Face Detection and Modeling for Recognition - Biometrics Research ...

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Local feature refinement follows local alignment to further adapt the aligned face model to an individual face by using 2.5D active contours (snakes). We modify Amini et al.’s [124] 2D snakes for our 3D active contours on boundaries of facial features. The active contours are useful for detecting irregular shapes by minimizing the (total) energy of the shape contour. The total energy, E total , consists of the internal energy E int (controlling the geometry of the contour) and external energy E ext (controlling the desired shape). We reformulate the energy for our 3D snake as follows. Assume that an active contour includes a set of N vertices: {v 1 , · · · , v i−1 , v i , v i+1 , · · · , v N }. The total energy can be computed by Eq. (4.2). E total = N∑ [E int (v i ) + E ext (v i )] . (4.2) i=1 The internal energy is listed in Eq. (4.3). E int (v i ) = ( α i |v i − v i−1 | 2 + β i |v i+1 − 2v i + v i−1 | 2) /2, (4.3) where α i controls the distance between vertices, and β i controls the smoothness of the contours. The norm term | · | in Eq. (4.3) is determined by parameterized 3D coordinates, not merely 2D coordinates. Therefore, we call these contours 2.5D snakes. The initial contours needed for fitting the snakes are crucial. Fortunately, they can be obtained from our generic face model. Another important point for fitting snakes 106
is to find appropriate external energy maps that contain local maximum/minimum at the boundaries of facial features. For the face boundary and the nose, the external energy is computed by the maximum magnitude of vertical and horizontal gradients from range maps. These two facial features have steeper borders than others. For features such as eyes and the mouth, the external energy is obtained by a product of the magnitude of the luminance gradient and the squared luminance. Figure 4.9 (a) (b) (c) Figure 4.9. Local feature refinement: initial (in blue) and refined (in red) contours overlaid on the energy maps for (a) the face boundary; (b) the nose; (c) the left eye; and (d) the mouth. 107 (d)
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Face Detection and Modeling for Rec
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perimental results demonstrate succ
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To my parents; my lovely wife, Pei-
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for providing the range datasets; t
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4 Face Modeling 97 4.1 Modeling Met
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List of Figures 1.1 Applications us
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2.6 A breakdown of face recognition
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4.2 3D triangular-mesh model and it
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5.14 Fine alignment using geodesic
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Chapter 1 Introduction In recent ye
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(a) (b) Figure 1.1. Applications us
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(e) Figure 1.1. (Cont’d). (f) (a)
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esolutions and of poor quality (i.e
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can recognize known faces in carica
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the motivation for studies that att
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(a) Figure 1.10. Similarity of fron
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verify the face present in an image
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17 Figure 1.12. System diagram of o
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algorithm can also provide geometri
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commercial parametric face modeling
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1.5.1 Face Alignment Using 2.5D Sna
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1.5.3 Face Alignment Using Interact
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Using merely low-level features (e.
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such as eyes, mouth and face bounda
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can be applied to a 3D face model w
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Chapter 2 Literature Review We firs
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mation theory, geometrical modeling
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(e) (f) (g) (h) (i) (j) (k) (l) Fig
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esult in different recognition appr
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(a) (b) (c) Figure 2.2. Examples of
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(a) (b) (c) (d) Figure 2.4. Interna
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Figure 2.6. A breakdown of face rec
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2.3 Face Modeling Face modeling pla
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An advanced modeling approach which
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tionals to minimize, implementation
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are listed in Table 2.2. All of the
Page 73 and 74: low-level features can provide mean
Page 75 and 76: holistic 2D and geometrical 3D feat
Page 77 and 78: size) to generate potential face ca
Page 79 and 80: oundary. A face score is computed f
Page 81 and 82: normalized red-green (r-g) space [1
Page 83 and 84: (a) (b) Figure 3.3. The Y C b C r c
Page 85 and 86: (a) Figure 3.5. 2D projections of t
Page 87 and 88: 3.3 Localization of Facial Features
Page 89 and 90: (a) (b) (c) Figure 3.9. Constructio
Page 91 and 92: The eye map from the chroma is enha
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Page 95 and 96: Figure 3.12. Computation of face bo
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Page 99 and 100: segment. The other term favors an u
Page 101 and 102: (a) (b) (c) (d) (e) Figure 3.15. Fa
Page 103 and 104: (a) (b) (c) (d) (e) Figure 3.18. Fa
Page 105 and 106: The number of false positives is al
Page 107 and 108: (a) (b) (c) (d) Figure 3.20. Face d
Page 109 and 110: Figure 3.22. Face detection results
Page 111 and 112: Figure 3.22. (Cont’d). 93
Page 113 and 114: 3.5 Summary We have presented a fac
Page 115 and 116: Chapter 4 Face Modeling We first in
Page 117 and 118: and nose in frontal views), and bec
Page 119 and 120: 4.3 Facial Measurements Facial meas
Page 121 and 122: 4.4 Model Construction Our face mod
Page 123: a feature-dependent decay factor. F
Page 127 and 128: (a) (b) (d) (e) (f) Figure 4.11. Te
Page 129 and 130: Chapter 5 Semantic Face Recognition
Page 131 and 132: (a) (b) (c) Figure 5.1. Semantic fa
Page 133 and 134: of Fourier series truncation. In ad
Page 135 and 136: ponent color. The semantic facial s
Page 137 and 138: (a) (b) (c) (d) Figure 5.5. Boundar
Page 139 and 140: (a) (b) (c) (d) Figure 5.7. Coarse
Page 141 and 142: In the Baysian framework, given an
Page 143 and 144: edge map; hence it requires a clean
Page 145 and 146: shows examples of mouth energies. F
Page 147 and 148: [ ( ∂Φ ∂t =∇Φ µ 1 div(g
Page 149 and 150: (a) (b) (c) (d) (e) (f) Figure 5.14
Page 151 and 152: y the reliability of component matc
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Page 155 and 156: (a) (b) (c) (d) Figure 5.18. Exampl
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Page 159 and 160: (a) (b) (c) (d) (e) (f) (g) Figure
Page 161 and 162: 5.6 Summary For overcoming variatio
Page 163 and 164: such vision-based systems are (i) d
Page 165 and 166: 6.2 Future Directions Based on the
Page 167 and 168: (a) (b) (c) (d) Figure 6.2. An exam
Page 169 and 170: • Non-frontal training views: Acc
Page 171 and 172: Appendices
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and are shown as blue-dashed lines
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adius of a cluster ‘i’ w.r.t. a
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Appendix C Image Processing Templat
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considering pixel classes as voxel
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gray8imageA(120,120) = 200; // Asse
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Bibliography [1] Visionics Corporat
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[32] L. Wiskott, J.M. Fellous, N. K
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[59] M. Grudin, “On internal repr
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[84] M. Abdel-Mottaleb and A. Elgam
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[113] B. Kim and P. Burger, “Dept
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[141] M.D. Adams and F. Kossentini,
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[169] P.T. Jackway and M. Deriche,
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