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Face Image Analysis:Recognition and Presentation Attack Detection
Shervin R. Arashloo
March 12, 2021
Shervin R. Arashloo Face Image Analysis March 12, 2021 1 / 41
Outline
1 Face RecognitionGraph MatchingStatistical Shape PriorMultiresolution and parallel optimisationClass-specific Discriminant Analysis
2 Face Presentation Attack DetectionOne-Class FormulationClient-specific one-class learningClassifier FusionOne-Class Fisher Discriminant AnalysisKernel Fusion
Shervin R. Arashloo Face Image Analysis March 12, 2021 2 / 41
Face Recognition Major Challenges
Pose (out-of-plane rotation)
Illumination
Expression
etc.
Shervin R. Arashloo Face Image Analysis March 12, 2021 3 / 41
Deformable Matching
Object Recognition and Matching
Bag of words
Discarding relational information between object primitives
Graph matching
Incorporating structural information for matching
Shervin R. Arashloo Face Image Analysis March 12, 2021 4 / 41
Graphs and Hypergraphs
Nodes represent object primitives
Edges/hyperedges encode their dependencies
Shervin R. Arashloo Face Image Analysis March 12, 2021 5 / 41
Deformation Model
E (x ; θ) =∑u∈V
θu(xu) +∑
(u,v)∈E
θuv (xu, xv )
labels are 2D displacements
θu measures the degree of similarity between graylevel contents of twoblocks
θuv enforces smoothness over deformation map
Shervin R. Arashloo Face Image Analysis March 12, 2021 6 / 41
Decomposed Model
Complexity: O(νL2)L: Cardinality of the label set for the horizontal and vertical displacementsν: Number of nodesThe complexity scales quadratically in number of labels!
Decomposed model: modelling horizontal and vertical labels separately
Complexity of the decomposed model: O(νL)scales linearly in number of labels.
Shervin R. Arashloo Face Image Analysis March 12, 2021 7 / 41
Decomposed Model
Complexity: O(νL2)L: Cardinality of the label set for the horizontal and vertical displacementsν: Number of nodesThe complexity scales quadratically in number of labels!
Decomposed model: modelling horizontal and vertical labels separately
Complexity of the decomposed model: O(νL)scales linearly in number of labels.
Shervin R. Arashloo Face Image Analysis March 12, 2021 7 / 41
Statistical Shape Prior
Deformable models are broadly classified into two categories:
Free-form
Only general continuity and smoothness constraints are considered; can bematched to an arbitrary shape (e.g. Snake Model)
Parametric
Incorporate a general shape of the object of interest and encode specialattributes of an object and its variations-are more robust to occlusions andspurious structures (e.g. Active Shape Model)
Shervin R. Arashloo Face Image Analysis March 12, 2021 8 / 41
Deformation Energy
The updated objective function:
E (x ; θ) =∑s∈V
θs(xs) +∑
(s,u)∈E
θsu(xs , xu)+θg (x)
where
θg (x) measures deviation from mean shape in the PCA space
Shervin R. Arashloo Face Image Analysis March 12, 2021 9 / 41
Multiresolution Optimisation: Supercoupling Approach
Moving from coarser towardsfiner scales
Challenge: maintaining aconsistency between energyfunctions at different scales
The Supercoupling algorithm consists of two main steps:renormalisation and processing.
Renormalisation
Iteratively constructing coarser and coarser grids of nodes and acorresponding sequence of energy functions
Processing
Performing a multi-scale coarse-to-fine optimisation starting from thecoarsest scale moving towards the finest one
Shervin R. Arashloo Face Image Analysis March 12, 2021 10 / 41
Multiresolution Optimisation: Supercoupling Approach
Moving from coarser towardsfiner scales
Challenge: maintaining aconsistency between energyfunctions at different scales
The Supercoupling algorithm consists of two main steps:renormalisation and processing.
Renormalisation
Iteratively constructing coarser and coarser grids of nodes and acorresponding sequence of energy functions
Processing
Performing a multi-scale coarse-to-fine optimisation starting from thecoarsest scale moving towards the finest one
Shervin R. Arashloo Face Image Analysis March 12, 2021 10 / 41
Optimisation: Dual Decomposition
Two steps:
Decompose the problem into anumber of subproblems andsolve each one separately
Enforce consistency betweensubproblems
A large number of independently solvable subproblems motivate a parallelprocessing!
