Camera Array System for Biometric Authentication
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Solution Overview
Problem
Biometric authentication systems face challenges in capturing high-quality images of features like eyes over a large three-dimensional field-of-view using fixed-focus cameras, as they often result in blurry images due to unknown subject distances and insufficient field of view, making it difficult to authenticate users effectively without expensive and complex adjustable-focus cameras.
Innovation Solution
The use of multiple arrays of fixed-focus cameras, each focused at different distances with partially overlapping fields of view, combined with chromatic aberration effects from varying illumination wavelengths, allows for fine-tuning the focus and selecting the best-focused image for authentication, thereby increasing the likelihood of capturing well-focused images of features like eyes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed-focus cameras are used to capture images over a large three-dimensional field-of-view, then the device complexity is reduced and cost is lowered, but the image quality deteriorates due to blur from unknown subject distances
Solution Approach 1:
The system divides the capture volume into multiple depth zones, with each camera array focused at a specific distance. By segmenting the field of view into discrete focal planes, the system maintains simple fixed-focus cameras while ensuring that at least one array captures each subject at the correct focus distance.
Solution Approach 2:
The patent adds the depth dimension to the traditional two-dimensional image plane by creating multiple arrays at different focal distances. This three-dimensional arrangement of camera arrays ensures comprehensive coverage of the capture volume, allowing subjects at any depth to be captured in focus by the appropriately focused array.
2Device complexity
If a single camera array is used, then the device complexity is minimized, but the field of view coverage is insufficient to capture subjects at various distances in focus
Solution Approach 1:
The capture volume is segmented into multiple depth regions, with each camera array responsible for a specific focal plane. This segmentation allows the system to cover a large three-dimensional field of view without requiring each individual camera to have an excessively wide angle that would compromise image quality.
Solution Approach 2:
Multiple camera arrays are merged to form a unified capture system. Each array contributes its focused view to the overall coverage, and the system combines their capabilities to achieve comprehensive three-dimensional field of view coverage while maintaining simple fixed-focus cameras throughout.
3Manufacturing precision
If adjustable-focus cameras are used to maintain image quality across varying distances, then image focus quality is improved, but the device complexity and cost increase significantly
Solution Approach 1:
Instead of making the cameras adjustable to match the subject distance, the patent inverts the approach by making the subject effectively match the camera's fixed focus distance. Multiple fixed-focus arrays at different distances ensure that whichever fixed focal plane the subject falls on, that array will capture it in focus.
Solution Approach 2:
The system uses multiple copies of simple fixed-focus camera arrays rather than one complex adjustable-focus camera. Each copy is identical and focused at a different distance, creating redundant capture capability across depth without requiring any individual camera to be complex.
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
This approach enables the capture of high-quality images across a large three-dimensional field-of-view, improving the reliability and usability of biometric authentication systems, particularly in applications where complex cameras are not feasible, by leveraging chromatic aberration to select the best-focused image for further processing.
Implementation Method 1
capturing, using a first array of multiple image acquisition devices, a first set of images of a scene
Implementation Method 2
One or more illumination sources can be used for illuminating with electromagnetic radiation of a first wavelength range during a first time period, and with electromagnetic radiation of a second wavelength range during a second time period
Data Source
AI summary
The technology described herein can be embodied in a method that includes capturing, using a first array of multiple image acquisition devices, a first set of images of a scene, and capturing, using a second array of multiple image acquisition devices, a second set of images of the scene. The devices of the first array are each focused at a first distance, and the devices of the second array are each focused at a second distance. The method also includes identifying a first image and a second image in the first and second sets of images, respectively, to include a feature of interest. The method further includes determining a focal score for each of the first and second images, selecting one of the images based on a comparison of the corresponding focal scores, and initiating an authentication process based on the selected image.