Finger vein recognition is an emerging biometric technology with high security and various application scenarios. Most finger vein recognition methods are based on a single view. However, the inherent problems in single-view finger vein recognition, such as limited feature, sensitivity to finger translation and rotation, and the ambiguity issue in 2D projections, hinder the improvement of the system performance. To address these problems and enhance finger vein verification performance, we employ multi-view finger vein images that are capable of providing a more comprehensive feature of 3D finger vein. Specifically, we design a novel low-cost full-view finger vein imaging device that enables full-view capture of finger veins with only a single camera and establish a multi-view finger vein dataset, named THU-MVFV. In addition, we propose a Multi-view Finger Vein Feature Encoding and Selection Network (MFV-FESNet), which is based on an improved Transformer encoder that can learn the dependencies between different views. By fusing the extracted global context feature and local dominant feature, the network can generate a feature descriptor with high discrimination. Extensive experiments are conducted on THU-MVFV and demonstrate the superior performance of the proposed model. The THU-MVFV dataset will be publicly available athttps://github.com/Finger-Vein-Dataset/THU-MVFV.

Since hand-print recognition, i.e., palmprint, finger-knuckle-print (FKP), and hand-vein, have significant superiority in user convenience and hygiene, it has attracted greater enthusiasm from researchers. Seeking to handle the long-standing interference factors, i.e., noise, rotation, shadow, in hand-print images, multi-view hand-print representation has been proposed to enhance the feature expression by exploiting multiple characteristics from diverse views. However, the existing methods usually ignore the high-order correlations between different views or fuse very limited types of features. To tackle these issues, in this paper, we present a novel tensorized multi-view low-rank approximation based robust hand-print recognition method (TMLA_RHR), which can dexterously manipulate the multi-view hand-print features to produce a high-compact feature representation. To achieve this goal, we formulate TMLA_RHR by two key components, i.e., aligned structure regression loss and tensorized low-rank approximation, in a joint learning model. Specifically, we treat the low-rank representation matrices of different views as a tensor, which is regularized with a low-rank constraint. It models the across information between different views and reduces the redundancy of the learned sub-space representations. Experimental results on eight real-world hand-print databases prove the superiority of the proposed method in comparison with other state-of-the-art related works.

Low-quality palmprint images will degrade the recognition performance, when they are captured under the open, unconstraint, and low-illumination conditions. Moreover, the traditional single-view palmprint representation methods have been difficult to express the characteristics of each palm strongly, where the palmprint characteristics become weak. To tackle these issues, in this article, we propose a structure suture learning-based robust multiview palmprint recognition method (SSL_RMPR), which comprehensively presents the salient palmprint features from multiple views. Unlike the existing multiview palmprint representation methods, SSL_RMPR introduces a structure suture learning strategy to produce an elastic nearest neighbor graph (ENNG) on the reconstruction errors that simultaneously exploit the label information and the latent consensus structure of the multiview data, such that the discriminant palmprint representation can be adaptively enhanced. Meanwhile, a low-rank reconstruction term integrating with the projection matrix learning is proposed, in such a manner that the robustness of the projection matrix can be improved. Particularly, since no extra structure capture term is imposed into the proposed model, the complexity of the model can be greatly reduced. Experimental results have proven the superiority of the proposed SSL_RMPR by achieving the best recognition performances on a number of real-world palmprint databases.

In this article, we propose a novel and effective incomplete multi-view clustering (IMVC) framework, referred to as incomplete multi-view clustering with regularized hierarchical graph (IMVC_RHG). Different from the existing graph learning-based IMVC methods, IMVC_RHG introduces a novel heterogeneous-graph learning and embedding strategy, which adopts the high-order structures between four tuples for each view, rather than a simple paired-sample intrinsic structure. Besides this, with the aid of the learned heterogeneous graphs, a between-view preserving strategy is designed to recover the incomplete graph for each view. Finally, a consensus representation for each sample is gained with a co-regularization term for final clustering. As a result of integrating these three learning strategies, IMVC_RHG can be flexibly applied to different types of IMVC tasks. Comparing with the other state-of-the-art methods, the proposed IMVC_RHG can achieve the best performances on real-world incomplete multi-view databases.