Graphical Processing Units
Array of highly threaded streaming multiprocessors
High speed shared memory visible to all processing elements as wellas a number of other types of memory
Shervin R. Arashloo Face Image Analysis March 12, 2021 11 / 41
Optimisation: Dual Decomposition
Two steps:
Decompose the problem into anumber of subproblems andsolve each one separately
Enforce consistency betweensubproblems
A large number of independently solvable subproblems motivate a parallelprocessing!
Graphical Processing Units
Array of highly threaded streaming multiprocessors
High speed shared memory visible to all processing elements as wellas a number of other types of memory
Shervin R. Arashloo Face Image Analysis March 12, 2021 11 / 41
Optimisation: Dual Decomposition
Two steps:
Decompose the problem into anumber of subproblems andsolve each one separately
Enforce consistency betweensubproblems
A large number of independently solvable subproblems motivate a parallelprocessing!
Graphical Processing Units
Array of highly threaded streaming multiprocessors
High speed shared memory visible to all processing elements as wellas a number of other types of memory
Shervin R. Arashloo Face Image Analysis March 12, 2021 11 / 41
Speed-up Gains
Parallel Processing ∼ 24x
Multiresolution Analysis ∼ 5x
Other Techniques ∼ 1.8x
Overall ∼ 218x
Shervin R. Arashloo Face Image Analysis March 12, 2021 12 / 41
Some Matching Results
Shervin R. Arashloo Face Image Analysis March 12, 2021 13 / 41
Class-specific Discriminant Analysis
Subspace methods:
PCA, LDA, etc. (insufficiency of linear models)
Kernel methods: KPCA, KDA, etc.
Class-Specific Kernel Discriminant Analysis
Learns a class from a single labelled example (one-shot learning)
Results in subject-specific projections
Shervin R. Arashloo Face Image Analysis March 12, 2021 14 / 41
Class-specific Discriminant Analysis
Subspace methods:
PCA, LDA, etc. (insufficiency of linear models)
Kernel methods: KPCA, KDA, etc.
Class-Specific Kernel Discriminant Analysis
Learns a class from a single labelled example (one-shot learning)
Results in subject-specific projections
Shervin R. Arashloo Face Image Analysis March 12, 2021 14 / 41
Classification
Conventional hand-crafted descriptors used:
Local Binary Pattern (LBP)
Local Phase Quantisation (LPQ)
Binarised Statistical Image Features (BSIF)
For classification:
Kernel fusion over the three descriptors
Correspondences are taken into account
Shervin R. Arashloo Face Image Analysis March 12, 2021 15 / 41
Labelled Faces in the Wild (LFW) Dataset
Real world variations of facial images such as pose, illumination,expression, occlusion, low resolution, blur, etc.Contains 13,233 images of 5,749 subjectsPair-matching problem
Figure: Sample images from the LFW dataset.
Shervin R. Arashloo Face Image Analysis March 12, 2021 16 / 41
Evaluation Protocols
Shervin R. Arashloo Face Image Analysis March 12, 2021 17 / 41
Results: Unsupervised
Shervin R. Arashloo Face Image Analysis March 12, 2021 18 / 41
Results: Image-Restricted, No Outside Data
Shervin R. Arashloo Face Image Analysis March 12, 2021 19 / 41
Observations
In the most relaxed scenario, state-of-the-art deep methods achievemore than 98% accuracy
Very large labelled data required to exploit the potential of deepnetworks
Graph-based methods very efficient in terms of the number of trainingdata
Typically high performance computing resources required to traindeep nets
Computationally demanding MAP inference in MRF vs. relatively fastoutput generation in deep networks
Shervin R. Arashloo Face Image Analysis March 12, 2021 20 / 41
Journal Articles Relevant to Face Recognition
Arashloo, S.R. and Kittler, J., ”Energy Normalization for Pose-Invariant Face Recognition Based on MRF Model ImageMatching”, Pattern Analysis and Machine Intelligence, IEEE Transactions on, vol. 33, no. 6, pp. 1274-1280, Jun. 2011.
