nils-herrmann/clean_scirepeval huggingface dataset:
Biometric Verification: Looking Beyond Raw Similarity Scores

Most biometric verification techniques make decisions based solely on a score that represents the similarity of the query template with the reference template of the claimed identity stored in the database. When multiple templates are available, a fusion scheme can be designed using the similarities with these templates. Combining several templates to construct a composite template and selecting a set of useful templates has also been reported in addition to usual multi-classifier fusion methods when multiple matchers are available. These commonly adopted techniques rarely make use of the large number of non-matching templates in the database or training set. In this paper, we highlight the usefulness of such a fusion scheme while focusing on the problem of fingerprint verification. For each enrolled template, we identify its cohorts (similar fingerprints) based on a selection criterion. The similarity scores of the query template with the reference template and its cohorts from the database are used to make the final verification decision using two approaches: a likelihood ratio based normalization scheme and a Support Vector Machine (SVM)-based classifier. We demonstrate the accuracy improvements using the proposed method with no a priori knowledge about the database or the matcher under consideration using a publicly available database and matcher. Using our cohort selection procedure and the trained SVM, we show that accuracy can be significantly improved at the expense of few extra matches.
Dynamic behavior analysis in compressed fingerprint videos

Traditional fingerprint acquisition is limited to single-image capture and processing. With the advent of faster capture hardware, faster processors, and advances in video compression standards, newer systems can capture and exploit video signals for tasks that are difficult using a single image. We propose the use of fingerprint video sequences to investigate detecting two aspects of the dynamic behavior of fingerprints. Specifically, we are interested in the detection of distortion of fingerprint impressions due to excessive force and the detection of the positioning of fingers during image capture. These issues often lead to difficulties in establishing a precise match between acquired images. The proposed techniques investigate dynamic characteristics of fingerprints across video sequence frames. A significant advantage of our approach for distortion analysis is that it works directly on MPEG-1,-2 encoded fingerprint video bitstreams. The proposed methods have been tested on the NIST-24 live-scan fingerprint video database and the results are promising. We also describe a new concept called the "resultant biometrics", a new type of biometrics which has both a physiological, physical (e.g., force, torque, linear motion, rotation) component and/or a temporal characteristic, added by a subject to an existing biometric. This resultant biometric is both desirable and efficient in terms of easy modification of compromised biometrics and is harder to produce with spoof body parts.
FPGA-based high performance page layout segmentation

A page layout segmentation algorithm for locating text, background and halftone areas is presented. The algorithm has been implemented on Splash 2-an FPGA-based array processor. The speed as determined by the Xilinx synthesis tools projects an application speed of 5 MHz. For documents of size 1,024/spl times/1,024 pixels, a significant speedup of two orders of magnitude compared to a SparcStation 20 has been achieved.
SLIC: Short-length iris codes

The texture in a human iris has been shown to have good individual distinctiveness and thus is suitable for use in reliable identification. A conventional iris recognition system unwraps the iris image and generates a binary feature vector by quantizing the response of selected filters applied to the rows of this image. Typically there are 360 angular sectors, 64 radial rings, and 2 filter responses. This produces a full-length iris code (FLIC) of about 5760 bytes. In contrast, this paper seeks to shrink the representation by finding those regions of the iris that contain the most descriptive potential. We show through experiments that the regions close to the pupil and sclera contribute least to discrimination, and that there is a high correlation between adjacent radial rings. Using these observations we produce a short-length iris code (SLIC) of only 450 bytes. The SLIC is an order of magnitude smaller the FLIC and yet has comparable performance as shown by results on the MMU2 database. The smaller sized representation has the advantage of being easier to store as a barcode, and also reduces the matching time per pair.
FPGA-based coprocessor for text string extraction

In document understanding, one of the early stages involves extracting text strings from a scanned image of the document. Often, the text is printed on a repetitive background of design patterns for visual effects. For recognition purposes, the text strings need to be extracted eliminating the background. Image morphology based algorithms have been proposed for this purpose. However, image morphology operations are compute intensive. We describe the design and synthesis of a high-performance coprocessor to meet the compute load. The algorithm has been synthesized for Splash 2, an attached processor on Sun hosts. The Xilinx Field-Programmable Gate Array (FPGA) based PEs are programmed using VHDL behavioral modeling. The design can run at near-ASIC speeds of /spl ap/22 MHz clock rate with effective timing of 3 milliseconds per 128/spl times/128 image frame and 3/spl times/3 structuring element. Compared with a SPARC station 20 timings of 1.5 sees, the present implementation has a speed advantage of the order of 500 times.
Generating Registration-free Cancelable Fingerprint Templates

