Biometric Authentication Device Distance Correction Mechanism
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Solution Overview
Problem
Existing biometric authentication systems face challenges in achieving high-accuracy authentication due to variations in image focus caused by differences in subject distance and individual facial features.
Innovation Solution
The biometric authentication device employs a correction mechanism that utilizes difference distance information to correct deviations between estimated and focal distances, enabling precise focal point control and selection of in-focus images for authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If distance estimation is performed based on feature point distances in images, then authentication can be performed without additional distance sensors, but deviation between estimated distance and actual focal distance reduces image focus accuracy
Solution Approach 1:
The system uses in-focus information as feedback to correct the estimated distance. The correction unit adjusts the estimated distance based on whether the image is in focus, creating a closed-loop system that improves distance accuracy without requiring additional sensors.
Solution Approach 2:
The patent replaces mechanical distance sensors with an optical-based correction mechanism using in-focus information from the imaging system itself, substituting a complex mechanical measurement system with a simpler optical feedback system.
2Speed
If focal point control is performed based on uncorrected estimated distance, then image acquisition can be performed quickly, but image focus quality deteriorates due to distance deviation
Solution Approach 1:
The system performs preliminary distance estimation using feature points before image acquisition, then refines this estimation using in-focus information. This preliminary action allows the system to prepare focal point control settings in advance while maintaining accuracy through subsequent correction.
Solution Approach 2:
The correction unit acts as an intermediary between the estimated distance and the focal point control. It processes the estimated distance through in-focus information to produce a corrected distance value, mediating between speed and accuracy requirements.
3Reliability
If multiple images are captured to ensure in-focus quality, then authentication accuracy improves, but processing time and complexity increase
Solution Approach 1:
The in-focus determination unit provides immediate feedback on image focus quality, allowing the system to make real-time decisions about whether additional images are needed. This feedback mechanism reduces the need for multiple trial images by enabling precise focal point control.
Solution Approach 2:
The imaging system uses its own in-focus information to correct distance estimates and control focal points, making the system self-correcting without requiring external intervention or multiple redundant images. The system serves itself by using its output (in-focus information) to improve its input (distance estimation).
Data Source
AI summary
A biometric authentication device, by utilizing difference distance information obtained on the basis of in-focus information indicating the degree of focusing in an image of a subject serving as the target of biometric authentication and an estimated distance to the subject obtained from the distance between feature points in the image, generates a corrected distance in which a deviation between the estimated distance and a focal distance to the subject has been corrected on the basis of the difference distance information. The biometric authentication device generates information for controlling a focal point during image acquisition of the subject on the basis of the corrected distance, and generates information for selecting an image to be biometrically authenticated from among images of the subject photographed after controlling the focal point.