vii TABLE OF CONTENTS CHAPTER 1 2 TITLE PAGE DECLARATION ii DEDICATION iii ACKNOWLEDGEMENTS iv ABSTRACT v ABSTRAK vi TABLE OF CONTENTS vii LIST OF TABLES x LIST OF FIGURES xi LIST OF ABBREVIATIONS xvi LIST OF SYMBOLS xvii LIST OF APPENDICES xix INTRODUCTION 1 1.1 Introduction 1 1.2 Background of Research 2 1.3 Problem Statements 10 1.4 Research Goal 11 1.5 Objectives of Study 11 1.6 Scope of the Study 12 1.7 List of Research Contributions 13 1.8 Significance of the Study 14 1.9 Research Framework 15 1.10 Thesis Outline 16 LITERATURE REVIEW 18 2.1 18 Introduction viii 2.2 2.3 2.4 2.5 Fingerprint Segmentation 19 2.2.1 Grey-scale Statistical Features 21 2.2.2 Local Directionality Features 22 2.2.3 Coherence Features 24 Fingerprint Enhancement 26 2.3.1 Normalization 28 2.3.2 Gaussian Filter 29 2.3.3 Directional Filter 31 Orientation Field Estimation 34 2.4.1 Orientation Field Estimation Using Gradient 35 2.4.2 Model-based Approach for Orientation Field Estimation 38 Singular Point Detection 40 2.5.1 Poincaré Index Methods 40 2.5.2 Partitioning-based Methods 43 2.5.3 Methods Based on Local Characteristics of the Orientation Field 2.6 3 44 Fingerprint Classification 46 2.6.1 Rule-based Approaches 47 2.6.2 Structure-based Approaches 50 METHODOLOGY 53 3.1 Introduction 53 3.2 Foreground Extraction 56 3.2.1 Grey-scale Normalization 56 3.2.2 Proposed Foreground Extraction Method 59 3.2.3 Noise Areas Identification and Marking Using Gradient Coherence 65 3.3 Enhancement of Grey-level 68 3.4 Fingerprint Orientation Field 73 3.5 Orientation Field Enhancement 75 3.6 Region of Singular Point Detection 78 3.7 Singular Point Detection 82 3.8 A Two-tier Fingerprint Classification Technique 84 ix 3.9 4 3.8.1 The Classification Rule 85 3.8.2 Structure Shape Analysis of Orientation Fields 86 3.8.2.1 Examine True Cores 87 3.8.2.2 Examine True Deltas 92 Summary 95 EXPERIMENTAL RESULT AND DISCUSSION 97 4.1 Introduction 97 4.2 Dataset 97 4.3 Experimental Set-up 102 4.4 Experimental Results 104 4.4.1 Performance Measure of Fingerprint Segmentation 4.4.2 104 Performance Measure of Noise Removal and Ridge Pattern Enhancement for Orientation Field Estimation 4.4.3 Performance Measurement of Singular Point Detection 4.4.4 5 131 Performance Measurement of Fingerprint Classification 4.5 119 Summary 143 155 CONCLUSION 157 5.1 Introduction 157 5.2 Contribution 160 5.3 Future Work 162 REFERENCES 164 Appendices A-G 172- 243 x LIST OF TABLES TABLE NO. TITLE 2.1 Classification based on singularities 2.2 Summary of the fingerprint classification literature review 4.1 46 52 Classes of fingerprint NIST Special Database 14 (f000001 to f027000 filenames) 4.2 PAGE 100 Scan type and sex of fingerprints NIST Special Database 14 (f000001 to f027000 filenames) 101 4.3 Performance measures 103 4.4 Performance results of various fingerprint segmentation methods from singular points detections points of view 114 4.5 Comparison results of singular points detection 143 4.6 A confusion matrix of the experimental results of the proposed fingerprint classification 145 4.7 Ambiguous fingerprints off the misclassified prints 145 4.8 Accuracy rates of the Cappelli and Maltoni’s classification methods using 27,000 fingerprints (f0000001 to f0027000) of DB14 (Source: Cappelli and Maltoni (2009)) 145 xi LIST OF FIGURES FIGURE NO. TITLE PAGE 1.1 Example of five classes 3 1.2 Sample of ambiguous prints 4 1.3 Rejected prints 5 1.4 Dry, wet, and tainted prints 6 1.5 (a) Three fingerprints of the same class that have very different characteristic (large-intra-class variability). (Source: NIST Special Database 14) 7 (b) Three fingerprints belonging to different classes that have similar appearance (small-inter-class variability). (Source: NIST Special Database 14) 7 1.6 Ridges and valleys structure (Right-loop class) 8 1.7 Core and delta on a fingerprint image 9 1.8 Research framework flowchart 17 2.1 A sample of fingerprint segmentation results; (a) Fingerprint image, (b) background regions, foreground regions, and noise patches of the fingerprint image 2.2 Quality of fingerprint image; (a) good, (b) broken/cut, (c) low contrast, (d) dry, (e) wet, and (f) stain 2.3 20 28 Convolution masks; (a) 3× 3 Gaussian smooth filter, (b) 5 × 5 Gaussian smooth filter 30 2.4 Oriented window and x-signature (Hong et al. 1998). 