complex structural information and hierarchical semantics of the original features. They usually adopt a single-layer hashing strategy to transform high-dimensional data into short-length binary codes in one step. This sudden drop of dimension could result in the loss of advantageous discriminative information. In addition, they do not take full advantage of intrinsic semantic knowledge from whole gallery sets. To tackle these problems, in this paper, we propose a novel Hierarchical Hashing Learning (HHL) for ISC. Specifically, a coarse-to-fine hierarchical hashing scheme is proposed that utilizes a two-layer hash function to gradually refine the beneficial discriminative information in a layer-wise fashion. Besides, to alleviate the effects of redundant and corrupted features, we impose the $\ell _{2,1}$ norm on the layer-wise hash function. Moreover, we adopt a bidirectional semantic representation with the orthogonal constraint to keep intrinsic semantic information of all samples in whole image sets adequately. Comprehensive experiments demonstrate HHL acquires significant improvements in accuracy and running time. We will release the demo code on https://github.com/sunyuan-cs.

Modeling a sequence of video frames as a linear subspace on Grassmann manifold has recently become increasingly attractive in multiple computer vision applications. The success of such algorithms largely depends on a good distance measure, and learning an appropriate metric on Grassmann manifold remains a key challenge. Existing works address this by learning a discriminative mapping from the original Grassmann manifold to Hilbert space or a lower-dimensional, more discriminative Grassmann manifold. However, these approaches always highly rely on nearest neighbor matching of samples on the projected space, which is sensitive to noises and errors. Different from them, this paper proposes a Grassmann Reconstruction Metric Learning (GRML) algorithm guided by sparse representation-based classifier (SRC) for image set classification. SRC selects the coefficients associated with each class to reconstruct training samples, and then we employ it as a criterion to direct the design of a discriminant metric on Grassmann manifold. Specifically, GRML attempts to jointly maximize the inter-class reconstruction residual and minimize the intra-class reconstruction residual in the lower but more discriminative Grassmann manifold. To further explore the intrinsic geometry distance, we present a Grassmann Reconstruction Multiple Kernel Metric Learning (GRMKML) algorithm, which aims to jointly learn a metric and the corresponding kernel from a family of kernels for Grassmann manifold. Extensive experiments on eight benchmark datasets demonstrate that the proposed algorithms perform favorably against the state-of-the-art methods.

As a challenging visual task, visual object tracking has recently been composed of the classification and regression subtasks. The anchor-free regression network gets rid of the dependence on the anchors, but the redundant range makes it usually regress some samples involving non-target information. Evenly dividing a target by the regular receptive field often causes ambiguous target localization. To address these issues, we propose a regression-selective feature-adaptive tracker (RSFA), where the regression-selective subnetwork can not only free the regression task from anchors, but can also select more effective regression samples using the refined criterion. The proposed feature-adaptive strategy concentrates the classification subnetwork on target feature extraction via adaptively modifying the receptive field, and the attached centrality branch offers a correction for target localization by exploiting the spatial information. Additionally, the designed online update mechanism realizes the tracker's online optimization, improving robustness against target deformation. Extensive experiments are conducted on challenging benchmarks, including GOT10 K, OTB2015, UAV123, NFS, VOT2018, VOT2019 and VOT2020-ST. Our tracker achieves satisfactory tracking results, and the evaluations of its tracking performance rank first or second in comparison with the state-of-the-art tracking algorithms.

Incomplete multi-view clustering (IMVC) is deemed a significant research topic in multimedia to handle data loss situations. Current late fusion incomplete multi-view clustering methods have attracted intensive attention owing to their superiority in using consensus partition for effective and efficient imputation and clustering. However, 1) their imputation quality and clustering performance depend heavily on the static prior partition, such as predefined zeros filling, destroying the diversity of different views; 2) the size of base partitions is too small, which would lose advantageous details of base kernels to decrease clustering performance. To address these issues, we propose a novel IMVC method, named Dynamic Incomplete Multi-view Imputing and Clustering (DIMIC). Concretely, the observed views dynamically generate a consensus proxy with the guidance of a shared cluster matrix for more effective imputation and clustering, rather than a fixed predefined partition matrix. Furthermore, the proper size of base partitions is employed to protect sufficient kernel details for further enhancing the quality of the consensus proxy. By designing a solver with a linear computational and memory complexity on extensive experiments, our effectiveness, superiority, and efficiency are validated on multiple public datasets with recent advances.

