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Biometric System
                    Template Editing
                Template Replacement




Template Editing & Replacem...
Biometric System
                    Template Editing
                Template Replacement




Biometric System
   Overvie...
Biometric System
                         Template Editing
                     Template Replacement


Overture
   20 Janu...
Biometric System    Overview
                        Template Editing    Template Representativeness
                    T...
Biometric System    Overview
                        Template Editing    Template Representativeness
                    T...
Biometric System    Overview
                           Template Editing    Template Representativeness
                  ...
Biometric System    Overview
                       Template Editing    Template Representativeness
                   Tem...
Biometric System    Clustering Algorithms
                        Template Editing    Editing Algorithms
                 ...
Biometric System    Clustering Algorithms
                         Template Editing    Editing Algorithms
                ...
Biometric System    Clustering Algorithms
                          Template Editing    Editing Algorithms
               ...
Biometric System    Clustering Algorithms
                         Template Editing    Editing Algorithms
                ...
Biometric System    Clustering Algorithms
                          Template Editing    Editing Algorithms
               ...
Biometric System    Clustering Algorithms
                            Template Editing    Editing Algorithms
             ...
Biometric System    Clustering Algorithms
                        Template Editing    Editing Algorithms
                 ...
Biometric System    Clustering Algorithms
                            Template Editing    Editing Algorithms
             ...
Biometric System    Clustering Algorithms
                         Template Editing    Editing Algorithms
                ...
Biometric System    Clustering Algorithms
                        Template Editing    Editing Algorithms
                 ...
Biometric System    Semi-Supervised Template Update
                       Template Editing    Template Update with Replac...
Biometric System    Semi-Supervised Template Update
                        Template Editing    Template Update with Repla...
Biometric System    Semi-Supervised Template Update
                         Template Editing    Template Update with Repl...
Biometric System    Semi-Supervised Template Update
                      Template Editing    Template Update with Replace...
Biometric System    Semi-Supervised Template Update
                         Template Editing    Template Update with Repl...
Biometric System    Semi-Supervised Template Update
                   Template Editing    Template Update with Replacemen...
Biometric System    Semi-Supervised Template Update
                           Template Editing    Template Update with Re...
Biometric System    Semi-Supervised Template Update
                       Template Editing    Template Update with Replac...
Biometric System    Semi-Supervised Template Update
                        Template Editing    Template Update with Repla...
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Freni - Ph.D. Defense Slides

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  1. 1. Biometric System Template Editing Template Replacement Template Editing & Replacement: novel methods for Biometric Template Selection & Update Biagio Freni Advisor: Prof. Fabio Roli Pattern Recognition and Application Group Dept. Electrical Electronic Engineering - University of Cagliari 05 March 2010 Biagio Freni Template Editing & Replacement in Biometric
  2. 2. Biometric System Template Editing Template Replacement Biometric System Overview Template Representativeness State-of-the-Art: Template Selection & Update Template Editing Clustering Algorithms Editing Algorithms Experimental Comparison Template Replacement Semi-Supervised Template Update Template Update with Replacement Results Biagio Freni Template Editing & Replacement in Biometric
  3. 3. Biometric System Template Editing Template Replacement Overture 20 January 2010 . . . A man has been founded dead in a Dubai’s hotel. . . . couple of days later . . . Local Police discovered that 11 main suspects got into the country illegally using forged passports of European citizen. Police found out that pictures in the documents were different from legitimate owner’s pictures. . . . 14 January 2010 just a week before the Dubai affair, EU delegates approved — 594 vs 51, while 37 abstained — the launch of Biometric Passport including owner’s fingerprint and face. Biagio Freni Template Editing & Replacement in Biometric