Arashloo, S.R., Kittler, J. and Christmas, W.J., ”Pose-Invariant Face Recognition by Matching on MultiresolutionMRFs Linked by Super-coupling Transform”, Computer Vision and Image Understanding , Elsevier, special issue ongraph-based representations in computer vision, vol. 115, issue 7, pp. 1073-1083, July 2011.
Arashloo, S.R. and Kittler, J., ”Fast Pose Invariant Face Recognition Using Supercoupled Multi-resolution MarkovRandom Fields on a GPU”, Pattern Recognition Letters, Elsevier, special issue on celebrating the life and work of MariaPetrou, vol. 48, pp. 49-59, Oct. 2014.
Arashloo, S.R. and Kittler, J., ”Class-Specific Kernel Fusion of Multiple Descriptors for Face Verification UsingMultiscale Binarised Statistical Image Features”, Information Forensics and Security, IEEE Transactions on, special issueon facial biometrics in the wild, vol. 9, no.12, pp. 2100-2109, Dec. 2014.
Arashloo, S.R., ”Incorporating Point Distribution Model Priors into MRFs Using Convex Quadratic Programming”,Machine Vision and Applications, Springer, vol. 27, no. 6, pp. 821-832, Aug. 2016.
Arashloo, S.R., ”A Comparison of Deep Multilayer Networks and MRF Matching Models for Face Recognition in theWild”, Computer Vision, IET , vol. 10, no. 6, pp. 466-474, Sep. 2016.
Arashloo, S.R., ”Multiscale Binarised Statistical Image Features for Symmetric Face Matching Using MultipleDescriptor Fusion Based on Class-Specific LDA”, Pattern Analysis and Applications, Springer, pp. 1-14, May 2015.
Shervin R. Arashloo Face Image Analysis March 12, 2021 21 / 41
Face Presentation Attack Detection
Problem:An unauthorised subject tries to get illegitimate access to a facerecognition system by presenting fake biometrics traits
Typical presentation attack instruments:
Video Replay
Mask
etc.
Shervin R. Arashloo Face Image Analysis March 12, 2021 22 / 41
Face Presentation Attack Detection
Problem:An unauthorised subject tries to get illegitimate access to a facerecognition system by presenting fake biometrics traits
Typical presentation attack instruments:
Video Replay
Mask
etc.
Shervin R. Arashloo Face Image Analysis March 12, 2021 22 / 41
Points of Attack to a Biometrics System
Shervin R. Arashloo Face Image Analysis March 12, 2021 23 / 41
Samples captured by a recognition system
(a) corresponds to genuine (bona fide) samples(b),(c) and (d) represent presentation attacks 1
1images from the ”MSU Mobile Face Spoofing Database (MSU MFSD)” dataset.
Shervin R. Arashloo Face Image Analysis March 12, 2021 24 / 41
Samples captured by a recognition system
(a) corresponds to genuine (bona fide) samples(b),(c) and (d) represent presentation attacks 1
1images from the ”MSU Mobile Face Spoofing Database (MSU MFSD)” dataset.
Shervin R. Arashloo Face Image Analysis March 12, 2021 24 / 41
Conventional approach
The Conventional approach is Two-Class Classification:
Training samples include both bona-fide (genuine) and attack samples
A binary classifier is trained to classify an image (sequence) as eitherbona-fide or attack
Drawbacks:
High cost of collecting attack samples
Low generalisation
Different imaging conditionsNovel attack types unseen during training!
Shervin R. Arashloo Face Image Analysis March 12, 2021 25 / 41
Conventional approach
The Conventional approach is Two-Class Classification:
Training samples include both bona-fide (genuine) and attack samples
A binary classifier is trained to classify an image (sequence) as eitherbona-fide or attack
Drawbacks:
High cost of collecting attack samples
Low generalisation
Different imaging conditionsNovel attack types unseen during training!
Shervin R. Arashloo Face Image Analysis March 12, 2021 25 / 41
One-Class Formulation of Face PAD problem
Genuine samples considered as target observations and attacks asanomalies
Our approach learns from genuine data only: not biased towardsspecific attack types!
Goal: Characterise the support domain of probability density function ofgenuine samples
Shervin R. Arashloo Face Image Analysis March 12, 2021 26 / 41
One-Class Formulation of Face PAD problem
Genuine samples considered as target observations and attacks asanomalies
Our approach learns from genuine data only: not biased towardsspecific attack types!
