Biometric Image Output Control for Face Authentication Distance
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Solution Overview
Problem
Face authentication devices face challenges in maintaining recognition performance due to variations in subject distance, leading to optical blurring and reduced recognition accuracy, while increasing lighting can cause inconvenience and motion blurring.
Innovation Solution
A biometric image output control method that adapts the size, focal point, and brightness of the biometric image based on the distance from the camera to the subject, ensuring the imaging environment meets a predetermined recognition condition, allowing users to easily adjust their position for optimal authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aperture value is increased to increase the depth of field, then optical blurring is reduced, but the amount of light accumulated per unit time decreases making the face image darker
Solution Approach 1:
The patent dynamically adjusts camera parameters including aperture value, exposure time, and gain based on the measured distance to the user. When the user is within the depth of field range, the system maintains optimal aperture for depth of field while compensating brightness through exposure time and gain adjustments, ensuring both sharp focus and adequate image brightness for recognition.
2Illumination intensity
If the exposure time is increased to brighten the face image, then illumination is improved, but motion blurring is generated due to user movement
Solution Approach 1:
The system dynamically determines exposure time based on real-time distance measurement and user position relative to the depth of field range. When the user is within the optimal range, exposure time is set to achieve proper brightness without excessive duration that would cause motion blur. The system continuously adapts these parameters as the user moves.
3Illumination intensity
If the number of lightings is increased to improve face image brightness, then illumination is enhanced, but the size of the face recognition device increases
Solution Approach 1:
Instead of adding more lighting fixtures, the patent optimizes the utilization of existing lighting by dynamically adjusting camera parameters (aperture, exposure time, gain) based on user distance. This approach achieves adequate image brightness without requiring additional lighting hardware, thereby avoiding increased device size.
4Illumination intensity
If a strong lighting is used to brighten the face image, then illumination is improved, but the eyes of the user are adversely affected causing inconvenience
Solution Approach 1:
The system achieves adequate face image brightness through camera parameter optimization (exposure time, gain, aperture) rather than increasing lighting intensity. This approach maintains proper illumination for recognition while avoiding the harmful effects of strong lighting on the user's eyes.
Data Source
AI summary
A biometric image output control method in a biometric authentication device comprises the step of generating a biometric image by imaging an living body to be authenticated; determining whether an imaging environment; if the imaging environment satisfies a predetermined recognition condition, controlling a change rate of a size of a biometric image, a change rate of a focal point of the biometric image and a change rate of a brightness of the biometric image according to a distance to the living body to be authenticated; and if the imaging environment does not satisfy the predetermined recognition condition, overly controlling at least one of the change rate of the size of the biometric image, the change rate of the focal point of the biometric image and the change rate of the brightness of the biometric image according to the distance.