This paper addresses the problem of normalized scene flow (NSF): given a pair of RGB video frames, estimating the 3D motion, which consisted of optical flow and motion-in-depth estimation. NSF is a powerful tool for action prediction and autonomous robot navigation, presenting the advantage of only needing a monocular and uncalibrated camera. However, most existing methods directly regress motion-in-depth from two RGB frames or optical flow, resulting in sub-accurate and non-robust results. Our key insight is the scale matching scheme-establishing correlations between two frames containing objects in different scales, to estimate dense and continuous motion-in-depth. Based on the scale matching, we propose a unified framework: Scale-flow, which combines scale matching and optical flow estimation. This combination makes optical flow estimation can use dense and continuous scale information for the first time, so that the moving foreground objects can be estimated more accurately. On KITTI, our monocular approach achieves the lowest error in the foreground scene flow task, even compared with the multi-camera method. Moreover, on the motion-in-depth estimation task, Scale-flow reduces the error by 34% compared with the best-published method. Code will be available.

Image set classification (ISC) has always been an active topic, primarily due to the fact that image set can provide more comprehensive information to describe a subject. However, the existing ISC methods face two problems: (1) The high computational cost prohibits these methods from being applied into median or large-scale applications; (2) the consensus information between feature and semantic representation of image set are largely ignored. To overcome these issues, in this paper, we propose a novel ISC method, termly feature and semantic views consensus hashing (FSVCH). Specifically, a kernelized bipartite graph is constructed to capture the nonlinear structure of data, and then two-views (\ie feature and semantic) consensus hashing learning (TCHL) is proposed to obtain a shared hidden consensus information. Meanwhile, for robust out-of-sample prediction purpose, we further propose TCHL guided optimal hash function inversion (TGHI) to learn a high-quality general hash function. Afterwards, hashing rotating (HR) is employed to obtain a more approximate real-valued hash solution. A large number of experiments show that FSVCH remarkably outperforms comparison methods on three benchmark datasets, in term of running time and classification performance. Experimental results also indicate that FSVCH can be scalable to median or large-scale ISC task.

Multiple kernel clustering (MKC) has demonstrated promising performance for handing non-linear data clustering. Positively, it can integrate complementary information of multiple base kernels and avoid kernel function selection. However, negatively, the main challenging is that the kernel matrix with the size n x n leads to O(n2) memory complexity and O(n3) computational complexity. To mitigate such a challenging, taking graph Laplacian as breakthrough, this paper proposes a novel and simple MKC method, dubbed as approximate shifted Laplacian reconstruction (ASLR). For each base kernel, we propose the r-rank shifted Laplacian reconstruction scheme by considering the energy losing of Laplacian reconstruction and the clustering information preserving of Laplacian decompose simultaneously. Then, by analyzing the eigenvectors of the reconstructed Laplacian, we impose some constrains to tame its solution within a Fantope. Accordingly, the byproduct (i.e. the most informative eigenvectors) contains the main clustering information, such that the clustering assignments can be obtained relying on simple k-means algorithm. Owe to the Laplacian reconstruction scheme, the memory and computational complexity can be reduced to O(n) and O<(n^2)$, respectively. As experimentally demonstrated on eight challenging MKC benchmark datasets, the results verify the effectiveness and efficiency of ASLR.

Kernel k-means (KKM) and spectral clustering (SC) are two basic methods used for multiple kernel clustering (MKC), which have both been widely used to identify clusters that are non-linearly separable. However, both of them have their own shortcomings: 1) the KKM-based methods usually focus on learning a discrete clustering indicator matrix via a combined consensus kernel, but cannot exploit the high-order affinities of all pre-defined base kernels; and 2) the SC-based methods require a robust and meaningful affinity graph in kernel space as input in order to form clusters with desired clustering structure. In this paper, a novel method, kernel k-means coupled graph tensor (KCGT), is proposed to graciously couple KKM and SC for seizing their merits and evading their demerits simultaneously. In specific, we innovatively develop a new graph learning paradigm by leveraging an explicit theoretical connection between clustering indicator matrix and affinity graph, such that the affinity graph propagated from KKM enjoys the valuable block diagonal and sparse property. Then, by using this graph learning paradigm, base kernels can produce multiple candidate affinity graphs, which are stacked into a low-rank graph tensor for capturing the high-order affinity of all these graphs. After that, by averaging all the frontal slices of the tensor, a high-quality affinity graph is obtained. Extensive experiments have shown the superiority of KCGT compared with the state-of-the-art MKC methods.

