Pupil Detection Using Cornea Reflection as Reference
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Solution Overview
Problem
Conventional pupil detection methods struggle when the cornea-reflected image overlaps the pupil, especially in low-resolution images or when it is difficult to adjust the floodlight position, leading to increased 'hidden areas' and reduced detection accuracy.
Innovation Solution
A pupil detection device and method that utilize line segments with a reference point of the cornea-reflected image to calculate luminance evaluation values, specifying a pupil center straight line based on these values, and detecting the pupil image based on the luminance state around this line, even when most of the pupil is hidden by the cornea-reflected image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a floodlight is used to secure illuminance in low-light conditions, then the illuminance is sufficient for detection, but a cornea-reflected image is generated that may overlap and hide the pupil image
Solution Approach 1:
The detection process is segmented into multiple stages: first detecting the cornea-reflected image position, then using it as a reference to search for the pupil image in specific directions. This segmentation allows the system to handle the overlapping issue by treating the cornea-reflected image not as interference but as a useful reference marker.
Solution Approach 2:
The cornea-reflected image, which was previously considered a harmful factor hiding the pupil, is converted into a beneficial reference point. The invention uses the position and orientation of the cornea-reflected image to determine the search direction and starting point for pupil detection, thereby turning the interference into a useful cue.
2Reliability
If the position of the floodlight is changed to avoid cornea-reflected image overlap, then pupil detection can be performed, but it becomes difficult when multiple floodlights are used or when floodlight position cannot be adjusted
Solution Approach 1:
Instead of trying to avoid the cornea-reflected image by adjusting floodlight position, the invention inverts the approach by using the cornea-reflected image itself as the reference point for detection. The pupil search is performed relative to the cornea-reflected image position, making the detection robust regardless of floodlight configuration.
Solution Approach 2:
The system uses the cornea-reflected image, which is automatically generated by the floodlight, as a self-provided reference marker for pupil detection. This eliminates the need for external adjustment of floodlight positions or additional reference objects, as the system itself generates the reference it needs.
3Reliability
If the physical size of the cornea-reflected image is reduced, then the hidden area of the pupil is reduced, but in low-resolution images the cornea-reflected image still occupies significant area relative to the pupil
Solution Approach 1:
The invention changes the detection parameters from trying to minimize the cornea-reflected image size to using its position and orientation as detection cues. By changing from a size-based approach to a position-based approach, the system becomes independent of the cornea-reflected image size, making it suitable for low-resolution images.
4Measurement precision
If conventional pupil detection methods are used assuming complete visibility of the pupil image, then detection is accurate when the pupil is fully visible, but detection fails when the pupil is partially hidden by the cornea-reflected image
Solution Approach 1:
The cornea-reflected image serves as an intermediary marker that mediates the detection process. Instead of directly detecting the pupil without references, the system uses the cornea-reflected image as an intermediate reference point to guide the pupil search, enabling detection even when the pupil is partially obscured.
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 allows for stable pupil detection by actively using cornea-reflected image information, improving detection accuracy even when the pupil is largely obscured.
Implementation Method 1
a cornea-reflected image generated as floodlight is projected on a cornea of an eyeball is observed on the eyeball
Data Source
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AI summary
A pupil detection device and a pupil detection method, which are capable of stably detecting the pupil by actively using information of cornea-reflected image even when most of the pupil is hidden by the cornea-reflected image. In pupil detection device (100), peripheral state evaluating section (105) sets a plurality of line segments having a reference point of a cornea-reflected image as one end and having a predetermined length, and calculates a luminance evaluation value based on luminance of each pixel in each line segment and reference luminance. Pupil center straight line calculation section (106) specifies a pupil center straight line passing through a center of a pupil image from among a plurality of line segments based on a luminance evaluation value. Pupil search section (107) detects a pupil image based on a luminance state around the pupil center straight line.