The quality problem of finger vein image largely affects the finger vein recognition performance. In order to precisely select the high-quality images, this paper proposes a reverse attention-based multi-feature interaction network for finger vein image quality evaluation. In the proposed network, the reverse attention module is used in two identical branches to extract the quality features from grayscale finger vein image and its binary vein pattern image. Additionally, the quality features from each branch is enhanced by interacting with the quality features from another branch in the proposed interaction module. Finally, the compact bilinear pooling performs the product fusion of two kinds of enhanced quality features and reduces the dimensionality of the fused features. We manually and algorithmically label the image quality of the open finger vein database from Shandong University. The classification accuracies of the proposed network are 91.67% and 86.67% on the quality-labeled images, which is superior to the performance of the state-of-the-art methods.

Recently, finger vein sensors have been embedded in all kinds of electronic devices for personal identification, such as intelligent door locks and attendance machines. The embedded sensors are generally small, thus capturing only part of the finger vein. However, prior studies have focused on near-full finger vein recognition, without considering the partial finger vein image caused by the small imaging window of the finger vein sensor. This paper aims to study personal identification based on partial finger vein images, known as small-area finger vein recognition. The effect of the small-area finger vein on recognition performance is first analyzed by cutting out the local part from the near-full finger vein image to model a small-area finger vein image. Second, a small-area finger vein database is built using a commercial finger vein imaging device, in which the vein pattern from approximately one-third of one adult finger is captured. To explore more discriminative information from small-area finger vein images, we propose a locality-constrained consistent dictionary learning (LCDL) method to fuse multiple features for small-area finger vein recognition. Finally, the proposed method is evaluated on the self-built small-area finger vein database and four synthetic small-area finger vein databases. Experimental results show the promising recognition performance of the proposed method.

Zero-shot hashing targets to learn the hash codes of images in unseen classes based on the limited training data provided by seen classes. In zero-shot hashing, transferring the supervised knowledge, such as attributes and semantic relations, from seen classes to unseen ones is a widely employed method, where the performance is always subject to the ability to capture these supervised knowledge (which is always difficult to obtain). Therefore, in this study, we propose a new methodology for zero-shot hashing via an asymmetric ratio similarity matrix (ASZH), which only needs to calculate the semantic similarity among seen classes for hash learning. Specifically, we use an asymmetric ratio matrix in the similarity calculation to further explore the influence of similarity, where the values of positive weights for similar samples are not equivalent to those of negative ones for dissimilar samples. Additionally, a theoretical analysis regarding the utilization of an asymmetric ratio matrix is provided in this study. The experiments on three large benchmark datasets indicate that the proposed method achieves excellent performance than several state-of-the-art hashing methods.

In recent years, Electrocardiogram (ECG) biometrics has gained extensive attention. However, most existing methods adopted offline batch learning, which means that they need to accumulate all data and retrain the model when new data comes. Therefore, it is inefficient and unpractical for them to handle the online scenario where new data may continually come. To overcome the above limitation, we propose a novel ECG biometrics framework, termed Online ECG Biomet-rics based on Hadamard Codes. Firstly, we leverage matrix factorization to learn discriminative representations for ECG signals from their base feature space. Considering to leverage the orthogonal property of the Hadamard matrix, we use it to construct Hadamard codes to represent individuals and further guide the learning of representations. Furthermore, we develop an online optimization algorithm, which is efficient and effective to investigate the incremental problem in the context of ECG biometrics. The experimental results on two benchmark datasets indicate the merits of the proposed framework over the state-of-the-art.

Electrocardiogram (ECG) biometrics has aroused extensive attention in the research field of biometric recognition. How-ever, most existing methods either only consider a single do-main (time domain or frequency domain) to extract features or extract multi-features while ignoring the specific proper-ties of each domain. In this paper, we propose a novel ECG biometrics framework termed Joint Dual-domain Matrix Factorization (JDMF). JDMF learns latent spaces for each do-main by exploring the cross-correlations between them and preserving domain-specific properties. To endow the latent spaces with more powerful representation capabilities, JDMF further makes full use of the supervised information and could automatically learn the weights of domains. The experimental results on two widely-used datasets indicate that the proposed framework can outperform state-of-the-arts.

Electrocardiogram (ECG) biometric recognition has recently attracted considerable attention and various promising approaches have been proposed. However, due to the real nonstationary ECG noise environment, it is still challenging to perform this technique robustly and precisely. In this paper, we propose a novel ECG biometrics framework named robuSt semanTic spacE leaRning with Local sImilarity preserviNG (STERLING) to learn a latent space where ECG signals can be robustly and discriminatively represented with semantic information and local structure being preserved. Specifically, in the proposed framework, a novel loss function is proposed to learn robust semantic representation by introducing l2,1-norm loss and making full use of the supervised information. In addition, a graph regularization is imposed to preserve the local structure information in each subject. Finally, in the learnt latent space, matching can be effectively done. The experimental results on three widely-used datasets indicate that the proposed framework can outperform the state-of-the-arts.