Cancelable biometrics bridges the gap between the convenience of biometric authentication and security offered by cryptographic systems. There have been several prior attempts to construct cancelable templates out of fingerprint biometrics. However, existing approaches require pre-alignment of fingerprint images and therefore, are not robust to image registration errors. In this paper, we propose a provably secure, registration-free construction of cancelable fingerprint templates. Firstly, we present a new fingerprint representation based on localized, self-aligned texture features. Secondly, we demonstrate how to construct cancelable templates from them and also show how to harden the security of the proposed construction further. And finally, we present arguments for it resilience against various modes of adversarial attack.
Parallel implementation of vision algorithms on workstation clusters

Parallel implementations of two computer vision algorithms on distributed cluster platforms are described. The first algorithm is a square-error data clustering method whose parallel implementation is based on the well-known sequential CLUSTER program. The second algorithm is a motion parameter estimation algorithm used to determine correspondence between two images taken of the same scene. Both algorithms have been implemented and tested on cluster platforms using the PVM package. Performance measurements demonstrate that it is possible to attain good performance in terms of execution time and speedup for large-scale problems, provided that adequate memory; swap space, and I/O capacity are available at each node.
FPGA-based computing in computer vision

Algorithms in computer vision are characterized by (i) complex and repetitive operations; (ii) large amount of data and (iii) a variety of data interaction (e.g., point operations, neighborhood operations, global operations). Based on the computation and communication complexity, vision algorithms have been characterized into three categories: (i) low-level, (ii) intermediate-level and (iii) high-level. In this paper, we describe the usage of custom computing approach to meet the computation and communication needs of computer vision algorithms. By customizing hardware architecture for every application at the instruction level, the optimal grain size needed for the problem at hand and the instruction granularity can be matched. Field Programmable Gate Array (FPGA) based processing elements (PEs) are being used to provide this facility. Using programmable communication resources, the diverse communication requirements can be met. A vision system needs to integrate hardware for the three levels. A custom computing approach alleviates the problem of achieving optimal granularity for different stages as the same hardware gets reconfigured at a software level for different levels of the application. We demonstrate the advantages of our approach using Splash 2-a Xilinx 4010-based custom computer.
Physics-based revocable face recognition

We present a face reconstruction approach for revocable face matching. The proposed approach generates photometrically valid cancelable face images by following the image formation process. Given a face image, the approach estimates facial albedo followed by a subject-specific key based photometric deformation to generate a cancelable face image. The proposed approach allows for using any available face matcher to perform verification or recognition in the transformed domain, a capability missing from most existing works on cancelable face matching. Experiments are performed to evaluate the performance, privacy and cancelable aspects of the face images reconstructed using the approach. Results obtained are very promising and make a strong case for such backward compatible cancelable face representations that can seamlessly make use of advancements in automatic face recognition research.
A new approach for iris segmentation

Iris segmentation is an important first step for high accuracy iris recognition. A robust iris segmentation procedure should be able to handle noise, occlusion and non-uniform lighting. It also impacts system accuracy - high FAR or FRR values may come directly from bad or wrong segmentations. In this paper a simple new approach for iris segmentation is proposed that tries to integrate quality evaluation ideas directly into the segmentation algorithm. By cutting out all the bad areas, the fraction of the iris that remains can be used as a comprehensive quality measure. This eliminates images with high occlusion (e.g. by the eyelids) as well as images with other quality problems (e.g. low contrast), all using the same mechanism. The proposed method has been tested on a medium-sized (450 image) public database (MMU1) and the score distribution investigated. We also show that, as expected, overall matching accuracy can be improved by rejecting images which have a low quality assessment, thus validating the utility of this measure.
Secure and Robust Iris Recognition Using Random Projections and Sparse Representations

Noncontact biometrics such as face and iris have additional benefits over contact-based biometrics such as fingerprint and hand geometry. However, three important challenges need to be addressed in a noncontact biometrics-based authentication system: ability to handle unconstrained acquisition, robust and accurate matching, and privacy enhancement without compromising security. In this paper, we propose a unified framework based on random projections and sparse representations, that can simultaneously address all three issues mentioned above in relation to iris biometrics. Our proposed quality measure can handle segmentation errors and a wide variety of possible artifacts during iris acquisition. We demonstrate how the proposed approach can be easily extended to handle alignment variations and recognition from iris videos, resulting in a robust and accurate system. The proposed approach includes enhancements to privacy and security by providing ways to create cancelable iris templates. Results on public data sets show significant benefits of the proposed approach.
Convolution on Splash 2