  4. 4. Biometric System Overview Template Editing Template Representativeness Template Replacement State-of-the-Art: Template Selection & Update What’s Biometric? Biometric refers to the use of physiological or behavioural characteristics, “unique” for each person, with the aim of established people’s identity. Core of Biometric System is represented by Templates. Biagio Freni Template Editing & Replacement in Biometric
  5. 5. Biometric System Overview Template Editing Template Representativeness Template Replacement State-of-the-Art: Template Selection & Update Template Selection & Update The issue of template selection and update, in biometric recognition systems, is twofold and is related to: Selection during Enrollment regarding the effective creation of representative template gallery of client populations, keeping the number of templates as small as possible at the same time. Update during Authentication regarding the need of adapt over time templates, in order to capture the variations, in the biometric traits not presented in the time of enrollment. Selection & Update are different problems that share the common notion of “best representative” templates. Biagio Freni Template Editing & Replacement in Biometric
  6. 6. Biometric System Overview Template Editing Template Representativeness Template Replacement State-of-the-Art: Template Selection & Update State-of-the-Art: summary State-of-the-Art can be summurized by following modalities 1 : Supervised: requires human intervention to labeling data. Semi-Supervised 2 : queries labelled by the system are used for the task. Offline: a bunch of semi-labelled data are stored during the system authentication, later, they are used to update system’s templates when the system itself is not operative. Online: each coming query is evaluated by the system during authentication phase, template adaptation is performed online. 1 A. Rattani, B. Freni, G.L. Marcialis, F. Roli, Template Update Methods in Adaptive Biometric Systems: A Critical Review, ICB09, pp 847-856. 2 B. Freni, G.L. Marcialis, and F. Roli, Online and offline fingerprint template update using minutiae: an experimental comparison, AMDO08, July, 9-11, 2008, Eds., Springer LNCS 5098, pp. 441-448. Biagio Freni Template Editing & Replacement in Biometric
  7. 7. Biometric System Overview Template Editing Template Representativeness Template Replacement State-of-the-Art: Template Selection & Update PhD work This PhD work explored the whole S-o-A and new methods have been proposed and published: S-o-A: Template Update Methods in Adaptive Biometric Systems: A Critical Review, al. et Freni, ICB09. Supervised: Template Selection by Editing Algorithms: a case of Study in Face Recognition, Freni et al., S+SSPR08. Semi-Supervised Offline: Online and offline fingerprint template update using minutiae: an experimental comparison, Freni et al., AMDO08. Online: Replacement algorithms for fingerprint template update, Freni et al., ICIAR08. For sake of time just two works are addressed in this talk Editing methods for Template Selection and Replacement algorithms for Template Update. Biagio Freni Template Editing & Replacement in Biometric
  8. 8. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison Template selection in Biometric Problem statement Given a set of N templates for a given person, select K templates that “best” represent the owner’s identity. State-of-the-Art Derived from the clustering theory, consisting in exploring each template gallery according with two criteria: maximum similarity among templates (MDIST), maximum variation among them (DEND). Main Cons 1. The procedure is not fully automatic since it requires the manual insertion of parameter K . 2. All the template gallery are resized to the same dimension K , without taking into account “intrinsic” difficulty of each client. Biagio Freni Template Editing & Replacement in Biometric
  9. 9. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison SoA MDIST: maximum similarity among templates apply to all client’s gallery 1. Compute distance between N templates 2. For each template compute the average distance with the other (N − 1) 3. Choose K templates with smallest average distance as new selected gallery Biagio Freni Template Editing & Replacement in Biometric
  10. 10. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison SoA DEND: maximum variation among templates apply to all client’s gallery 1. Generate a NxN dissimilarity matrix DM 2. Apply Complete Link Clustering to DM in order to generate a Dendrogram D, using D to identify K clusters 3. For each K cluster select the center 4. The set of templates selected in 3. represent a new selected gallery Biagio Freni Template Editing & Replacement in Biometric
  11. 11. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison Novel Proposal: Template Editing for Biometric Editing Algorithms Editing algorithms belong to the K − NN classifier theory. K − NN use a set of prototype to perfom classification. A pattern is classified according to the majority of “K ” prototypes close to it. Biometric could be seen as a “1 − NN” classifier where templates are prototypes. Editing consist in generating from a given Template Set T a subset E able to maintain the same classification accuracy on T itself. Characteristics of Editing Algorithms: 1. the procedure is completly automatic 2. build up variable length galleries accordingly with the “difficult” of each client 3. a superior generalization ability is expected Biagio Freni Template Editing & Replacement in Biometric