Vein pattern-based methods have powerfully promoted the performance of finger vein recognition. However, it is not easy to precisely extract vein patterns from images, especially from low-quality images, and the non-vein area have been proved to be helpful for recognition. This paper proposes to use low-rank representation to extract as much noiseless discriminative information as possible from finger vein images. However, image deformation and image quality variations weaken the correlation of genuine images, and therefore damage the low-rank linear representation. To further deal with this problem, the class labels of training images and the local geometric structure between testing images and training images, reflected by sparse reconstruction errors of testing images, are used as constraints of low-rank coefficients. In particular, vein backbone decomposition based sparse representation is proposed to fast compute the deformation-robust reconstruction errors of each testing image. The reconstruction errors on sub-backbones of one training image are summed and modified as the constraint of the low-rank coefficient on this training image. We evaluate the proposed method on three widely used finger vein databases, and experimental results show that the proposed method performs well in finger vein recognition.

In second paragraph of the footnote on the first page of[1], the institution information of Lu Yang and Xiaoming Xi is inaccurate. The correct institution name is “School of Computer Science and Technology, Shandong University of Finance and Economics.” So this paragraph should be corrected as:

Vein pattern-based methods powerfully boost the recognition accuracy of finger veins, but real-time recognition cannot be guaranteed, especially in large-scale applications. Moreover, previous studies focused on either the matching task to enhance the accuracy or the indexing task to improve the efficiency. This paper proposes a finger vein code indexing method and combines it with a finger vein pattern matching method into an integration framework for improving both accuracy and efficiency. With the extracted vein patterns, the direction of each vein segment is detected and represented by the elliptical direction map as a feature for indexing, which will be encoded into a binary code by the angle K-means. The similarity between vein direction codes is measured by the grouped hamming distance in indexing, and further weighted by the overlap degree of the corresponding vein patterns to return the candidates for the probe. In addition, based on the above distance measurement, only vein segments with the same direction code are considered in following probe-to-candidate matching. Experimental results indicate that our indexing method outperforms the state-of-the-art methods and has competitive potential in performing the matching task. The results also indicate that the integration framework highly improves the identification efficiency with a slight improvement on the accuracy.

ECG biometrics has achieved great success on high quality ECG signals. However, it is still a challenging problem to apply ECG biometrics on mobile devices due to the low quality signals. In this paper, we propose a robust two-stage model. In first stage, we utilize 1D CNN model to remove the invalid heartbeats from ECG recording. And then, we combine the raw signal with the hidden feature of 1D CNN as the feature representation of heartbeat. In second stage, we group a certain number of heartbeat representations as input sequence. Attention-based bidirectional LSTM is used to aggregate input sequence and generate discriminative identity features for recognition. We evaluate our method on two public datasets, and the results show that our two-stage model can achieve the state-of-the-art performance compared with other existing methods.

Finger vein recognition has received a lot of attention recently and is viewed as a promising biometric trait. In related methods, vein pattern-based methods explore intrinsic finger vein recognition, but their performance remains unsatisfactory owing to defective vein networks and weak matching. One important reason may be the neglect of deep analysis of the vein anatomy structure. By comprehensively exploring the anatomy structure and imaging characteristic of vein patterns, this paper proposes a novel finger vein recognition framework, including an anatomy structure analysis-based vein extraction algorithm and an integration matching strategy. Specifically, the vein pattern is extracted from the orientation map-guided curvature based on the valley- or half valley-shaped cross-sectional profile. In addition, the extracted vein pattern is further thinned and refined to obtain a reliable vein network. In addition to the vein network, the relatively clear vein branches in the image are mined from the vein pattern, referred to as the vein backbone. In matching, the vein backbone is used in vein network calibration to overcome finger displacements. The similarity of two calibrated vein networks is measured by the proposed elastic matching and further recomputed by integrating the overlap degree of corresponding vein backbones. Extensive experiments on two public finger vein databases verify the effectiveness of the proposed framework.

Although some developments have been achieved in finger vein recognition recently, the image deformation problem has received relatively less attention and still intractable. In this paper, the reason and the harmfulness of this problem are analyzed firstly. And then, a deformable finger vein recognition framework is proposed to deal with this problem, consisting of the improved vein PCA-SIFT feature and bidirectional deformable spatial pyramid matching (BDSPM). Furthermore, we build a finger vein deformation database to imitate image deformation in real application. The experimental results, on the self-built deformation database and one public database, prove the effectiveness of the proposed framework for dealing with the image deformation problem.

