Rotating Mirror Face Capture for Distortion-Free Biometrics
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Solution Overview
Problem
Existing biometric facial recognition systems face challenges in capturing high-quality images that are free from imaging errors, particularly in varying lighting conditions and for individuals of different heights, leading to false rejections and increased manual verification needs.
Innovation Solution
A device with a rotating optical mirror and evaluation unit that adjusts the beam path to align perpendicular to the face, combined with an overview camera for depth information, and deception detection sensors, ensures distortion-free imaging and shadow-free illumination for individuals of varying heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If automatic passport photo machines are used, then productivity increases, but image quality deteriorates due to imaging errors and incorrect user posture
Solution Approach 1:
The patent implements dynamic adjustment mechanisms including a rotation device that adjusts the optical mirror angle based on detected face position, and illumination devices that adapt to varying lighting conditions. This allows the system to maintain high image quality while processing multiple users automatically, resolving the contradiction between productivity and image quality.
Solution Approach 2:
The system incorporates feedback loops where the detection unit continuously monitors face position and the control unit adjusts the optical mirror and illumination accordingly. This real-time feedback ensures that imaging errors are corrected dynamically, maintaining passport photo quality standards while preserving automated processing efficiency.
2Device complexity
If the optical mirror is fixed, then device complexity is reduced, but adaptability deteriorates for users of varying sizes and postures
Solution Approach 1:
The patent introduces a rotation device that enables dynamic adjustment of the optical mirror's angular position. This single degree of freedom adjustment allows the system to accommodate users of different heights and postures without requiring complex multi-axis mechanisms, thus maintaining relatively simple device architecture while significantly improving adaptability.
Solution Approach 2:
The rotatable optical mirror serves multiple functions: it adjusts for different user heights, compensates for posture variations, and maintains proper optical alignment across diverse user scenarios. This multi-functionality allows a single simple mechanism to address multiple adaptability requirements simultaneously.
3Manufacturing precision
If image processing software is used to correct distortions, then manufacturing precision improves, but loss of information increases due to prohibited post-processing
Solution Approach 1:
The patent implements preliminary action by using the rotatable optical mirror to pre-align the optical path and minimize trapezoidal distortion before image capture. The illumination devices are also pre-positioned to provide shadow-free lighting from the correct angles. This prevents imaging errors at the source rather than requiring post-processing correction, thus maintaining image integrity while achieving high precision.
Solution Approach 2:
The patent replaces software-based image correction with a mechanical solution - the rotatable optical mirror physically adjusts the optical path to capture undistorted images directly. This mechanical substitution eliminates the need for information-lossy post-processing while maintaining or improving image accuracy.
4Ease of operation
If the beam path is not perpendicular to the face, then ease of operation improves for various postures, but measurement precision deteriorates due to trapezoidal distortion
Solution Approach 1:
The rotation device dynamically adjusts the optical mirror's angle based on the detected face position, ensuring that the beam path becomes perpendicular to the face regardless of the user's initial posture or height. This dynamic alignment maintains measurement precision while allowing operation with various user postures.
Solution Approach 2:
The system changes the optical parameters by rotating the mirror to alter the beam path angle. This parameter adjustment ensures perpendicular incidence on the face, eliminating trapezoidal distortion and maintaining facial feature measurement accuracy while accommodating diverse user positions.
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 device captures high-quality, distortion-free facial images compliant with ISO 19794-5 standards, minimizing mechanical complexity and enabling efficient operation for individuals of varying sizes, while reducing false rejections and enhancing security.
Implementation Method 1
an optical mirror (104) for folding a beam path (105) running between the face (110) of the person and the camera (103)
Implementation Method 2
sensor (120) for detecting fraud, in particular in the form of a thermal imaging camera (121) for recording a thermal image of a facial area (110) of the person, with the evaluation and/or control unit (108) being designed to detect local thermal inhomogeneity
Data Source
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AI summary
The invention relates to a device (100) for capturing biometric features of a person's face (110), comprising a housing (101) in which a camera (103) having a first focal length for capturing the biometric features and an optical mirror (104) for folding a beam path (105) running between the person's face (110) and the camera (103) are arranged, and comprising an evaluation and/or control unit (108) which is configured to be in communication connection with the camera (103). The evaluation and/or control unit (108) is configured to cause a rotation device (144) located in the housing (101) to rotate the optical mirror (104) depending on a detected position of the person's face (110) such that the beam path (105) strikes a straight line (146) perpendicular to or parallel to a point on the face (110) running from the chin to a point between the eyes.The invention also relates to a method for recording biometric characteristics.