nils-herrmann/clean_scirepeval huggingface dataset:
Reconstruction-based supervised hashing

In this paper, we propose a reconstruction-based supervised hashing (RSH) method to learn compact binary codes with holistic structure preservation for large scale image search. Unlike most existing hashing methods which consider pair-wise similarity, our method exploits the structural information of samples by employing a reconstruction-based criterion. Moreover, the label information of samples is also utilized to enhance the discriminative power of the teamed hash codes. Specifically, our method minimizes the distance between each point and the selected generated-structure with the same class label and maximizes the distance between each point and the selected generated-structure with different class labels. Experimental results on two widely used image datasets demonstrate the effectiveness of the proposed method.
Detecting Altered Fingerprints

The widespread deployment of Automated Fingerprint Identification Systems (AFIS) in law enforcement and border control applications has prompted some individuals with criminal background to evade identification by purposely altering their fingerprints. Available fingerprint quality assessment software cannot detect most of the altered fingerprints since the implicit image quality does not always degrade due to alteration. In this paper, we classify the alterations observed in an operational database into three categories and propose an algorithm to detect altered fingerprints. Experiments were conducted on both real-world altered fingerprints and synthetically generated altered fingerprints. At a false alarm rate of 7%, the proposed algorithm detected 92% of the altered fingerprints, while a well-known fingerprint quality software, NFIQ, only detected 20% of the altered fingerprints.
Fingerprint Reconstruction: From Minutiae to Phase

Fingerprint matching systems generally use four types of representation schemes: grayscale image, phase image, skeleton image, and minutiae, among which minutiae-based representation is the most widely adopted one. The compactness of minutiae representation has created an impression that the minutiae template does not contain sufficient information to allow the reconstruction of the original grayscale fingerprint image. This belief has now been shown to be false; several algorithms have been proposed that can reconstruct fingerprint images from minutiae templates. These techniques try to either reconstruct the skeleton image, which is then converted into the grayscale image, or reconstruct the grayscale image directly from the minutiae template. However, they have a common drawback: Many spurious minutiae not included in the original minutiae template are generated in the reconstructed image. Moreover, some of these reconstruction techniques can only generate a partial fingerprint. In this paper, a novel fingerprint reconstruction algorithm is proposed to reconstruct the phase image, which is then converted into the grayscale image. The proposed reconstruction algorithm not only gives the whole fingerprint, but the reconstructed fingerprint contains very few spurious minutiae. Specifically, a fingerprint image is represented as a phase image which consists of the continuous phase and the spiral phase (which corresponds to minutiae). An algorithm is proposed to reconstruct the continuous phase from minutiae. The proposed reconstruction algorithm has been evaluated with respect to the success rates of type-I attack (match the reconstructed fingerprint against the original fingerprint) and type-II attack (match the reconstructed fingerprint against different impressions of the original fingerprint) using a commercial fingerprint recognition system. Given the reconstructed image from our algorithm, we show that both types of attacks can be successfully launched against a fingerprint recognition system.
Learning Deep Binary Descriptor with Multi-quantization

In this paper, we propose an unsupervised feature learning method called deep binary descriptor with multi-quantization (DBD-MQ) for visual matching. Existing learning-based binary descriptors such as compact binary face descriptor (CBFD) and DeepBit utilize the rigid sign function for binarization despite of data distributions, thereby suffering from severe quantization loss. In order to address the limitation, our DBD-MQ considers the binarization as a multi-quantization task. Specifically, we apply a K-AutoEncoders (KAEs) network to jointly learn the parameters and the binarization functions under a deep learning framework, so that discriminative binary descriptors can be obtained with a fine-grained multi-quantization. Extensive experimental results on different visual analysis including patch retrieval, image matching and image retrieval show that our DBD-MQ outperforms most existing binary feature descriptors.
Fingerprint Representation and Matching in Ridge Coordinate System

Fingerprints are generally represented and analyzed in Cartesian or polar coordinates. In this paper, however, fingerprints are represented and analyzed in a novel coordinate system, called ridge coordinate system (RCS), which is based on a ridge and an oriented point on the ridge. Using RCSs based on lots of ridges, we obtain a robust representation scheme of the ridge (skeleton) image of a fingerprint. Based on this representation, an alignment-based fingerprint matching algorithm is proposed. Experimental results on FVC2002 demonstrate the validity of the proposed algorithm
Localized multi-kernel discriminative canonical correlation analysis for video-based person re-identification

