Liquid-Crystal Lens Modulates Light Intensity for Off-Center Face Detection
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Solution Overview
Problem
Conventional face detection systems using 2D face recognition are prone to failure due to varying light intensity caused by lens characteristics, particularly when the face is positioned off-center, as light intensity decreases with distance from the lens center.
Innovation Solution
A structured-light face detection system that includes a projector, a liquid-crystal lens, and an image capture device, where the liquid-crystal lens modulates light to shape the transmitted light, alternating it with the original light to compensate for varying intensity, resulting in an integrated image with homogeneous light intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional 2D face recognition is used, then the system is simple to implement, but detection accuracy deteriorates due to varying light intensity from lens characteristics
Solution Approach 1:
The patent applies local quality by making different regions of the projected light pattern have different intensities. Specifically, the light pattern is designed with higher intensity at the periphery and lower intensity at the center, which compensates for the lens's natural tendency to concentrate light at the center. This local variation in light intensity ensures uniform illumination across the entire detection field, thereby maintaining face detection accuracy for off-center positions without increasing overall system complexity.
2Adaptability or versatility
If the face is positioned off-center, then the system has flexibility in positioning, but light intensity decreases causing detection failure
Solution Approach 1:
The patent makes different parts of the light distribution have different intensities tailored to the specific detection position. When detecting off-center faces, the system adjusts the light pattern to concentrate intensity in the region where the face is located, rather than using uniform illumination. This localized intensity adjustment ensures that faces at various positions receive adequate lighting for accurate detection.
Solution Approach 2:
The patent employs dynamic adjustment of the light pattern intensity distribution based on the detected face position. The system can adaptively modify the illumination characteristics in real-time, switching between different intensity patterns to optimize detection conditions for faces at various locations within the field of view, thereby maintaining both positioning flexibility and sufficient illumination intensity.
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 solution ensures accurate face detection by maintaining consistent light intensity across the image, enabling correct detection even when the face is positioned off-center, as demonstrated by the integration of original and shaped light images captured by the image capture device.
Implementation Method 1
The liquid-crystal lens controllably modulates liquid-crystal molecules thereof to shape the original transmitted light
Implementation Method 2
shape the original transmitted light, thereby generating a shaped transmitted light
Implementation Method 3
captures an image from a reflected light from the scene
Data Source
AI summary
An object detection system includes a projector that projects an original transmitted light on a scene containing an object; an adjustable device configured to shape the original transmitted light, thereby generating a shaped transmitted light; and an image capture device configured to capture an image from a reflected light from the scene. The original transmitted light is alternated with the shaped transmitted light, thereby resulting in an integrated image captured by the image capture device.