Efficient identification of finger veins is still a challenging problem due to the increasing size of the finger vein database. Most leading finger vein image identification methods have high-dimensional real-valued features, which result in extremely high computation complexity. Hashing algorithms are extraordinary effective ways to facilitate finger vein image retrieval. Therefore, in this paper, we proposed a finger vein image retrieval scheme based on Affinity-Preserving K-means Hashing (APKMH) algorithm and bag of subspaces based image feature. At first, we represent finger vein image by Nonlinearly Sub-space Coding (NSC) method which can obtain the discriminative finger vein image features. Then the features space is partitioned into multiple subsegments. In each subsegment, we employ the APKMH algorithm, which can simultaneously construct the visual codebook by directly k-means clustering and encode the feature vector as the binary index of the codeword. Experimental results on a large fused finger vein dataset demonstrate that our hashing method outperforms the state-of-the-art finger vein retrieval methods.

Although some image retrieval methods were proposed to accelerate finger vein recognition, the insufficient feature (e.g., the number of vein point) and unfavorable encoding (e.g., predefined threshold based binarization) limited retrieval performance largely. In view of this problem, we develop a new retrieval framework, based on the integration of discriminative texture features and similarity-preserving binary codes. In detail, the vector and scalar features, measuring the gray level, gray difference, and gray gathering of image patch, are both used to represent finger vein image. And to improve the retrieval efficiency, the high-dimensional decimal features are further encoded into the compact binary patterns by principal component analysis (PCA) and similarity-preserving iterative quantization (ITQ). Experimental results on one large finger vein database prove that the proposed method can powerfully improve the retrieval accuracy and efficiency.

Nature Language Processing has been paid more attention recently. Traditional approaches for language model primarily rely on elaborately designed features and complicated natural language processing tools, which take a large amount of human effort and are prone to error propagation and data sparse problem. Deep neural network method has been shown to be able to learn implicit semantics of text without extra knowledge. To better learn deep underlying semantics of sentences, most deepneuralnetworklanguagemodelsutilizemulti-gramstrategy. However, the current multi-gram strategies in CNN framework are mostly realized by concatenating trained multi-gram vectors to form the sentence vector, which can increase the number of parameters to be learned and is prone to over fitting. To alleviate the problem mentioned above, we propose a novel adaptive sentence representation learning model based on multigram CNN framework. It learns adaptive importance weights of different n-gram features and forms sentence representation by using weighted sum operation on extracted n-gram features, which can largely reduce parameters to be learned and alleviate the threat of over fitting. Experimental results show that the proposed method can improve performances when be used in sentiment and relation classification tasks.

Finger vein image retrieval is one significant technique for performing fast identification especially in large-scale applications. However, most existing retrieval methods were based on fixed-scale feature of non-overlapped rectangular image block, in which the representation ability of feature and the local consistency of vein pattern were both overlooked. And the weak encoding (e.g., predefined threshold based binarization) was also limited the retrieval performance. Focusing on these problems, this paper proposes a novel finger vein image retrieval framework based on similarity-preserving encoding of scale-varied superpixel feature. In the framework, locally consistent pixels in one superpixel are used as a unit of feature representation, and the feature length is varied with the category of the superpixel classified by the variance of lowest dimensional feature. Additionally, the feature compaction and feature rotation based encoding can minimize the quantization loss and preserve the similarity between the scale-varied feature and the encoded binary codes. Experimental results on six public finger vein databases demonstrate that the superiority of the proposed coding scale-varied superpixel feature based retrieval approach over the state-of-the-arts.

Finger vein pattern, as a promising hand-based biometric technology, has been well studied in recent years. In this paper, a new superpixel-based finger vein recognition method is presented. In the proposed method, we develop two types of effective superpixels, i.e. stable superpixel and discriminative superpixel to represent finger vein image and these superpixels are expected to play different roles in matching stage. In detail, the stable and discriminative superpixels are firstly learned from the training images for each enrolled class. When verifying a testing image, we just compare the superpixels at the same location as the two types of superpixels in template. Then, the two types of superpixels are combined utilizing a reversible weight-based fusion method in score level. Additionally, to further improve the recognition performance, we explore the superpixel context feature (SPCF). For each superpixel the SPCF is obtained by comparing the current superpixel with its surrounding neighbors. In the final matching stage, we integrate the matching score of two types of superpixels and it of the SPCF using the weighted SUM fusion method. The experimental results on two open finger vein databases, i.e. PolyU and SDUMLA-FV, show that our method not only performs better than the existing superpixel-based method, but also has advantages in comparison with some traditional ones.

Finger vein pattern has become one of the most promising biometric identifiers. In this paper, a robust method based on Bag-of-Words (BoW) is developed for finger vein verification. Firstly, some robust and discriminative visual words are learned from local base features such as Local Binary Pattern (LBP), Mean Curvature and Webber Local Descriptor (WLD). We name these visual words as Finger Vein Textons (FVTs). Secondly, each image is mapped into a FVTs matrix. Finally, spatial pyramid matching (SPM) method is applied to maintain spatial layout information by representing each image as pyramid histogram which is performed for matching by histogram intersection function. Experimental results show that the proposed method achieves satisfactory performance both on our database and the open PolyU database. In addition, our method also has strong robustness and high accuracy on the self-built rotation and illumination databases.