Biometric Scanner Illumination Switching for Presentation Attack Detection
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Solution Overview
Problem
The increasing use of biometrics for asset security has led to a heightened threat of presentation attacks, where individuals attempt to circumvent biometric security measures using fabricated or fake biometric presentations.
Innovation Solution
An access control system (ACS) that incorporates a scanning apparatus with an illumination system capable of switching between non-patterned and patterned light modes, using liquid crystals to achieve this switching and enhance biometric identification and presentation attack detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate illumination systems are used for uniform and patterned light, then each illumination mode can be optimized for its specific function, but the device complexity increases
Solution Approach 1:
The patent combines separate illumination systems into a single integrated illumination module that can produce both uniform and patterned light. The illumination module includes a light source and a liquid crystal display (LCD) panel that can be electronically controlled to switch between different illumination patterns, eliminating the need for multiple separate illumination systems while maintaining the functional advantages of each mode
Solution Approach 2:
The illumination system is made dynamic through the use of an electronically controllable LCD panel that can switch between uniform and patterned illumination modes based on operational requirements. This dynamic reconfiguration allows the system to adapt to different biometric scanning needs without requiring physical reassembly or multiple fixed illumination systems
2Measurement precision
If uniform illumination is used for biometric capture, then the entire biometric presentation is evenly lit for comprehensive scanning, but presentation attack detection capability is reduced
Solution Approach 1:
The system employs periodic switching between uniform illumination mode for comprehensive biometric capture and patterned illumination mode for presentation attack detection. The illumination pattern changes sequentially to first provide uniform lighting for complete finger/face/iris illumination, then switches to patterned lighting to create specific illumination zones that reveal characteristics of live versus fake presentations
Solution Approach 2:
The patterned illumination mode applies local quality by creating specific illumination zones at different locations on the biometric presentation surface. This allows certain areas to be illuminated while other areas remain in shadow, creating contrast that highlights the three-dimensional structure and surface characteristics of the presentation, making it easier to distinguish live from fake presentations
3Reliability
If patterned light is used for presentation attack detection, then the ability to detect fake presentations is enhanced, but the overall biometric scanning capability is compromised
Solution Approach 1:
The system alternates between uniform and patterned illumination modes in a sequential manner. During uniform illumination phase, the entire biometric presentation is evenly lit for comprehensive feature capture. During patterned illumination phase, specific zones are illuminated to enable presentation attack detection. This periodic switching ensures both biometric scanning and PAD capabilities are maintained without compromise
Solution Approach 2:
The illumination system maintains continuous operational utility by seamlessly transitioning between uniform and patterned illumination modes. Both illumination types are available and can be activated as needed, ensuring the system continuously provides useful functionality for either biometric identification or presentation attack detection without requiring system reconfiguration or losing operational capability
4Reliability
If multiple separate illumination systems are implemented, then each illumination mode can be optimized, but specular reflection issues increase
Solution Approach 1:
The patent merges multiple illumination systems into a single integrated module with a unified light source and LCD panel. This consolidation reduces the number of separate optical paths and light sources that could generate specular reflections, while still providing both uniform and patterned illumination capabilities through electronic control of the LCD panel
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The ACS effectively captures biometric presentations with uniform and patterned illumination, improving identification accuracy and enhancing the detection of presentation attacks, while also simplifying the illumination system and reducing the risk of specular reflection issues.
Implementation Method 1
By incorporating a sheet of randomly oriented liquid crystal ("LC") material that aligns upon application of an electric field across the LC sheet, the sheet can transition from anywhere between diffuse to clear, thereby changing the illumination at the platen from non-patterned to a patterned distribution
Data Source
AI summary
An access control system (ACS) and method controls access to a secure asset. The ACS includes a light emitting unit configured to emit light, an electronically addressable element configured to be electronically switched between a first optical state and a second optical state, an optical sensor configured to sense light, and a controller. The controller is configured to cause the electronically addressable element to switch between a first optical state, which produces non-patterned light at an illumination target, and a second optical state, which produces patterned light at the illumination target, receive, from the optical sensor, data indicative of light reflected from a presentation illuminated at the illumination target, and determine access to a secure asset based on the data indicative of light reflected from the presentation.