Goal: Characterise the support domain of probability density function ofgenuine samples
Shervin R. Arashloo Face Image Analysis March 12, 2021 26 / 41
Presentation Attack Detection: Common approach
The common approach is Subject-Independent Detection:
A common classifier is trained to detect PA w.r.t. all subjects
Drawback:
Ignores any class-specific information useful for PAD
Shervin R. Arashloo Face Image Analysis March 12, 2021 27 / 41
Client-specific modelling
Deploying client-specific information for face spoofing detection
Subject-specific score distributions motivate a distinct threshold foreach client
Shervin R. Arashloo Face Image Analysis March 12, 2021 28 / 41
Shervin R. Arashloo Face Image Analysis March 12, 2021 29 / 41
Classifier Fusion
Motivation: Different one-class learners+diverse representations
2
2J. Kittler, M. Hatef, R. P. W. Duin and J. Matas, ”On combining classifiers,” in IEEE Transactions on Pattern Analysis
and Machine Intelligence, vol. 20, no. 3, pp. 226-239, March 1998, doi: 10.1109/34.667881.
Shervin R. Arashloo Face Image Analysis March 12, 2021 30 / 41
Classifier Fusion
Motivation: Different one-class learners+diverse representations
2
2J. Kittler, M. Hatef, R. P. W. Duin and J. Matas, ”On combining classifiers,” in IEEE Transactions on Pattern Analysis
and Machine Intelligence, vol. 20, no. 3, pp. 226-239, March 1998, doi: 10.1109/34.667881.
Shervin R. Arashloo Face Image Analysis March 12, 2021 30 / 41
Diversity in Experts
Multiple regions:
Multiple Deep CNN’s:
GoogleNet
ResNet50
VGG16
Multiple One-class learners:
One-class Support Vector Data Description
Mahalanobis distance
Gaussian mixture model
Shervin R. Arashloo Face Image Analysis March 12, 2021 31 / 41
The Impact of Classifier Fusion
Shervin R. Arashloo Face Image Analysis March 12, 2021 32 / 41
One-Class Fisher Discriminant Analysis
The Fisher classifier:
F(β) =β>Σbβ
β>Σwβ
Σb: between-class scatter matrixΣw : within-class scatter matrixβ: the Fisher discriminant
Originally developed for two-classclassification but can be adapted to aone-class setting!
Shervin R. Arashloo Face Image Analysis March 12, 2021 33 / 41
One-Class Fisher Discriminant Analysis
The Fisher classifier:
F(β) =β>Σbβ
β>Σwβ
Σb: between-class scatter matrixΣw : within-class scatter matrixβ: the Fisher discriminant
Originally developed for two-classclassification but can be adapted to aone-class setting!
Shervin R. Arashloo Face Image Analysis March 12, 2021 33 / 41
One-Class Fisher Discriminant Analysis
The Fisher classifier:
F(β) =β>Σbβ
β>Σwβ
Σb: between-class scatter matrixΣw : within-class scatter matrixβ: the Fisher discriminant
Originally developed for two-classclassification but can be adapted to aone-class setting!
