Pupil Tracking System for Impairment Detection Under Ocular Occlusion
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Solution Overview
Problem
Current systems fail to accurately and automatically track the size, location, and movement of a subject's pupil, especially under conditions like light specularities, heavy eye makeup, or bushy eyebrows, leading to unreliable impairment detection in workplace settings.
Innovation Solution
A pupil tracking system using digital image frames processed with region-growing and morphological filtering to extract and track pupil centroids, compensating for specularities and detecting blinks, ensuring accurate pupil area and location measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pupil detection methods (darkest area thresholding or ellipse fitting) are used, then the system can process images quickly, but the measurement accuracy deteriorates when light specularities, heavy eye makeup, or bushy eyebrows occlude the pupil
Solution Approach 1:
The patent segments the pupil detection process into multiple stages: initial seed point identification, region growing phase, and boundary refinement phase. This segmentation allows the system to handle occluding conditions by progressively refining the pupil boundary rather than relying on a single global threshold or fit, thereby improving measurement accuracy under various occlusion conditions.
Solution Approach 2:
The patent applies local quality by using adaptive thresholding and region growing that adjusts to local image characteristics rather than applying a global threshold. The algorithm identifies seed points based on local intensity minima and grows regions based on local gradient information, allowing accurate pupil detection even when parts of the image contain occluding elements like makeup or eyebrows.
2Productivity
If automated pupil tracking is implemented, then productivity increases by enabling rapid impairment screening, but reliability decreases due to failures under complex lighting and occlusion conditions
Solution Approach 1:
The patent implements feedback mechanisms where the region growing algorithm continuously refines the pupil boundary based on accumulated evidence from previous iterations. The system uses feedback from gradient calculations and intensity comparisons to adjust the growing region, ensuring reliable detection even under challenging conditions while maintaining high processing speed through efficient algorithm design.
Solution Approach 2:
The patent performs preliminary actions by identifying seed points and pre-processing the image to highlight pupil-specific features before the main detection algorithm runs. This preliminary processing prepares the data structure to facilitate rapid and reliable pupil detection during the actual measurement phase, enabling both high productivity and reliability.
3Device complexity
If ellipse fitting is used to detect pupils, then the device complexity is reduced, but measurement precision deteriorates when the pupil has a non-circular shape due to occlusions
Solution Approach 1:
The patent employs dynamic boundary following rather than static ellipse fitting. The region growing algorithm dynamically adapts to the actual pupil shape by following intensity gradients and boundary features, allowing the detected pupil contour to change shape according to actual anatomical features and occlusion patterns, thereby maintaining measurement precision without excessive complexity.
Data Source
AI summary
The present system for analyzing eye responses accurately and automatically tracks the size, location, and movement of a subject's pupil(s) in response to a predetermined test protocol. These eye responses include both ocularmotor and pupillary responses to illumination and target tracking for either eye or both eyes simultaneously. The series of digital image frames of a subject's eyes, taken during the execution of a predetermined stimulus protocol, are automatically processed to determine pupil location, size, and responsiveness to changes in illumination.