This paper presents a localized multi-kernel discriminative canonical correlation analysis (LMKDCCA) approach for video-based person re-identification, which aims to match persons from pedestrian videos captured by non-overlapping cameras. Unlike conventional methods, our approach models each pedestrian video as a point on the Riemannian manifold and learns similarity over these points under the multiple kernel learning framework. For each given person video, we first represent it as a symmetric positive definite (SPD) matrix which lies on a Riemannian manifold and compute the similarity of multiple SPDs. Then, we develop an LMKDCCA algorithm to learn a nonlinear distance metric which effectively combines these SPDs to exploit complementary information for similarity measure. Experimental results on the iLIDS-VID and PRID 2011 datasets show that our approach achieves the state-of-the-arts.
Registration of coronary arteries in computed tomography angiography images using Hidden Markov Model

Computed tomography angiography (CTA) allows for not only diagnosis of coronary artery disease (CAD) with high spatial resolution but also monitoring the remodeling of vessel walls in the progression of CAD. Alignment of coronary arteries in CTA images acquired at different times (with a 3-7 years interval) is required to visualize and analyze the geometric and structural changes quantitatively. Previous work in image registration primarily focused on large anatomical structures and leads to suboptimal results when applying to registration of coronary arteries. In this paper, we develop a novel method to directly align the straightened coronary arteries in the cylindrical coordinate system guided by the extracted centerlines. By using a Hidden Markov Model (HMM), image intensity information from CTA and geometric information of extracted coronary arteries are combined to align coronary arteries. After registration, the pathological features in two straightened coronary arteries can be directly visualized side by side by synchronizing the corresponding cross-sectional slices and circumferential rotation angles. By evaluating with manually labeled landmarks, the average distance error is 1.6 mm.
Nonlinear Sparse Hashing

To facilitate fast similarity search, this paper proposes to encode the nonlinear similarity and image structure as compact binary codes. Rather than adopting single matrix as projection in the literature, we employ a nonlinear transformation in the form of multilayer neural network to generate binary codes to capture the local structure between data samples. Specifically, we train the network such that the quantization loss is minimized and the variance over all bits is maximized. In addition, we capture the salient structure of image samples at the abstract level with sparsity constraint and inherit the generalization power to unseen samples. Furthermore, we incorporate the supervisory label information into the learning procedure to take advantage of the manual label. To obtain the desired binary codes and the parameterized nonlinear transformation, we optimize the formulated objective problem over each variable with an iterative alternating method. To validate the efficacy of the proposed hashing approach, we conduct experiments on three widely used datasets, namely CIFAR10, MNIST, and SUN397, by comparing with several recent proposed hashing methods.
Altered Fingerprints: Analysis and Detection

The widespread deployment of Automated Fingerprint Identification Systems (AFIS) in law enforcement and border control applications has heightened the need for ensuring that these systems are not compromised. While several issues related to fingerprint system security have been investigated, including the use of fake fingerprints for masquerading identity, the problem of fingerprint alteration or obfuscation has received very little attention. Fingerprint obfuscation refers to the deliberate alteration of the fingerprint pattern by an individual for the purpose of masking his identity. Several cases of fingerprint obfuscation have been reported in the press. Fingerprint image quality assessment software (e.g., NFIQ) cannot always detect altered fingerprints since the implicit image quality due to alteration may not change significantly. The main contributions of this paper are: 1) compiling case studies of incidents where individuals were found to have altered their fingerprints for circumventing AFIS, 2) investigating the impact of fingerprint alteration on the accuracy of a commercial fingerprint matcher, 3) classifying the alterations into three major categories and suggesting possible countermeasures, 4) developing a technique to automatically detect altered fingerprints based on analyzing orientation field and minutiae distribution, and 5) evaluating the proposed technique and the NFIQ algorithm on a large database of altered fingerprints provided by a law enforcement agency. Experimental results show the feasibility of the proposed approach in detecting altered fingerprints and highlight the need to further pursue this problem.
Learning Deep Sharable and Structural Detectors for Face Alignment

Face alignment aims at localizing multiple facial landmarks for a given facial image, which usually suffers from large variances of diverse facial expressions, aspect ratios and partial occlusions, especially when face images were captured in wild conditions. Conventional face alignment methods extract local features and then directly concatenate these features for global shape regression. Unlike these methods which cannot explicitly model the correlation of neighbouring landmarks and motivated by the fact that individual landmarks are usually correlated, we propose a deep sharable and structural detectors (DSSD) method for face alignment. To achieve this, we firstly develop a structural feature learning method to explicitly exploit the correlation of neighbouring landmarks, which learns to cover semantic information to disambiguate the neighbouring landmarks. Moreover, our model selectively learns a subset of sharable latent tasks across neighbouring landmarks under the paradigm of the multi-task learning framework, so that the redundancy information of the overlapped patches can be efficiently removed. To better improve the performance, we extend our DSSD to a recurrent DSSD (R-DSSD) architecture by integrating with the complementary information from multi-scale perspectives. Experimental results on the widely used benchmark datasets show that our methods achieve very competitive performance compared to the state-of-the-arts.
Deep Localized Metric Learning