Convolution is a fundamental operation in many signal and image processing applications. Since the computation and communication pattern in a convolution operation is regular, a number of special architectures have been designed and implemented for this operator. The Von Neumann architectures cannot meet the real-time requirements of applications that use convolution as an intermediate step. We combine the advantages of systolic algorithms with the low cost of developing application specific designs using field programmable gate arrays (FPGAs) to build a scalable convolver for use in computer vision systems. The performance of the systolic algorithm of (Kung et al., 1981) is compared theoretically and experimentally with many other convolution algorithms reported in the literature. The implementation of a convolution operation on Splash 2, an attached processor based on Xilinx 4010 FPGAs, is reported with impressive performance gains.
Exploring Ridge Curvature for Fingerprint Indexing

One of the main challenges in building an efficient and scalable automatic fingerprint identification system is to identify features which are highly discriminative and are reproducible across different prints of the same finger. Most existing fingerprint matching approaches rely on minutiae geometry. Relatively, little effort has gone into analyzing ridge flow patterns present in the fingerprint, partly due to difficulty in extracting robust discriminative features from the fingerprint images. In this paper, we analyze the usefulness of ridge curvature information for fingerprint matching and classification applications. Specifically, for an indexing framework, we explore whether the curvature information can be utilized along with the existing minutiae geometry-based features for further reducing the number of potential candidates for fingerprint identification. Experimental results indicate the robustness of the proposed curvature-based characterization and its usefulness in improving the efficiency of existing fingerprint-based identification systems.
Clustering using a coarse-grained parallel genetic algorithm: a preliminary study

Genetic algorithms (GA) are useful in solving complex optimization problems. By posing pattern clustering as an optimization problem, GAs can be used to obtain optimal minimum squared error partitions. In order to improve the total execution time, a distributed algorithm has been developed using the divide and conquer approach. Using a standard communication library called PVM, the distributed algorithm has been implemented on a workstation cluster: the GA approach gives better quality clusters for many data sets compared to a standard K-means clustering algorithm. We have achieved a near linear speedup for the distributed implementation.
Face recognition using early biologically inspired features

Biologically inspired model (BIM) is proven to be an effective feature representation approach for visual object categorization. In BIM, two successive S(simple)-to-C(complex) hierarchical layers are performed to simulate the visual perception process of primate visual cortex. However, the intensive computational cost above C1 layer in BIM extremely limits its application in real-time object recognition tasks. This paper proposes to use a set of improved early biologically inspired features (EBIF, including S1 and C1) for face recognition, in which pyramidal statistics of mean and standard deviation rather than MAX pooling are used for scale-tolerant feature condensation and local normalization is performed on C1 layer. Incremental PCA (Principal Component Analysis) and LDA (Linear Discriminant Analysis) are then combined to efficiently learn a discriminant subspace for feature dimensionality reduction. In the matching stage, Cosine similarity is adopted as the distance metric for a given face pair. Experimental results on two public face datasets and a mobile face dataset show the effectiveness of the proposed method.
Image mosaicing for rolled fingerprint construction

With the use of inkless scanners as input devices for acquiring fingerprints of a person, the digital image of the finger is restricted to the area in contact with the sensor The conventional method of fingerprint image acquisition involves obtaining a nail-to-nail image of the finger known as the rolled fingerprint impression. We present a method of constructing a rolled fingerprint from an image sequence of partial fingerprints using a live-scan fingerprint imager.
The relation between the ROC curve and the CMC

The cumulative match curve (CMC) is used as a measure of 1: m identification system performance. It judges the ranking capabilities of an identification system. The receiver operating characteristic curve (ROC curve) of a verification system, on the other hand, expresses the quality of a 1:1 matcher. The ROC plots the false accept rate (FAR) of a 1:1 matcher versus the false reject rate (FRR) of the matcher. We show that the CMC is also related to the FAR and FRR of a 1:1 matcher, i.e., the matcher that is used to rank the candidates by sorting the scores. This has as a consequence that when a 1:1 matcher is used for identification, that is, for sorting match scores from high to low, the CMC does not offer any additional information beyond the FAR and FRR curves. The CMC is just another way of displaying the data and can be computed from the FAR and FRR.
Computer Vision Algorithms on Reconfigurable Logic Arrays