Finger vein recognition has received more attention in recent years due to its high security and promising development potential. However, extracting complete vein patterns and obtaining features from the original images suffer from the low contrast of finger vein images, which dramatically restrains the performance of finger vein recognition algorithms. Inspired by this motivation, we propose an explicit and implicit feature fusion Network (EIFNet) for finger vein verification. It can extract more comprehensive and discriminative features by complementarily fusing the features extracted from binary vein masks and gray original images. We design a feature fusion module (FFM) acting as a bridge between mask feature extraction module (MFEM) and contextual feature extraction module (CFEM) to achieve the optimal fusion of features. To obtain more accurate vein masks, we develop a novel finger vein pattern extraction method and provide the first finger vein segmentation dataset THUFVS. We solve the difficulty of building finger vein segmentation datasets in a simple but effective way, and develop a complete process encompassing dataset creation, data augmentation refinement and network design, which refers to the Mask Generation Module (MGM), for the deep learning based finger vein pattern extraction method. Experimental results demonstrate the superior verification performance of EIFNet on three widely used datasets compared with other existing methods.

Preserving projection learning has been widely used in feature extraction and selection for unsupervised image classification. Generally, some related methods constructed a graph to represent the nearest neighbor relationships of the data based on the Euclidean distances among different samples, which used 0 or 1 to predefine whether two samples are from the same class. Since a simple Euclidean distance is sensitive to noise, the predefined graph cannot produce exact correlations between the two samples. What is more, the predefined graph cannot reflect the structure of the projected data on a latent subspace when the projection matrix is learned. To solve these problems, in this article a novel adaptive graph embedded preserving projection learning (AGE_PPL) method is proposed, first combining the sparsity-based graph learning and the projection learning as an integral framework for feature extraction and feature selection. In particular, a sparse representation term with$l_{1}$-norm is exploited in AGE_PPL to achieve the adaptive graph of the data to preserve the local structures among different samples while the projection matrix is learned. Meanwhile, a global-scale constraint is imposed to preserve the global structure of the data on a latent subspace. Therefore, the transformed samples will be more discriminative, allowing margins of the same class to be reduced, and margins among different classes to be enlarged. Experimental results proved the effectiveness of the proposed algorithm by obtaining competitive performances over other baseline and state-of-the-art methods. In addition, the proposed method is very flexible for feature selection and dimensionality reduction.

The main focus of most existing face hallucination methods is to generate visually pleasing results. However, in many applications, the final goal is to identify the person in the low-resolution (LR) image. In this paper, we propose a texture and identity integration network (TIIN) to effectively incorporate identity information into face hallucination tasks. TIIN consists of an identity-preserving denormalization module (IDM) and an equalized texture enhance module (ETEM). The IDM exploits the identity prior and the ETEM improves image quality through histogram equalization. To extract identity information effectively, we propose a resolution-robust identity knowledge distillation network (RIKDN). RIKDN is specifically designed for LR face recognition and can be of independent interest. It employs two teacher-student streams. One stream narrows the performance gap between high-resolution (HR) and LR images. The other distills correlation information from the HR-HR teacher stream to guide learning in the LR-HR student stream. We conduct extensive experiments on multiple datasets to demonstrate the effectiveness of our methods.

The finger vein trait has attracted widespread attention for personal authentication in recent years. However, most finger vein verification methods are performed on the single perspective, captured by a monocular near-infrared camera fixed at one side of the finger. Consequently, the contents of a single perspective have few details of the spatial network structure of the finger vein and show noticeable differences even if the posture of the same finger is slightly different. Both of them impact the verification performance. Hence, finger vein images captured from different viewpoints are considered in this work. We first design a low-cost multi-perspective based dorsal finger vein imaging device for data collection. A deep neural network named Hierarchical Content-Aware Network (HCAN) is then proposed to extract the discriminative hierarchical features of the finger vein. Specifically, HCAN is compound of a Global Stem Network (GSN) and a Local Perception Module (LPM). GSN aims to extract the latent global 3D feature from all perspectives through a recurrent neural network. It enables the model to retain the details in previous hidden states by incorporating a memory weighting strategy. LPM is designed to perceive each perspective from the aspect of image entropy. Guided by the entropy loss, LPM captures the prominent local feature and improves the discriminability and robustness of the hierarchical feature. The experimental results on the newly collected THU-MFV database demonstrate the superiority of the proposed method in comparison with other multi-perspective and single-perspective based methods.