Metric learning has been widely used in many visual analysis applications, which learns new distance metrics to measure the similarities of samples effectively. Conventional metric learning methods learn a single linear Mahalanobis metric, yet such linear projections are not powerful enough to capture the nonlinear relationships. Recently, deep metric learning approaches, such as discriminative deep metric learning and deep transfer metric learning, have been introduced to fully exploit the nonlinearity of samples by learning hierarchical nonlinear transformations. However, these methods only learn holistic metrics over the input space and are limited for the heterogeneous data sets, where data varies locally. In this paper, we propose a deep localized metric learning approach for visual recognition by learning multiple fine-grained deep localized metrics. We first learn  $K$  local subspaces and one holistic subspace with the K-auto-encoders-based clustering. Then, given an input pair, we compute its localized distance on each learned subspace and obtain the final distance representation. Finally, we train the entire neural networks to ensure the distances of positive pairs smaller than negative pairs by a large margin. Experimental results on three visual recognition applications, including face recognition, person re-identification, and scene recognition, show that our DLML outperforms most existing metric learning approaches.
2-D Phase Demodulation for Deformable Fingerprint Registration

Fingerprint matching with elastic distortion is very challenging to deal with, and severe fingerprint distortion usually leads to false non-matches. This paper proposes a phase-based registration algorithm which can effectively eliminate the distortion between fingerprints and therefore is beneficial to the subsequent fingerprint matching. The key of the proposed algorithm is to reconstruct the distortion field through unwrapping phase difference between two fingerprints. Experiments on FVC2004, Tsinghua distorted fingerprint database, and NIST SD27 demonstrate that our algorithm outperforms other fingerprint registration methods and significantly improves matching accuracy.
Topology Preserving Structural Matching for Automatic Partial Face Recognition

In this paper, we propose a topology preserving graph matching (TPGM) method for partial face recognition. Most existing face recognition methods extract features from holistic facial images. However, faces in real-world unconstrained environments may be occluded by objects or other faces, which cannot provide the whole face images for description. Keypoint-based partial face recognition methods such as multi-keypoint descriptor with Gabor ternary pattern and robust point set matching match the local keypoints for partial face recognition. However, they simply measure the nodewise similarity without higher order geometric graph information, which are susceptible to noises. To address this, our TPGM method estimates a non-rigid transformation encoding the second-order geometric structure of the graph, so that more accurate and robust correspondence can be computed with the topological information. In order to exploit higher order topological information, we propose a topology preserving structural matching method to construct a higher order structure for each face and estimate the transformation. Experimental results on four widely used face data sets demonstrate that our method outperforms most existing state-of-the-art face recognition methods.
Label-Sensitive Deep Metric Learning for Facial Age Estimation

In this paper, we present a label-sensitive deep metric learning (LSDML) approach for facial age estimation. Motivated by the fact that human age labels are chronologically correlated, our proposed LSDML aims to seek a series of hierarchical nonlinear transformations by deep residual network to project face samples to a latent common space, where the similarity of face pairs is equivalently isotonic to the age difference in a ranking-preserving manner. Since traversal access to total negative samples catastrophically costs and leads to suboptimal, our model learns to mine hard meaningful samples in parallel to learning feature similarity, so that the local manifold of face samples is preserved in the transformed subspace. To better improve the performance on the data set that contains few labeled samples, we further extend our LSDML to a multi-source LSDML method, which aims at maximizing the cross-population correlation of different face aging data sets. Extensive experimental results on four benchmarking data sets show the effectiveness of our proposed approach.
Latent Fingerprint Matching: Fusion of Manually Marked and Derived Minutiae