Shervin R. Arashloo Face Image Analysis March 12, 2021 33 / 41
Regression-Based Formulation
Solving for the Fisher discriminant requires costly eigendecompositionof dense matrices
Not convenient to impose regularisation on the discriminant forimproved generalisation performance
Regularised regression-based reformulation in the Hilbert space
minθ‖θ‖2
2 +δ
n
n∑i=1
(1− θ>υ(xi ))2
Tikhonov regularisation
Or its dual problem as
maxω−ω>Kω − σω>ω + 2ω>1
σ = n/δK: kernel matrix1: denotes an n-dimensional vector of ones
Shervin R. Arashloo Face Image Analysis March 12, 2021 34 / 41
Regression-Based Formulation
Solving for the Fisher discriminant requires costly eigendecompositionof dense matrices
Not convenient to impose regularisation on the discriminant forimproved generalisation performance
Regularised regression-based reformulation in the Hilbert space
minθ‖θ‖2
2 +δ
n
n∑i=1
(1− θ>υ(xi ))2
Tikhonov regularisation
Or its dual problem as
maxω−ω>Kω − σω>ω + 2ω>1
σ = n/δK: kernel matrix1: denotes an n-dimensional vector of ones
Shervin R. Arashloo Face Image Analysis March 12, 2021 34 / 41
Regression-Based Formulation
Solving for the Fisher discriminant requires costly eigendecompositionof dense matrices
Not convenient to impose regularisation on the discriminant forimproved generalisation performance
Regularised regression-based reformulation in the Hilbert space
minθ‖θ‖2
2 +δ
n
n∑i=1
(1− θ>υ(xi ))2
Tikhonov regularisation
Or its dual problem as
maxω−ω>Kω − σω>ω + 2ω>1
σ = n/δK: kernel matrix1: denotes an n-dimensional vector of ones
Shervin R. Arashloo Face Image Analysis March 12, 2021 34 / 41
Regression-Based Formulation
Solving for the Fisher discriminant requires costly eigendecompositionof dense matrices
Not convenient to impose regularisation on the discriminant forimproved generalisation performance
Regularised regression-based reformulation in the Hilbert space
minθ‖θ‖2
2 +δ
n
n∑i=1
(1− θ>υ(xi ))2
Tikhonov regularisation
Or its dual problem as
maxω−ω>Kω − σω>ω + 2ω>1
σ = n/δK: kernel matrix1: denotes an n-dimensional vector of ones
Shervin R. Arashloo Face Image Analysis March 12, 2021 34 / 41
Regression-Based Formulation
Solving for the Fisher discriminant requires costly eigendecompositionof dense matrices
Not convenient to impose regularisation on the discriminant forimproved generalisation performance
Regularised regression-based reformulation in the Hilbert space
minθ‖θ‖2
2 +δ
n
n∑i=1
(1− θ>υ(xi ))2
Tikhonov regularisation
Or its dual problem as
maxω−ω>Kω − σω>ω + 2ω>1
σ = n/δK: kernel matrix1: denotes an n-dimensional vector of ones
Shervin R. Arashloo Face Image Analysis March 12, 2021 34 / 41
Kernel Fusion
Fusing multiple representations via a sum rule:K = K1 + K2 + · · ·+ KJ
Diversity in the representationsMultiple Regions
Different Deep CNN’s
GoogleNetResNet50VGG16
Shervin R. Arashloo Face Image Analysis March 12, 2021 35 / 41
Kernel Fusion Evaluation Results
Unseen attack evaluation protocol
Shervin R. Arashloo Face Image Analysis March 12, 2021 36 / 41
Multiple Kernel Learning
The ideaInstead of using fixed combination rules, learn linear combination weights
Objective function
minβ
maxα
−α>(∑J
j=1 βjKj)α− δα>α+ 2α>1
s.t. β ≥ 0,R(β)
kernel weights
Different possibilities for regularisation R(β):
`p-norm ‖β‖pp ≤ 1; p ≥ 1
induces sparsity
mixed (r , p)-norm∥∥ββ>∥∥
r ,p≤ 1; r , p ≥ 1
induces sparsityenables interaction between kernels
Both regularisations lead to convex optimisation problems!
Shervin R. Arashloo Face Image Analysis March 12, 2021 37 / 41
Multiple Kernel Learning
The ideaInstead of using fixed combination rules, learn linear combination weights
Objective function
minβ
maxα
−α>(∑J
j=1 βjKj)α− δα>α+ 2α>1
s.t. β ≥ 0,R(β)
kernel weights
Different possibilities for regularisation R(β):
`p-norm ‖β‖pp ≤ 1; p ≥ 1
induces sparsity
mixed (r , p)-norm∥∥ββ>∥∥
r ,p≤ 1; r , p ≥ 1
induces sparsityenables interaction between kernels
Both regularisations lead to convex optimisation problems!
Shervin R. Arashloo Face Image Analysis March 12, 2021 37 / 41
Multiple Kernel Learning
The ideaInstead of using fixed combination rules, learn linear combination weights
Objective function
minβ
maxα
−α>(∑J
j=1 βjKj)α− δα>α+ 2α>1
s.t. β ≥ 0,R(β)
kernel weights
Different possibilities for regularisation R(β):
`p-norm ‖β‖pp ≤ 1; p ≥ 1
induces sparsity
mixed (r , p)-norm∥∥ββ>∥∥
r ,p≤ 1; r , p ≥ 1
induces sparsityenables interaction between kernels
Both regularisations lead to convex optimisation problems!