Computer vision algorithms are natural candidates for high performance computing systems. Algorithms in computer vision are characterized by complex and repetitive operations on large amounts of data involving a variety of data interactions (e.g., point operations, neighborhood operations, global operations). In this paper, we describe the use of the custom computing approach to meet the computation and communication needs of computer vision algorithms. By customizing hardware architecture at the instruction level for every application, the optimal grain size needed for the problem at hand and the instruction granularity can be matched. A custom computing approach can also reuse the same hardware by reconfiguring at the software level for different levels of the computer vision application. We demonstrate the advantages of our approach using Splash 2-a Xilinx 4010-based custom computer.
Improving Cross-Resolution Face Matching Using Ensemble-Based Co-Transfer Learning

Face recognition algorithms are generally trained for matching high-resolution images and they perform well for similar resolution test data. However, the performance of such systems degrades when a low-resolution face image captured in unconstrained settings, such as videos from cameras in a surveillance scenario, are matched with high-resolution gallery images. The primary challenge, here, is to extract discriminating features from limited biometric content in low-resolution images and match it to information rich high-resolution face images. The problem of cross-resolution face matching is further alleviated when there is limited labeled positive data for training face recognition algorithms. In this paper, the problem of cross-resolution face matching is addressed where low-resolution images are matched with high-resolution gallery.A co-transfer learning framework is proposed, which is a cross-pollination of transfer learning and co-training paradigms and is applied for cross-resolution face matching. The transfer learning component transfers the knowledge that is learnt while matching high-resolution face images during training to match low-resolution probe images with high-resolution gallery during testing. On the other hand, co-training component facilitates this transfer of knowledge by assigning pseudolabels to unlabeled probe instances in the target domain. Amalgamation of these two paradigms in the proposed ensemble framework enhances the performance of cross-resolution face recognition. Experiments on multiple face databases show the efficacy of the proposed algorithm and compare with some existing algorithms and a commercial system. In addition, several high profile real-world cases have been used to demonstrate the usefulness of the proposed approach in addressing the tough challenges.
An FPGA-based point pattern matching processor with application to fingerprint matching

We describe the design and synthesis of a high-performance coprocessor for point pattern matching with application to fingerprint matching using Splash 2-an attached processor for SUN SPARCstation hosts. Each of the field programmable gate array (FPGA)-based processing elements (PEs) is programmed using VHDL behavioral modeling. Using the simulation tools, the program logic is verified. The final control bit stream for the PEs is generated using the synthesis tools. The point feature matching coprocessor can run at a peak speed of 17.1 MHz per feature vector of a fingerprint. With 65 features per fingerprint, the matching speed has been projected at the rate of 2.6*10/sup 5/ fingerprints/sec. The synthesized coprocessor was tested on a 10000 fingerprint database.
Fake iris detection using structured light

Iris recognition has gained popularity due to factors such as its perceived high accuracy, significant usability advantages attributed to its non-contact acquisition method, and the availability of low cost sensors due to improvements in technology. However, non-contact biometrics authentication systems are vulnerable to different types of attacks than contact-type biometrics, such as fingerprints, for which there are a number of simple techniques to guard against attacks. In particular, the fashion industry has developed designer contact lenses with patterns that range from a simple change in eye color to the imposition of stars or other festive decorations. As these lenses are readily available and can be personalized at a very affordable price, their use in thwarting or spoofing iris-based authentication systems becomes plausible. Given the high security nature of many of these systems, there is a urgent need for a some countermeasure to this type of attack. In this paper, we describe a novel method to detect the presence of fake iris patterns, such as designer contact lenses, during the image acquisition stage to further enhance the basic security value of iris biometrics. Exploiting the anatomy and geometry of the human eye, we present a structured light projection method to detect the presence of artificial items obscuring the real iris. The detection principle has been verified using an inexpensive experimental setup consisting of a miniature projector and an offset camera. We also describe a novel algorithm to process the acquired images to find patterned contact lenses, and measure its performance using data collected with our apparatus. We argue that the addition of the proposed system and algorithm to existing iris biometrics based authentication systems will significantly improve their security.
Novel Approaches for Minutiae Verification in Fingerprint Images

A majority of the existing fingerprint recognition algorithms are based on matching minutia features. Therefore, minutiae extraction is one of the critical steps in fingerprint verification algorithms. Poor quality fingerprint images lead to missing and spurious minutiae that degrade the performance of the matching system. We propose two new techniques for minutiae verification based on non-trivial gray level features. The proposed features intuitively represent the structural properties of the minutiae neighborhood leading to better classification. We use directionally selective steerable wedge filters to differentiate between minutiae and non-minutiae neighborhoods. We also propose a second technique based on Gabor expansion that results in even better discrimination. We present an objective evaluation of both the algorithms.