32 2.5 Eight DMF templates (Wu et al., 2004) 33 2.6 A site consists of 3× 3 blocks with the target block V xii in the centre and four overlapping neighbourhood D1 , D 2 , D3 , D 4 (Wang et al. 2005) 2.7 34 Ridge flow direction at pixel (i, j ) and angle θ xy (i, j ) indicating the direction of flow with respect to the horizontal axis 2.8 The labelling of neighbourhood pixels used to explain the Sobel operator 2.9 35 36 Orientation image partitioning with the MASK approach (Cappelli et al., 1999). The intersections between region border lines denote fingerprint singularities 2.10 The mask for capturing the centre point (Hsieh et al. (2005)) 2.11 45 Samples after flow-like tracing (Left-loop, Right-loop and Tented-arch) (Wang and Xie, 2004) 3.1 44 The candidate regions for singular points (Park et al., 2006) 2.12 43 51 On Automatic Fingerprint Classification Scheme (AFCS): Proposed AFCS complements generic AFCS (Note: The dashed rectangle denotes the proposed AFCS) 55 3.2 The fingerprint segmentation scheme 56 3.3 Grey-scale normalization process 57 3.4 Normalization process. (a) Input fingerprint image (NIST DB 14: f0000023), (b) normalized fingerprint image 59 3.5 Flowchart of foreground extraction 60 3.6 (a) Horizontal Sobel mask operator S x ( p, q ) , (b) Vertical Sobel mask operator S y ( p, q ) 3.7 62 Result of the foreground extraction process using the proposed segmentation method. (Note: the input image is referred to normalized image in Figure 3.2(b) above) 65 xiii 3.8 Noise areas of the foreground are identified and labelled. The white coloured blocks indicate the noise areas. (Note: the input image is referred to the extracted foreground image in Figure 3.7 above) 67 3.9 CCB gradient magnitude of size 5 × 5 70 3.10 Result of the enhancement process in the noise areas (circles highlight the noise areas), (a) Orientation image before enhancement, (b) orientation image after the enhancement. (Note: the input is the foreground image in Figure 3.8) 3.11 72 Result of orientation field estimations in the fingerprint image 75 3.12 A 3× 3 CCB of orientation field 76 3.13 Orientation fields of fingerprint after enhancement using minimum variance of orientation fields. 77 3.14 Set of four pre-defined block of arches. 78 3.15 The mechanics of BoI 80 3.16 Results of CRSP using the proposed method. (Source image: NIST Database 14, f0000023). Note: Blue squares indicate CRSP 3.17 82 Core and delta detections using the proposed methods (NIST DB 14: F0000023). Note: White and yellow squares indicate the core and delta, respectively 3.18 Types of the core point (a) Upper-core, (b) lower-core, (c) right-core, and (d) left-core 3.19 84 88 Omni-directional orientation fields neighbouring the core points: (a) Upper-core, (b) lower-core, (c) rightcore, and (d) left- core 3.20 90 Omni-directional orientation fields neighbouring a delta. (a) Right-delta, and (b) left-delta 93 4.1 Tagged comment in WSQ compressed file 99 4.2 Scar fingerprint 100 xiv 4.3 Fingerprint with a cross-referenced classification or ambiguous fingerprint 4.4 101 Fingerprint with extraneous objects: (a) Like handwritten characters and (b) other artefacts common to inked fingerprints 4.5 (a) - (e): Results of the segmentation process of good quality fingerprints 4.6 109 (a) - (e): Results of the segmentation process of low contrast fingerprints 4.9 107 (a) - (e): Results of the segmentation process of wet fingerprints 4.8 106 (a) - (e): Results of the segmentation process of dry fingerprints 4.7 102 111 (a) - (e): Results of the segmentation process of fingerprints which contain ink stains and handwritten characters 4.10 112 On segmentation results: Local mean versus the proposed method. (a) Original fingerprint; (a1) outcome of local mean method; (a2) outcome of proposed method 4.11 116 On segmentation results: Zang and Yan versus the proposed method. (b) Original fingerprint; (b1) outcome of Zang and Yan method; (b2) outcome of proposed method 4.12 117 On segmentation results: Local variance of gradient magnitude method Vs the proposed method. (c) Original fingerprint; (c1) outcome of local variance of gradient magnitude method; (c2) outcome of the proposed method 4.13 118 On segmentation results: Outcome of the proposed segmentation method. (d) Original fingerprint; (d1) outcome of the proposed method 4.14 (a) - (e): Some results of the enhancement process for good quality fingerprints 4.15 118 121 (a) - (e): Some results of the enhancement process for dry fingerprints 122 xv 4.16 (a) - (e): Some results of the enhancement process for wet fingerprints 4.17 (a) - (e): Some results of the enhancement process for cuts fingerprints 4.18 126 (a) - (e): Some results of the enhancement process for