Matching unknown latent fingerprints lifted from crime scenes to full (rolled or plain) fingerprints in law enforcement databases is of critical importance for combating crime and fighting terrorism. Compared to good quality full fingerprints acquired using live-scan or inking methods during enrollment, latent fingerprints are often smudgy and blurred, capture only a small finger area, and have large nonlinear distortion. For this reason, features (minutiae and singular points) in latents are typically manually marked by trained latent examiners. However, this introduces an undesired interoperability problem between latent examiners and automatic fingerprint identification systems (AFIS); the features marked by examiners are not always compatible with those automatically extracted by AFIS, resulting in reduced matching accuracy. While the use of automatically extracted minutiae from latents can avoid interoperability problem, such minutiae tend to be very unreliable, because of the poor quality of latents. In this paper, we improve latent to full fingerprint matching accuracy by combining manually marked (ground truth) minutiae with automatically extracted minutiae. Experimental results on a public domain database, NIST SD27, demonstrate the effectiveness of the proposed algorithm.
Filtering large fingerprint database for latent matching

Latent fingerprint identification is of critical importance to law enforcement agencies in apprehending criminals. Considering the huge size of fingerprint databases maintained by law enforcement agencies, exhaustive one-to-one matching is impractical and a database filtering technique is necessary to reduce the search space. Due to low image quality and small finger area of latent fingerprints, it is necessary to use several features for an efficient and reliable filtering system. A multi-stage filtering system is proposed, which utilizes pattern type, singular points and orientation field. We have tested our system by searching 258 latent fingerprints in NIST SD27 against a background database containing 10,258 rolled fingerprints (obtained by combining 2,000 in NIST SD4, 8,000 in SD14 and 258 in SD27). Although latent fingerprints contain very limited information, the filtering system not only improved the matching speed by three fold but also improved the rank-1 matching accuracy from 70.9% to 73.3%.
Smooth Representation Clustering

Subspace clustering is a powerful technology for clustering data according to the underlying subspaces. Representation based methods are the most popular subspace clustering approach in recent years. In this paper, we analyze the grouping effect of representation based methods in depth. In particular, we introduce the enforced grouping effect conditions, which greatly facilitate the analysis of grouping effect. We further find that grouping effect is important for subspace clustering, which should be explicitly enforced in the data self-representation model, rather than implicitly implied by the model as in some prior work. Based on our analysis, we propose the SMooth Representation (SMR) model. We also propose a new affinity measure based on the grouping effect, which proves to be much more effective than the commonly used one. As a result, our SMR significantly outperforms the state-of-the-art ones on benchmark datasets.
OSRI: A Rotationally Invariant Binary Descriptor

Binary descriptors are becoming widely used in computer vision field because of their high matching efficiency and low memory requirements. Since conventional approaches, which first compute a floating-point descriptor then binarize it, are computationally expensive, some recent efforts have focused on directly computing binary descriptors from local image patches. Although these binary descriptors enable a significant speedup in processing time, their performances usually drop a lot due to orientation estimation errors and limited description abilities. To address these issues, we propose a novel binary descriptor based on the ordinal and spatial information of regional invariants (OSRIs) over a rotation invariant sampling pattern. Our main contributions are twofold: 1) each bit in OSRI is computed based on difference tests of regional invariants over pairwise sampling-regions instead of difference tests of pixel intensities commonly used in existing binary descriptors, which can significantly enhance the discriminative ability and 2) rotation and illumination changes are handled well by ordering pixels according to their intensities and gradient orientations, meanwhile, which is also more reliable than those methods that resort to a reference orientation for rotation invariance. Besides, a statistical analysis of discriminative abilities of different parts in the descriptor is conducted to design a cascade filter which can reject nonmatching descriptors at early stages by comparing just a small portion of the whole descriptor, further reducing the matching time. Extensive experiments on four challenging data sets (Oxford, 53 Objects, ZuBuD, and Kentucky) show that OSRI significantly outperforms two state-of-the-art binary descriptors (FREAK and ORB). The matching performance of OSRI with only 512 bits is also better than the well-known floating-point descriptor SIFT (4K bits) and is comparable with the state-of-the-art floating-point descriptor MROGH (6K bits), while it is two orders of magnitude faster to match than SIFT and MROGH.
A video surveillance system for fingerprint acquisition

In fingerprint-based watch-list systems used by law enforcement, immigration, and military agencies, the targeted users (such as criminals, illegal immigrants, terrorists) have strong incentive to cheat the fingerprint system. A simple but effective method to cheat the system is to present the wrong fingers or even not a finger (e.g., palm). The current solution to prevent such behavior is to let the official closely monitor the fingerprint acquisition process. However, automatic solution is desired because the number and scale of fingerprint-based watch-list systems are rapidly increasing while human labor is expensive. We propose a video surveillance system to ensure the validity of input fingers. The proposed system captures the region around the fingerprint scanner using a webcam, determines whether the posture of the hand is valid, and estimates finger position (left index, right middle). Experimental results demonstrate the validity of the proposed algorithm.