Single Sensor Biometric Capture with Dynamic Illumination
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Solution Overview
Problem
Biometric recognition systems, particularly those using facial and iris recognition, face challenges such as registration errors, pose variations, insufficient sensor dynamic range, and illumination issues, leading to false positives and negatives when attempting to identify individuals using a single sensor.
Innovation Solution
A method and system that capture high-quality images of both iris and face using a single sensor by varying camera and illumination settings between acquisitions, allowing for optimal image acquisition parameters for each biometric recognition step, including adjusting settings like illumination power, integration time, and wavelengths within a short time frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sensor is used to capture both face and iris images with constant settings, then device complexity is reduced, but measurement precision deteriorates because the sensor cannot simultaneously capture both biometrics within its dynamic range
Solution Approach 1:
The patent applies dynamics by making the sensor settings adjustable and changeable over time. The system dynamically modifies illumination intensity, exposure time, and gain settings between capturing face images and iris images, allowing optimal settings for each biometric type while using a single sensor.
Solution Approach 2:
The patent changes sensor parameters (illumination intensity, exposure time, gain) to match the specific requirements of each biometric type. Face images are captured with one set of parameters while iris images are captured with different parameters optimized for iris reflectance characteristics, resolving the dynamic range conflict.
2Measurement precision
If different illumination settings are used for face and iris capture, then measurement precision improves, but device complexity increases due to multiple sensors or complex switching mechanisms
Solution Approach 1:
The patent makes a single sensor universal by enabling it to perform both face capture and iris capture functions. The sensor is configured with adjustable parameters that allow it to adapt to the different illumination and exposure requirements of each biometric type, eliminating the need for separate dedicated sensors.
Solution Approach 2:
The system dynamically switches between different operational modes for the single sensor, adjusting illumination intensity and exposure settings based on whether capturing face or iris data, thereby achieving multi-functionality without multiple physical sensors.
3Loss of time
If images are captured simultaneously with fixed settings, then acquisition time is reduced, but measurement precision deteriorates due to inability to optimize for each biometric type
Solution Approach 1:
The patent uses periodic action by rapidly alternating between capturing face images and iris images in sequence. The system performs multiple quick captures in succession with different optimized settings for each biometric type, minimizing total acquisition time while maintaining precision through repeated measurements.
4Measurement precision
If sensor dynamic range is increased to capture both face and iris, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
Instead of increasing sensor dynamic range hardware specifications, the patent changes operational parameters (illumination intensity, exposure time, gain) to match the requirements of each biometric type. This software-based parameter adjustment achieves the effect of extended dynamic range without hardware complexity.
Data Source
AI summary
High quality, sharply focused images of an iris and the face of a person are acquired in rapid succession in either sequence by a single sensor and one or more illuminators, preferably within less than one second of each other, by changing the sensor settings or illumination levels between each acquisition.