bruises fingerprints 4.19 124 127 (a) - (e): Some results of the enhancement process for Low contrast fingerprints 129 4.20 Artificial singular point regions 130 4.21 Mean square error results of both Wang and the proposed methods 4.22 (a) - (e): Results of the singular points detection for good fingerprints 4.23 140 (a) - (e): Results of the singular points detection for low contrast fingerprints 4.28 138 (a) - (e): Results of the singular points detection for bruises fingerprints 4.27 137 (a) - (e): Results of the singular points detection for cuts fingerprints 4.26 135 (a) - (e): Results of the singular points detection for wet fingerprints 4.25 133 (a) - (e): Results of the singular points detection for dry fingerprints 4.24 131 142 Some examples of correctly classified prints of various qualities viz. good, dry, wet, cut, bruise, low contrast, and stain 148 4.29 Fake core (file name: f0002084) 149 4.30 (a) - (c): Fingerprints classes with one missing delta. 150 4.31 A sample of large-intra-class variation prints 152 4.32 Small-inter-class variations 154 4.33 Poor quality fingerprints 155 xvi LIST OF ABBREVIATIONS FBI - Federal Bureau Investigation AFIS - Automatic Fingerprint Identification System AFCS - Automatic Fingerprint Classification System NIST - National Institute of Standards and Technology NN - Neural Network HMM - Hidden Markov Model 2D - Two dimensional DMF - Directional Median Filter DB14 - NIST Special Database 14 SVM - Support Vector Machine FVC2002 - Second International Competition for Fingerprint Verification Algorithm CCB - Cross Centre Block BoI - Block of Interest CB - Convergence Block CRSP - Candidate Region Singular Point GoB - Group of Block CoB - Combination of Block NCIC - National Crime Information Centre WSQ - Wavelet Scalar Quantisation MC - Miss Rate of Cores MD - Miss Rate of Deltas FC - False alarm rate of Cores FD - False alarm rate of Deltas MSE - Mean Square Error xvii LIST OF SYMBOLS I (m, n) - Intensity value of the pixel at the m-th row and n-th column in the fingerprint image W ×H - Size of fingerprint image Mg - Global mean value of fingerprint image Vg - Global variance value of fingerprint image N (m, n) - Intensity value of the pixel at the m-th row and n-th column in the normalized fingerprint image Mg 0 - Desired mean value for determine normalization Vg 0 - Desired variance value for determine normalization Mn - Global mean value of normalized fingerprint image B×B - Size of block in the fingerprint image Mb(i, j ) - Local mean value of block (i, j ) Gx (m, n) - Gradient of pixel (m, n) in horizontal direction G y (m, n) - Gradient of pixel (m, n) in vertical direction Sx - Horizontal Sobel mask operator Sy - Vertical Sobel mask operator Gr (m, n) - Gradient magnitude of pixel (m, n) Gth - Threshold value for gradient c - Threshold factor for gradient Mgr (i, j ) - Local mean value of gradient magnitude of block (i, j ) Vgr (i, j ) - Local variance value of gradient magnitude of block (i, j ) Coh(i, j ) - Coherence value of block (i, j ) Vx (i, j ) - Vector gradient x-direction of block (i, j ) Vy (i, j ) - Vector gradient y-direction of block (i, j ) xviii Vz (i, j ) - Vector gradient resultant direction of block (i, j ) D - Set of gradient magnitude in CCB Di - Subset i-th of gradient magnitude in CCB Mgm Di - Mean value of subset i-th of gradient magnitude in CCB Vgm Di - Variance value of subset i-th of gradient magnitude in CCB P - Set of normalized fingerprint image in CCB Pi - Subset i-th of normalized fingerprint image in CCB Mi Pi - Mean value of subset i-th of normalized fingerprint image in CCB Q - Set of gradient angle in CCB Qi - Subset i-th of gradient angle in CCB Ma Qi - Mean value of subset i-th of gradient angle in CCB Va Qi - Variance value of subset i-th of gradient angle in CCB Gs( p, q) - Gaussian filtering mask θ (i, j ) - Gradient angle of orientation field δ (k ) - Closed-curve angle PI - Poincaré index in continuous vector P(i, j ) - Poincaré index in discrete vector Nc - Number of cores Nd - Number of deltas xix LIST OF APPENDICES APPENDIX TITLE A Scars Fingerprint Image B Results of Fingerprint Segmentation using Local Mean Method C G 195 207 Results of Fingerprint Segmentation using Proposed Method F 183 Results of Fingerprint Segmentation using Local Variance of Gradient Magnitude E 172 Results of Fingerprint Segmentation using a Combination of Local Mean and Coherence D PAGE 219 Results of Singular Points Detection using Poincaré Index Method 231 List of Publications 243