  12. 12. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison 3 CNN: Condensed Nearest Neighbour 1. E ← x1, ..., xC , C number of clients, T template set, E edited set and x1..xC are templates randomly selected from T 2. T ← T − E 3. classify T using E 4. Y set of misclassified templates in T 5. if Y = φ then 5.1 E ← E ∪ Y 5.2 T ← T − Y 5.3 repeat from point 4 6. Stop 3 P.E. Hart, The Condensed Nearest Neighbor Rule, IEEE Transactions on Information Theory, 14, 515-516. Biagio Freni Template Editing & Replacement in Biometric
  13. 13. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison 4 RNN: Reduced Nearest Neighbour 1. E ← T 2. for each x ∈ E 2.1 E ←E −x 2.2 classify T using E 2.3 Y set of misclassified templates in T 2.4 if Y = φ then 2.4.1 E ← E ∪ x 3. Stop 4 G.W. Gates, The Reduced Nearest Neighbor Rule, IEEE Transactions on Information Theory, 18 (3) 431-433. Biagio Freni Template Editing & Replacement in Biometric
  14. 14. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison Data sets, Protocol and Perfomance Data sets Results are carried out over Equinox, public Faces Dataset. 50 clients have been randomly choosen from the dataset. Each one made up of 100 samples. A total of 5000 faces images. Protocol All the images have been grouped in two equal size sets, T and t. T has been used as Template Set and t as a complete separated test set to assess performance. Performance System’s performance has been evaluated as identification accuracy : number of correct identified queries over total number of submitted queries. Results are showed as mean and (std) over six runs. Biagio Freni Template Editing & Replacement in Biometric
  15. 15. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison 5 Results: Accuracy Accuracy over a test set obtained by different selection methods. Gallery #instances×class TEST TRAIN 50 (0) 99.62 (0.14) CNN 7 (3) 97.6 (0.45) SNN 4 (3) 73.66 (3.31) RNN 17 (9) 98.43 (0.53) ENN 49 (1) 99.35 (0.27) MDIST 6 (0) 94.15 (0.68) MDIST 9 (0) 96.56 (0.58) DEND 6 (0) 89.11 (1.39) DEND 9 (0) 94.03 (0.70) 5 B. Freni, G.L. Marcialis, and F. Roli, Template Selection by Editing Algorithms: a case of Study in Face Recognition, S+SSPR08, Springer LNCS5342, 755-764. Biagio Freni Template Editing & Replacement in Biometric
  16. 16. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison Results: Client’s Accuracy Difficult clients Gallery #classes #instances TEST MDIST 9 DEND 9 CNN 8 12 96.18 93.78 87.56 RNN 41 20 98.58 96.05 93.25 ENN 50 49 99.35 96.56 94.03 Easy clients Gallery #classes #instances TEST MDIST 6 DEND 6 CNN 21 4 98.04 96.89 93.67 SNN 31 3 60.70 94.33 90.89 RNN 4 3 98.08 98.96 95.76 Biagio Freni Template Editing & Replacement in Biometric
  17. 17. Biometric System Clustering Algorithms Template Editing Editing Algorithms Template Replacement Experimental Comparison Summary Editing algorithms have been showed as a good alternative to the State-of-the-Art Template Selection techniques. Results pointed out main characteristics of Editing algorithms: 1. Completly automatic procedures, no futher intervention is needed by supervisor. 2. Capability to build up variable length galleries, according to client intrinsic difficulty. 3. Superior identification accuracy. As a step futher a combined use of both techniques could be investigated. Biagio Freni Template Editing & Replacement in Biometric
  18. 18. Biometric System Semi-Supervised Template Update Template Editing Template Update with Replacement Template Replacement Results Template Update in Biometric Problem statement The problem is quite intuitive and consists in making adaptive the biometric recognition systems over the time. Templates collected during enrollment tend to be non representative by the time, due by the large intra-class variation. Performing several enrollment sessions is expensive. State-of-the-Art Semi-supervised paradigms exploit unlabelled samples submitted to the system in order to find out “highly genuine” to adapt system’s templates. Biagio Freni Template Editing & Replacement in Biometric
  19. 19. Biometric System Semi-Supervised Template Update Template Editing Template Update with Replacement Template Replacement Results S-o-A summary: Semi-Supervised Template Update Semi-Supervised methods can be summarized by basic operations: 1. Insertion. A “highly genuine” is added into template gallery. 2. Condensing. A template gallery is “fused” in a “super-template”. Main Cons: 1. Sistematic use of Insertion made up long galleries. For real systems Memory and Time of Matching are constrains. 2. Condensing absolves constrains but is less representative of the original template galleries. Replacement is a novel basic operation. Able to: 1. Absolve constrains of Memory and Time of Matching. 2. Assure high level of perfomance. Biagio Freni Template Editing & Replacement in Biometric
