Compact Iris Recognition Using Angularly Differentiated Imaging
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Solution Overview
Problem
Conventional iris recognition systems face challenges in maintaining accurate biometric performance while being compact enough for small device designs, as they struggle with infrared-eye effects that reduce contrast between the pupil and iris, making it difficult to delineate the iris-pupil boundary, especially when the camera-illuminator spacing is less than a tenth of the distance between the camera and the subject.
Innovation Solution
The iris recognition system exploits the angular dependence of pupil shade by capturing at least two angularly differentiated iris images, using differential contrast to accurately delineate the iris-pupil boundary even when the spacing between the illuminator and camera is less than a tenth of the distance, allowing for compact device design and operation without suppressing infrared-eye effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the infrared illuminator is placed close to the infrared camera to achieve compact device design, then the device size is reduced and ease-of-use is improved, but the angle between the illumination line and camera line becomes too small causing red-eye effect that reduces pupil-iris contrast and makes boundary delineation difficult
Solution Approach 1:
The patent segments the imaging process by capturing multiple images at different illumination angles. Instead of relying on a single image where the pupil-iris boundary may be indistinct due to red-eye, the system divides the problem into multiple angular views, allowing the boundary to be identified through comparison across segmented images where at least one provides sufficient contrast.
Solution Approach 2:
The patent adds the angular dimension to the imaging process. By varying the angle between the illuminator and camera relative to the subject's eye, the system transforms a two-dimensional imaging problem into a three-dimensional solution space, where multiple angular perspectives provide the information needed to overcome the red-eye effect and accurately delineate boundaries in a compact device configuration.
2Measurement precision
If the angle between the illuminator and camera is increased to suppress red-eye and improve pupil-iris contrast, then measurement precision is improved, but the device size increases and ease-of-use deteriorates
Solution Approach 1:
The patent makes the illumination angle dynamic rather than fixed. The system varies the angle between the illuminator and camera during the imaging process, capturing images at multiple angular positions. This dynamic approach allows the device to achieve accurate boundary delineation through angular variation without requiring a permanently large separation between components, thus maintaining compact device size while improving measurement precision.
Solution Approach 2:
The patent employs periodic action by sequentially capturing images at different illumination angles. The illuminator and camera are positioned at varying angles in a systematic sequence, allowing the system to gather information from multiple perspectives over time. This periodic angular variation enables accurate pupil-iris boundary detection without requiring constant large component separation, thus avoiding increased device volume.
3Reliability
If conventional iris recognition algorithms are used that expect dark pupils, then biometric performance is maintained, but the device must be large enough to ensure proper illuminator-camera spacing to prevent red-eye
Solution Approach 1:
The patent changes the parameter of illumination angle rather than relying on fixed component spacing. By varying the angular parameter between illuminator and camera, the system can achieve the necessary pupil-iris contrast for accurate biometric recognition without requiring large physical separation between components. This parameter change allows compact device design while maintaining reliability through multiple angular perspectives that ensure at least one image provides sufficient contrast for conventional algorithms.
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 accurate iris recognition and segmentation in small devices, allowing for compact placement and operation in restricted spaces, such as on laptops or door jambs, without the need for large device sizes, thus balancing biometric performance and ease-of-use.
Implementation Method 1
an infrared illuminator (NIRL) and an infrared camera (NIRC)
Implementation Method 2
Light leaving an illuminator and entering a subject's pupil travels along a first line. Light scattered from the eye tissue behind the pupil returns from the subject to a camera along a second line.
Data Source
AI summary
Disclosed herein are methods, apparatus, and systems for iris recognition. A method includes acquiring at least two angularly differentiated iris images from a subject needing access, processing each of the at least two angularly differentiated iris images to generate at least one boundary delineated image from one of the at least two angularly differentiated iris images, applying image comparative analysis to the at least two angularly differentiated iris images to generate a boundary delineated image when the processing fails to produce the at least one boundary delineated image, segmenting and encoding one of the at least one boundary delineated image or the boundary delineated image to generate at least one iris template, matching the at least one iris template against an enrolled iris, and accepting the subject for access processing when the at least one iris template matches the enrolled iris.