Coded Illumination Imaging for Biometric Accuracy
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Solution Overview
Problem
Biometric identification systems face accuracy and efficiency issues due to the adverse effects of ambient lighting conditions on captured images, which can lead to false positives and false negatives, especially in uncontrolled illumination environments.
Innovation Solution
The use of spatially separated illumination sources emitting electromagnetic radiation at multiple non-overlapping wavelength ranges, allowing for the generation of images that enhance the effects of controlled illumination over ambient light sources, thereby reducing ambient lighting impacts through coded-light sequences and photometric stereo processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single illumination source is used, then device complexity is low, but image quality and biometric identification accuracy deteriorate under ambient lighting conditions
Solution Approach 1:
The illumination system is segmented into multiple spatially separated illumination sources, each emitting electromagnetic radiation in different non-overlapping wavelength ranges. This segmentation allows the system to capture images under multiple coded illumination patterns simultaneously, enhancing the ability to distinguish controlled illumination from ambient light, thereby improving biometric identification accuracy without requiring a single complex illumination system.
Solution Approach 2:
The patent introduces a spectral dimension by using illumination sources that emit in different non-overlapping wavelength ranges (e.g., visible light, infrared). This adds a wavelength dimension to the illumination approach, allowing the system to differentiate between controlled illumination and ambient light based on spectral characteristics, thus improving measurement precision while maintaining manageable device complexity.
2Reliability
If multiple spatially separated illumination sources with non-overlapping wavelength ranges are used, then ambient lighting effects are reduced, but device complexity increases
Solution Approach 1:
The system segments both the illumination sources and sensors into multiple independent units, each handling specific wavelength ranges. Multiple illumination sources emit in non-overlapping wavelength ranges, and corresponding sensors are tuned to detect these specific ranges. This segmentation enables the system to reliably capture images under ambient lighting by isolating controlled illumination signals from ambient light through spectral separation.
Solution Approach 2:
The patent changes the wavelength parameter of illumination sources to non-overlapping ranges (e.g., visible, infrared) and corresponds this with sensors having matching spectral sensitivity. By varying the wavelength parameter across multiple illumination-sensor pairs, the system achieves reliable image capture under ambient lighting conditions while managing device complexity through standardized component design.
3Measurement precision
If coded illumination sequences are applied, then ambient light influence is reduced, but processing complexity increases
Solution Approach 1:
The system applies coded illumination sequences using periodic modulation patterns (e.g., temporal coding, frequency modulation) to the multiple illumination sources. These periodic patterns allow the processing system to distinguish controlled illumination from ambient light through correlation techniques, improving the signal-to-ambient-light ratio while keeping processing complexity manageable through efficient signal processing algorithms.
Solution Approach 2:
The system uses feedback from the captured images to adjust and optimize the coded illumination sequences. By analyzing the received signals and comparing them against expected patterns from the coded illumination, the system can refine its processing algorithms and adapt to varying ambient lighting conditions, improving measurement precision without requiring excessively complex processing systems.
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 images that are substantially independent of ambient lighting, improving the accuracy and efficiency of biometric identification systems by reducing the influence of ambient illumination and allowing for the detection of features otherwise undetectable, such as micro-features in the eye or face.
Implementation Method 1
a first illumination source radiating electromagnetic radiation in a first wavelength range, and receiving, from a second sensor, during the first time period, information representing reflected light received from the target, wherein the target is illuminated by a second illumination source radiating electromagnetic radiation in a second wavelength range
Implementation Method 2
information representing reflected light received from the target
Data Source
AI summary
The technology described in this document can be embodied in a method that includes receiving during a first time period, information from a first sensor representing a target illuminated by a first illumination source radiating in a first wavelength range, and information from a second sensor representing the target illuminated by a second illumination source radiating in a second wavelength range. The method also includes receiving during a second time period, information from the first sensor representing the target illuminated by the second illumination source radiating in the first wavelength range, and information from the second sensor representing reflected light received from the target illuminated by the first illumination source radiating in the second wavelength range. The method also includes generating a representation of the image in which effects due to the first and second illumination sources are enhanced over effects due to ambient light sources.