Next-generation wireless networks are witnessing an increasing number of clustering applications, and produce a large amount of non-linear and unlabeled data. In some degree, single kernel methods face the challenging problem of kernel choice. To overcome this problem for non-linear data clustering, multiple kernel graph-based clustering (MKGC) has attracted intense attention in recent years. However, existing MKGC methods suffer from two common problems: (1) they mainly aim to learn a consensus kernel from multiple candidate kernels, slight affinity graph learning, such that cannot fully exploit the underlying graph structure of non-linear data; (2) they disregard the high-order correlations between all base kernels, which cannot fully capture the consistent and complementary information of all kernels. In this paper, we propose a novel non-negative matrix factorization (NMF) tailored graph tensor MKGC method for non-linear data clustering, namely TMKGC. Specifically, TMKGC integrates NMF and graph learning together in kernel space so as to learn multiple candidate affinity graphs. Afterwards, the high-order structure information of all candidate graphs is captured in a 3-order tensor kernel space by introducing tensor singular value decomposition based tensor nuclear norm, such that an optimal affinity graph can be obtained subsequently. Based on the alternating direction method of multipliers, the effective local and distributed solvers are elaborated to solve the proposed objective function. Extensive experiments have demonstrated the superiority of TMKGC compared to the state-of-the-art MKGC methods.

Significant attention to multiple kernel graph-based clustering (MKGC) has emerged in recent years, primarily due to the superiority of multiple kernel learning (MKL) and the outstanding performance of graph-based clustering. However, many existing MKGC methods design a fat model that poses challenges for computational cost and clustering performance, as they learn both an affinity graph and an extra consensus kernel cumbersomely. To tackle this challenging problem, this article proposes a new MKGC method to learn a consensus affinity graph directly. By using the self-expressiveness graph learning and an adaptive local structure learning term, the local manifold structure of the data in kernel space is preserved for learning multiple candidate affinity graphs from a kernel pool first. After that, these candidate affinity graphs are synthesized to learn a consensus affinity graph via a thin autoweighted fusion model, in which a self-tuned Laplacian rank constraint and a top- k neighbors sparse strategy are introduced to improve the quality of the consensus affinity graph for accurate clustering purposes. The experimental results on ten benchmark datasets and two synthetic datasets show that the proposed method consistently and significantly outperforms the state-of-the-art methods.

In the cognitive computing of intelligent industrial Internet of Things, clustering is a fundamental machine learning problem to exploit the latent data relationships. To overcome the challenge of kernel choice for nonlinear clustering tasks, multiple kernel clustering (MKC) has attracted intensive attention. However, existing graph-based MKC methods mainly aim to learn a consensus kernel as well as an affinity graph from multiple candidate kernels, which cannot fully exploit the latent graph information. In this article, we propose a novel pure graph-based MKC method. Specifically, a new graph model is proposed to preserve the local manifold structure of the data in kernel space so as to learn multiple candidate graphs. Afterward, the latent consistency and selfishness of these candidate graphs are fully considered. Furthermore, a graph connectivity constraint is introduced to avoid requiring any postprocessing clustering step. Comprehensive experimental results demonstrate the superiority of our method.

Multiple kernel learning (MKL) is generally recognized to perform better than single kernel learning (SKL) in handling nonlinear clustering problem, largely thanks to MKL avoids selecting and tuning predefined kernel. By integrating the self-expression learning framework, the graph-based MKL subspace clustering has recently attracted considerable attention. However, the graph structure of data in kernel space is largely ignored by previous MKL methods, which is a key concept of affinity graph construction for spectral clustering purposes. In order to address this problem, a novel MKL method is proposed in this article, namely, structure-preserving multiple kernel clustering (SPMKC). Specifically, SPMKC proposes a new kernel affine weight strategy to learn an optimal consensus kernel from a predefined kernel pool, which can assign a suitable weight for each base kernel automatically. Furthermore, SPMKC proposes a kernel group self-expressiveness term and a kernel adaptive local structure learning term to preserve the global and local structure of the input data in kernel space, respectively, rather than the original space. In addition, an efficient algorithm is proposed to solve the resulting unified objective function, which iteratively updates the consensus kernel and the affinity graph so that collaboratively promoting each of them to reach the optimum condition. Experiments on both image and text clustering demonstrate that SPMKC outperforms the state-of-the-art MKL clustering methods in terms of clustering performance and computational cost.

