Ophthalmologic Apparatus Eye Tracking Phase-Only Correlation
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Solution Overview
Problem
Current ophthalmologic apparatuses face challenges in achieving high-precision tracking of eye movements during anterior segment imaging, particularly due to the presence of static features like eyelids and eyelashes, which hinder accurate phase-only correlation processing.
Innovation Solution
An ophthalmologic apparatus that includes an optical system, an image acquiring unit for capturing anterior segment images at different times, a rotational movement calculator, a registration unit for aligning partial images based on calculated movement amounts, and a movement mechanism controlled by a controller to adjust for both rotational and parallel movements, allowing for precise tracking by specifying suitable partial images for phase-only correlation processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-only correlation processing is performed on the entire anterior segment image, then tracking can be performed, but the presence of static features like eyelids and eyelashes causes inaccurate misregistration calculation
Solution Approach 1:
The anterior segment image is divided into multiple partial images, and phase-only correlation processing is performed separately on each partial image. This segmentation allows the system to exclude regions containing static features (eyelids, eyelashes) from the calculation, thereby improving tracking accuracy by using only dynamic regions that accurately reflect eye movement.
Solution Approach 2:
The invention extracts and excludes static features (eyelids, eyelashes) from the image processing by performing phase-only correlation on partial images that contain only dynamic regions. This extraction of problematic elements prevents them from interfering with the misregistration calculation, resolving the contradiction between performing tracking and maintaining accuracy.
2Measurement precision
If the optical system is adjusted frequently to maintain alignment, then tracking precision is improved, but the complexity of the movement mechanism increases
Solution Approach 1:
The system performs phase-only correlation processing to calculate misregistration amounts between consecutive images, and uses this feedback information to control the movement mechanism for adjusting alignment. This closed-loop feedback approach maintains high alignment accuracy while optimizing the frequency and magnitude of adjustments, thereby managing mechanism complexity.
Solution Approach 2:
The tracking system automatically calculates misregistration amounts and controls the movement mechanism without requiring manual intervention. The system self-adjusts the optical system alignment based on real-time image analysis, maintaining precision while reducing the operational complexity for users.
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
Enables high-precision tracking and imaging of the anterior segment by accurately calculating and compensating for eye movements, enhancing the accuracy of misregistration analysis and maintaining proper alignment and focus despite static features in the images.
Implementation Method 1
an optical system for acquiring data of a subject's eye optically
Implementation Method 2
a parallel movement amount calculator that performs a phase only correlation processing on the corresponding partial image and the partial image registered by the registration unit to calculate a parallel movement amount
Data Source
AI summary
An ophthalmologic apparatus includes an image sensor that acquires first and second images of an anterior segment of a subject's eye at different timings, and processing circuitry that calculates a rotational movement amount between a partial image in the second image and a corresponding partial image in the first image. The processing circuitry performs registration between the partial images in a rotation direction based on the rotational movement amount and performs a phase only correlation processing to calculate a parallel movement amount. The processing circuitry controls an actuator that moves the subject's eye and the optical system relative to each other based on at least one of the rotational movement amount and the parallel movement amount, specifies the partial image in the second image based on the first image and the second image, and calculates the rotational movement amount between the corresponding partial image and the specified partial image.