  20. 20. Biometric System Semi-Supervised Template Update Template Editing Template Update with Replacement Template Replacement Results Novel Proposal: Replacement Algorithm T c indicates the template gallery of client c. M is the maximum number of template slots allowed. |T c | is the length of client’s gallery. Replacement algorithm consists in the following steps: for each client c = 1..C 1. x ← i, i as novel input 2. s = ms(x, T c ), matching score 3. if s > threshold, “highly genuine” 3.1 if |T c | < M then T c = T c ∪ x 3.2 else T c = replace(T c , x) Function replace is made up according to some criteria. Biagio Freni Template Editing & Replacement in Biometric
  21. 21. Biometric System Semi-Supervised Template Update Template Editing Template Update with Replacement Template Replacement Results Replacement criteria Random Novel template replaces one randomly chosen. Naive Novel template replaces the one nearest to it. FIFO Template galleries are managed as a First In First Out queue. The new element supersede the oldest one. LFU Template galleries are seen as a priority queue Least Frequently Used. Less used template is substituted by novel one. MDIST applied to semi-supervised scenario. A new gallery is created adding by a novel template. MDIST is applied to pruned one element from the gallery. DEND applied in semi-supervised scenario. A new gallery is created adding by a novel template, then, a Dendrogram is made up. Based on Dendrogram an element is removed from the gallery. Biagio Freni Template Editing & Replacement in Biometric
  22. 22. Biometric System Semi-Supervised Template Update Template Editing Template Update with Replacement Template Replacement Results Data sets, Protocol and Perfomance Data sets Results are carried out over 12 public Fingerprint datasets. Each one made up of 100 clients, 8 samples per client, a total of 800 of fingerprint images for dataset. Protocol 50 clients have been selected as system’s users. Other 50 as impostors. For each user 3 sets have been created L, U and T. L refers to user’s template gallery, U as unlabelled coming inputs and T as separeted test. U contains genuine and impostors. Performance Equal Error Rate has been calculated over seven runs. EER represents the error of the verification system when a number of false acceptances is equal to a number of false rejections. Biagio Freni Template Editing & Replacement in Biometric
  23. 23. Biometric System Semi-Supervised Template Update Template Editing Template Update with Replacement Template Replacement Results Results: EER (M = 3) DB FVC2002 algorithm Db1 Db2 Db3 Db4 initial 7.3 6.9 12.1 6.0 update 3.9 3.8 6.5 1.7 RANDOM 5.2 3.4 6.4 2.2 NAIVE 5.0 4.4 7.6 1.5 FIFO 5.5 3.1 6.2 1.9 LFU 4.2 3.1 6.5 1.7 DEND 4.8 5.3 7.0 1.7 MDIST 3.6 3.1 6.3 2.3 Biagio Freni Template Editing & Replacement in Biometric
  24. 24. Biometric System Semi-Supervised Template Update Template Editing Template Update with Replacement Template Replacement Results 6 Results: EER vs gallery dimension M 6 B. Freni, G.L. Marcialis, F. Roli, Replacement algorithms for fingerprint template update, 5th Int. Conf. On Image Analysis and Recognition ICIAR08, June, 25-27, 2008, Povoa de Varzim (Portugal), A. Campihlo and M. Kamel Eds., Springer LNCS 5112, pp. 884-893. Biagio Freni Template Editing & Replacement in Biometric
  25. 25. Biometric System Semi-Supervised Template Update Template Editing Template Update with Replacement Template Replacement Results Summary Results pointed out: 1. Less EER respect to update without replacement has been showed. 2. Perfomance differences among replacement criteria are strong with small “M”. Which means when strong requirements of storing memory is a constrain. 3. MDIST outperfom other criteria, due to the fact that it performs replacement only if it is necessary. Biagio Freni Template Editing & Replacement in Biometric
  26. 26. Biometric System Semi-Supervised Template Update Template Editing Template Update with Replacement Template Replacement Results Conclusions Biometric plays a central role in the problem of security and its importance is going to grow. Template representativeness is the key for the success of a Biometric system. Templates that “best” represent people’s identity must be choosen during “enrollment”, as well during the “authentication”, “highly genuine” must be detected in the coming input queries. Among the whole S-o-A explored in this investigation: 1. the employ of Editing for template selection during enrollment 2. the use of Replacement for template update during authentication Template representativeness is crucial for other important issues in Biometric as Sensor-Interoparability in fingerprint. This problem has been addressed too, but for sake of room this talk was dedicated just to Editing and Replacement. Biagio Freni Template Editing & Replacement in Biometric
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