The hardware realization of Universal Filtered Multi Carrier (UFMC) architecture has attracted significant attention in fifth generation (5G) and beyond. In addition to the flexibility in fast Fourier transform (FFT)-length, a flexible prototype filter in combination with multiplicative complex spectrum shifting co-efficients is required for realizing flexible UFMC architecture. The existing architectures of UFMC transmitter commonly adopted fixed-size FFT-length, number of subbands, subband size, and filter-length. Moreover, the lack of flexible prototype filter and spectrum localization of filter co-efficients to individual subbands limits the flexible UFMC system design. In this paper, we propose VLSI architecture for a flexible length prototype filter that can generate spectrally shifted filter co-efficients to individual subbands in tune with the changing value of FFT-length, number of subbands, subband size, and filter-length. For 16-bit word size architecture, our proposed design produces filter co-efficients and spectrum shifting co-efficients upto length,$2^{15}$. Thus, any desired combination of FFT-length, number of subbands, subband size and filter-length is selected to generate the filter co-efficients for the individual subbands. Moreover, complex multiplication and addition operations are reduced in proposed architecture, quantitatively, about 58.81% reduction in filtering unit is achieved over the state-of-the-art architecture. Finally, hardware implementation output and XILINX post route simulation result matches perfectly with MATLAB simulations.

Average consensus theory is intensely popular for building time synchronization in wireless sensor network (WSN). However, the average consensus-based time synchronization algorithm is based on the iteration that poses challenges for efficiency, as they entail high communication cost and long convergence time in large-scale WSN. Based on the suggestion that the greater the algebraic connectivity the faster the convergence, a novel multihop average consensus time synchronization (MACTS) is developed with innovative implementation in this article. By employing multihop communication model, it shows that virtual communication links among multihop nodes are generated and algebraic connectivity of the network increases. Meanwhile, a multihop controller is developed to balance the convergence time, accuracy, and communication complexity. Moreover, the accurate relative clock offset estimation is yielded by delay compensation. Implementing the MACTS based on the popular one-way broadcast model and taking multihop over short distances, we achieve hundreds of times the MACTS convergence rate compared to average TimeSync (ATS).

To defy the curse of dimensionality, the inputs are always projected from the original high-dimensional space into the target low-dimension space for feature extraction. However, due to the existence of noise and outliers, the feature extraction task for corrupted data is still a challenging problem. Recently, a robust method called low rank embedding (LRE) was proposed. Despite the success of LRE in experimental studies, it also has many disadvantages: 1) The learned projection cannot quantitatively interpret the importance of features. 2) LRE does not perform data reconstruction so that the features may not be capable of holding the main energy of the original “clean” data. 3) LRE explicitly transforms error into the target space. 4) LRE is an unsupervised method, which is only suitable for unsupervised scenarios. To address these problems, in this paper, we propose a novel method to exploit the latent discriminative features. In particular, we first utilize an orthogonal matrix to hold the main energy of the original data. Next, we introduce an 12,1-norm term to encourage the features to be more compact, discriminative and interpretable. Then, we enforce a columnwise 12,1-norm constraint on an error component to resist noise. Finally, we integrate a classification loss term into the objective function to fit supervised scenarios. Our method performs better than several state-of-the-art methods in terms of effectiveness and robustness, as demonstrated on six publicly available datasets.

Subspace clustering plays an important role in the tasks such as data processing and pattern recognition. Since the high-dimensional data may contain complex noise, as well as non-linear structure, learning low-dimensional subspace structures is a challenging task. However, the existing methods to deal with both problems relax the original problem convexly. The results of solving by these methods deviate from the solution of the original problem. In this paper, to overcome this deficiency, we propose a robust low-rank kernel subspace clustering model, which coalesces the non-convex Schatten p-norm (0 <; p ≤ 1) regularizer with “kernel trick” and correntropy. Our “kernel trick” extends linear subspace clustering to non-linear counterparts, the Schatten p-norm regularizer can approximate the rank of the data in feature space effectively, and the correntropy is a robust measure to large corruptions. Furthermore, an efficient iterative algorithm (HQ-ADMM) is designed to solve the formulated problem, which coalesces the half-quadratic technique and Alternating Direction Method of Multipliers. This algorithm can ensure the closed form solutions at each iteration, which improves the computation speed of the algorithm. Extensive experiments on face/object clustering and motion segmentation clearly attest the ascendancy of the proposed method over several state-of-the-art methods.