Shervin R. Arashloo Face Image Analysis March 12, 2021 37 / 41
Multiple Kernel Learning
The ideaInstead of using fixed combination rules, learn linear combination weights
Objective function
minβ
maxα
−α>(∑J
j=1 βjKj)α− δα>α+ 2α>1
s.t. β ≥ 0,R(β)
kernel weights
Different possibilities for regularisation R(β):
`p-norm ‖β‖pp ≤ 1; p ≥ 1
induces sparsity
mixed (r , p)-norm∥∥ββ>∥∥
r ,p≤ 1; r , p ≥ 1
induces sparsityenables interaction between kernels
Both regularisations lead to convex optimisation problems!
Shervin R. Arashloo Face Image Analysis March 12, 2021 37 / 41
Multiple Kernel Learning
The ideaInstead of using fixed combination rules, learn linear combination weights
Objective function
minβ
maxα
−α>(∑J
j=1 βjKj)α− δα>α+ 2α>1
s.t. β ≥ 0,R(β)
kernel weights
Different possibilities for regularisation R(β):
`p-norm ‖β‖pp ≤ 1; p ≥ 1
induces sparsity
mixed (r , p)-norm∥∥ββ>∥∥
r ,p≤ 1; r , p ≥ 1
induces sparsityenables interaction between kernels
Both regularisations lead to convex optimisation problems!
Shervin R. Arashloo Face Image Analysis March 12, 2021 37 / 41
Multiple Kernel Learning
The ideaInstead of using fixed combination rules, learn linear combination weights
Objective function
minβ
maxα
−α>(∑J
j=1 βjKj)α− δα>α+ 2α>1
s.t. β ≥ 0,R(β)
kernel weights
Different possibilities for regularisation R(β):
`p-norm ‖β‖pp ≤ 1; p ≥ 1
induces sparsity
mixed (r , p)-norm∥∥ββ>∥∥
r ,p≤ 1; r , p ≥ 1
induces sparsityenables interaction between kernels
Both regularisations lead to convex optimisation problems!
Shervin R. Arashloo Face Image Analysis March 12, 2021 37 / 41
Abnormality and Novelty Detection
Abnormality Detectiondetect abnormal observations whenthe classifier is trained using a set ofnormal samples of the correspondingclass
Novelty Detectionassess the novelty of a new samplebased on previously observed samples
Figure: (a) Abnormal image detection: Top three rows arenormal images from the PASCAL dataset. Bottom three rowsare abnormal images from the Abnormal 1001 dataset. (b)Novelty detection: images from the Caltech256 dataset.
Shervin R. Arashloo Face Image Analysis March 12, 2021 38 / 41
`p-norm Evaluation Results
Shervin R. Arashloo Face Image Analysis March 12, 2021 39 / 41
(r , p)-norm Evaluation Results
Shervin R. Arashloo Face Image Analysis March 12, 2021 40 / 41
Journal Articles Relevant to Presentation Attack Detection
Arashloo, S.R. and Kittler, J., ”An Anomaly Detection Approach to Face Spoofing Detection: A New Formulation andEvaluation Protocol”, IEEE Access, vol. 5, pp. 13868-13882, 2017.
Arashloo, S.R. and Kittler, J., ”Robust One-Class Kernel Spectral Regression”,Neural Networks and Learning Systems, IEEE Transactions on, vol. 32, no. 3, pp. 999-1013, March 2021, doi:
10.1109/TNNLS.2020.2979823.
Fatemifar, S., Arashloo, S.R., Awais, M., Kittler, J., ”Client-Specific Anomaly Detection for Face Presentation AttackDetection”, Pattern Recognition, Elsevier, vol. 112, 107696, 2021.
Arashloo, S.R., ”Unseen Face Presentation Attack Detection Using Sparse One-Class Multiple Kernel FusionRegression”, Circuits and Systems for Video Technology, IEEE Transactions on, doi: 10.1109/TCSVT.2020.3046505,2020.
Arashloo, S.R., ”`p -Norm Multiple Kernel One-Class Fisher Null-Space”, under review.
Arashloo, S.R., ”Mixed (r, p)-Norm One-Class Multiple Kernel Fisher Null-Space”, in preparation.
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