Fingerprint Image Enhancement Using Fourier Domain Analysis

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Fingerprint Image EnhancementUsing Fourier
Domain Analysis

• Sharat Chikkerur
• ssc5_at_cedar.buffalo.edu

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Organization

• Background on Biometrics
• Introduction to Fingerprints
• Fingerprint Image Enhancement
• Introduction to Fourier Analysis
• What are Contextual Filters
• Enhancement Algorithm
• Enhancement Results

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Biometrics

• Definition
• Biometrics is the science of verifying and
  establishing the identity of an individual
  through physiological features or behavioral
  traits.
• Examples
• Physical Biometrics
• Fingerprint
• Hand Geometry
• Iris patterns
• Behavioral Biometrics
• Handwriting
• Signature
• Speech
• Gait

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Fingerprints as biometrics

• Established Science
• Forensic institutions have used fingerprints to
  establish individual identity for over a century.
• High Universality
• Every person possesses the biometric
• High Distinctiveness
• Even identical twins have different fingerprints
  though they have the same DNA.
• High Permanence
• Fingerprints are formed in the foetal stage and
  remain structurally unchanged through out life.
• High Acceptability
• Fingerprint acquisition is non intrusive.
  Requires no training.

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Introduction to Fingerprints

• Background on Biometrics
• Introduction to Fingerprints
• Fingerprint Image Enhancement
• Introduction to Fourier Analysis
• What are Contextual Filters
• Enhancement Algorithm
• Enhancement Results

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Fingerprint Features
Fingerprints can be classified based on the ridge
flow pattern
Fingerprints can be distinguished based on the
ridge characteristics
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Fingerprint Verification System

• Research at CUBS Includes
• Fingerprint Image Enhancement
• Minutiae Feature Extraction
• Point pattern matching

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Fingerprint Image Enhancement

• Background on Biometrics
• Introduction to Fingerprints
• Fingerprint Image Enhancement
• Introduction to Fourier Analysis
• What are Contextual Filters
• Enhancement Algorithm
• Enhancement Results

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Why do we need enhancement?
High contrast print
Typical dry print
Faint print
Low contrast print
Typical Wet Print
Creases
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Need for Enhancement
Original Print
Extracted Features
Ground Truth
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Traditional Approach
Local Orientation ?(x,y) Gradient Method
Enhancement Frequency/Spatial
Local Ridge Spacing F(x,y) Projection Based Method
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Fourier Analysis Approach
Energy Map E(x,y)
FFT Analysis
Orientation Map O(x,y)
FFT Enhancement
Ridge Spacing Map F(x,y)
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Fourier Analysis

• Background on Biometrics
• Introduction to Fingerprints
• Fingerprint Image Enhancement
• Introduction to Fourier Analysis
• What are Contextual Filters
• Enhancement Algorithm
• Enhancement Results

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What is Fourier Analysis?

• Primarily involves interpreting the spectrum
• Provides an alternate representation of the
  signal.
• Allows us to model a system.
• Provides more information about the signal.
• Filtering and convolution become trivial.

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Interpreting the Spectrum
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Interpreting the spectrum II
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Contextual Filters

• Background on Biometrics
• Introduction to Fingerprints
• Fingerprint Image Enhancement
• Introduction to Fourier Analysis
• What are Contextual Filters
• Enhancement Algorithm
• Enhancement Results

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What are Contextual Filters?
Original Image
Frequency Domain Filter
Filtered Image
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Surface Wave Model
Fingerprint ridges can be modeled as an oriented
wave
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Validity of the model
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Enhancement Algorithm

• Background on Biometrics
• Introduction to Fingerprints
• Fingerprint Image Enhancement
• Introduction to Fourier Analysis
• What are Contextual Filters
• Enhancement Algorithm
• Enhancement Results

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Fourier Analysis Energy Map
Original Image
Energy Map
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Fourier Analysis Frequency Map
Original Image
Local Ridge Frequency Map
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Fourier Analysis-Orientation Map
Original Image
Local Ridge Orientation Map
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Enhancement Results

• Background on Biometrics
• Introduction to Fingerprints
• Fingerprint Image Enhancement
• Introduction to Fourier Analysis
• What are Contextual Filters
• Enhancement Algorithm
• Enhancement Results

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Fourier Domain Based Enhancement
Enhanced Image
Contextual Filter
Original Image
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Additional Results
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Effect on Feature Extraction
Fingerprint Image
Minutiae
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Thank You

• http//www.cubs.buffalo.edu